Control Tools

• Diagnostics availability

• Commercial diagnostic kits available worldwide

  Bacteriological diagnosis

  While basal media are available, antibiotic supplements for making the three top Brucella-selective media (Farrell’s, modified Thayer’s Martin and CITA) are commercially available only for Farrell’s and modified Thayer’s Martin media.

  Chemical reagents for the presumptive identification and typing of Brucella are available commercially, and sera and phages can be obtained from some OIE laboratories. However, these classical tests are being largely replaced by commercially available PCR kits for identification at genus or/and species level and for identifying OIE-recommended vaccines.

  Serological diagnosis

  Many commercial diagnostic kits are marketed. These include iELISA (humans and main domestic livestock species), cELISA (multispecies), FPA (multispecies), Brucellacapt (humans) and lateral flow immunochromatography (cattle, small ruminants and humans), which all detect antibodies to S-LPS components of Brucella. iELISA kits that use antigens derived from rough strains of Brucella are also commercially available for the diagnosis of B. ovis and B. canis. In addition, Rose Bengal, complement fixation and serum agglutination antigens (all valid for ruminants and humans) are available.

  Bacteriological diagnosis

  While basal media are available, antibiotic supplements for making the three top Brucella-selective media (Farrell’s, modified Thayer’s Martin and CITA) are commercially available only for Farrell’s and modified Thayer’s Martin media.

  Chemical reagents for the presumptive identification and typing of Brucella are available commercially, and sera and phages can be obtained from some OIE laboratories. However, these classical tests are being largely replaced by commercially available PCR kits for identification at genus or/and species level and for identifying OIE-recommended vaccines.

  Serological diagnosis

  Many commercial diagnostic kits are marketed. These include iELISA (humans and main domestic livestock species), cELISA (multispecies), FPA (multispecies), Brucellacapt (humans) and lateral flow immunochromatography (cattle, small ruminants and humans), which all detect antibodies to S-LPS components of Brucella. iELISA kits that use antigens derived from rough strains of Brucella are also commercially available for the diagnosis of B. ovis and B. canis. In addition, Rose Bengal, complement fixation and serum agglutination antigens (all valid for ruminants and humans) are available.

  GAPS :

  Bacteriological diagnosis

  Serological diagnosis

  Although available, costs of some tests (iELISA, cELISA, FPA, Brucellacapt) and ancillary equipment (iELISA, cELISA and FPA) are generally out of reach for many populations in Africa, Asia and Latin America.

  Rose Bengal Test reagent is inexpensive, and the resources required to run the test are also inexpensive and simple.

  Distribution costs and handing fees do make the RBT more expensive and more difficult to acquire for some locations, usually those that can least afford the additional charges.

  Almost all kits require cold storage. This may reduce availability in some resource-limited regions.

  DNA-detection methods

  There are commercially available kits for DNA extraction and amplification, but both suffer from validation problems.

• Diagnostic kits validated by International, European or National Standards

  Standardization (serological tests)

  WOAH and/or EU sera are available for standardization of most kits/tests for bovine, ovine (B. melitensis and B. ovis) goat (B. melitensis), pig (sera for B. abortus and B. melitensis can be used to standardise tests for B. suis) and dog (only an EU standard available for B. canis; canine brucellosis is not a WOAH listed disease) brucellosis, in some species for some specific tests (RBT/BPAT, CFT, SAT, iELISA, C-ELISA, FPA). Many commercial kits have been standardized using these sera.

  B. ovis positive and negative sheep sera are available and could be used to standardize tests (including iELISA) for the diagnosis of sheep infections by this rough Brucella species.

  GAPS :

  Existing standard sera are only appropriate for S-LPS or B. ovis hot-saline extract-based kits. If a protein-based kit (or other type of antigen) comes onto the market, then the existing standards may not be appropriate.

  While some of the standard sera were obtained with kits/tests previously validated with collections of sera representative of some specific epidemiological conditions, validation (i.e., the definition of the diagnostic specificity and sensitivity) with sera representative of the variable epidemiological conditions of many endemic countries is often pending.

  No serodiagnostic kits have been validated (or standardized with the specific host sera) for camelids, yacks, water buffaloes and other “exotic” species.

  Only few serological diagnostic tests have been validated for diagnosis of susceptible wild-life species.

• Diagnostic method(s) described by International, European or National standards

  Methodologically, CFT, iELISA, cELISA, FPA, RBT, CFT and the brucelline skin test for B. melitensis, B. abortus and B. suis infections of bovines, small ruminants and pigs are described in the 2023 WOAH Manual (update adopted in 2022).

  An independent chapter of this Manual describes the tests (CFT, AGID and iELISA) for diagnosing B. ovis infection of sheep.

  GAPS :

  Some of the methodological descriptions are open to some interpretations. Whilst this is advantageous in some respects, it can also lead to some drift in techniques between laboratories.

  The WOAH Manual no longer defines prescribed tests for international trade but provides general guidelines for each test depending upon the purpose. However, these are not broken down into host species. Instead, the Manual, advises that quantitative tests should be validated for its capability in each animal species and epidemiological situation. This may require local studies performed with existing well-standardized commercial kits.

• Commercial potential for diagnostic kits in Europe

  Very high since eradication-surveillance is compulsory in the EU in pigs and domestic ruminants and, moreover, brucellosis control is identified as a priority in many emerging economies, including most Latin American nations, China and India.For cattle and small ruminant brucellosis, the market for standard commercial kits that meet the usual requirements (i.e., as already available) is fairly full. Not the case for B. ovis/B. canis diagnostic tests.There may be an opportunity for niche kits to be developed to meet specific needs such as addressing false positive serological reactions caused by cross-reacting bacteria (FPSR) that arise from standard methods. Whereas FPSR are not a significant problem in ruminants, they represent a problem for international trade of pigs. It is uncertain if the niche market is big enough to support such tests if only used for secondary testing. The market for well-validated DNA amplification kits (including DNA extraction) able to identify the infecting species and vaccines in animal samples is high.

  GAPS :

  Immunological diagnosis

  No diagnostic kits have been validated (or standardized with the specific host sera) for camelids, yacks, water buffaloes and other “exotic” species. More information about test performance in these animals would be very useful.For new tests (LFiC and possibly others), despite their innovation a lack of sufficient validation may be more of a barrier to addition. Also, it may be difficult to precisely describe an approach to standardization. These issues do sometimes create a drag on the modernisation of the WOAH Manual.While some specific serological kits based on presented data might be a possible way for swine brucellosis to reduce FPSR rate, they have lower individual sensitivity than other tests. New serological kits based on accepted WOAH assays (ELISA, FPA) or on new methods could only be commercially successful if they have a much lower FPSR rate but the same sensitivity as existing certified kits.Possibly some space in the market for niche assays based on non-OPS antigens (i.e., native hapten polysaccharide and protein antigens for the brucelline skin test).Potentially good for DTH skin tests (brucelline or equivalent S-LPS-free protein extracts) discriminate FPSR by cross-reacting bacteria with sensitivity that make them useful at herd level but no antigens for this purpose are commercially available.

  DNA-detection methods

  Very good for kits that would be proved effective in direct diagnosis of animal and human samples. Despite molecular (e.g. PCR) detection having very high analytical sensitivity, the insufficient presence of analyte in readily accessible samples such as blood, serum and even milk so far renders current methods insufficient for use as a confirmatory test.

• DIVA tests required and/or available

  In countries that need vaccination, and provided they have the essential infrastructure (animal census and tagging, repeated access to the animals, appropriate laboratories and budget), a suitable and effective DIVA test could be of help in completing eradication once a vaccination plus test and slaughter programme can be implemented. Its absence may prevent eradication programmes from initiation due to the anticipated difficulties that will ensure.Several competitive and blocking ELISAs are commercially available, and some claim to enable differentiation of vaccination from infection in combination with certain vaccines. However, this is not true and there is also information to indicate that such assays lack sensitivity.

  GAPS :

  Replacing current S-LPS or O-PS tests with others of equivalent diagnostic sensitivity and specificity compatible with S19, Rev1 or new S vaccines seems exceedingly difficult. The issue of a DIVA test for infection by S Brucella species is likely to require research on alternative vaccines against cattle and small ruminant brucellosis.

  An effective DIVA vaccine and diagnostic partnership could encourage more eradication programmes to take place.

  A DIVA test for the diagnosis of B. ovis infection of sheep may be necessary if a B. ovis specific vaccine is developed.

• Vaccines availability

• Commercial vaccines availability (globally)

  Live attenuated vaccines S19, Rev 1 and RB51 and are the only vaccines recognised for use by the WOAH. S19 and Rev 1 vaccines can be produced without commercial infringement but should be extensively tested for efficacy and safety by recognised protocols before use.Rev 1 and S19 for conjunctival route are available from several makers and marketed internationally.Whereas Rev 1 and RB51 are widely available, marketing of S19 has been discontinued in some countries.

  GAPS :

  There are no B. ovis-specific and pig brucellosis vaccines.

• Marker vaccines available worldwide

  RB51 is an R vaccine (thus negatively marked) commercialized over twenty years ago. It triggers antibodies detected in iELISA,FPA and lateral flow immunochromatography (LFiC) but not in RBT.

  GAPS :

  Positively marked vaccinesAny immunological marker introduced in an S vaccine (current S19 and Rev1 or any future efficacious/safe S vaccine) would require (1) an associated DIVA tests as sensitive as S-LPS tests and (2) to trigger a response outlasting the anti-S-LPS antibody response. Rev 1 vaccine and S19 have been antigenically labelled with GFP, or carrying a modified O-PS (acetylated perosamine) but they do not fulfil (1) or (2). In addition, the candidate carrying the modified O-PS does not protect Negatively marked vaccines.These include (a) R live vaccines such as RB51 and a R vaccine deleted in pgm (being commercialized in Venezuela and possibly in other Latin American countries but triggers anti O-PS antibodes detected in all tests and its efficacy and safety have not been proved properly); (b) BP26 deleted Rev1 or S19 and (c) new subcellular vaccines lacking the O-PS epitopesThese vaccines do not solve the DIVA uncertainty generated by anti-S-LPS response triggered by contacts with wild-type brucellae in the situations where vaccination is necessary.No R vaccine investigated matches the WOAH recommended S vaccines in protection.The DIVA test associated with Rev 1 and S19 deleted in BP26 is not sensitive enough.Despite claims, no subcellular vaccine has been demonstrated to be effective, including a recent viral influenza vector vaccine carrying Brucella proteins L7/L12 and Omp16 (apparently registered in Kazakhstan). This approach requires research on cellular immunity to intracellular parasites and new adjuvants.

• Effectiveness of vaccines / Main shortcomings of current vaccines

  The WOAH endorses two cattle vaccines (B. abortus S19 and RB51) and a small ruminant vaccine (B. melitensis Rev 1). All are live attenuated vaccines.Only S19 and Rev 1 have been proved to be effective in brucellosis control and eradication.S19 has been instrumental in the control and eradication of brucellosis in the USA, Australia, the UK and several EU countries. While some have reported success in eradication programs based on RB51 test and slaughter, others have presented data showing that RB51 does not contribute significantly to test and slaughter.

  GAPS :

  Abortions when applied to pregnant animalsThese three vaccines are abortifacient in pregnant animals (a problem in the mass vaccination programs currently necessary in large areas of the world). For S19, the problem is minimised by conjunctival instillation. The abortifacient effect is a major problem of Rev1 and a largely ignored problem of RB51 (although such use would be off label).

  Interference in S-LPS diagnostic testsA problem of S19 and Rev 1 that can be minimised by conjunctival administration in young animals.A problem of RB51 in iELISA, cELISA, FPA and LFiC (but to a lesser extent than subcutaneous vaccination with Rev1 and S19) but not RBT.

  ProtectionA single dose of S19 or Rev 1 provides useful life immunity against both B. abortus and B. melitensis.RB51 protection against B. melitensis unknown. Against B. abortus inferior to that provided by S19 and waning in less than 4 years. Usefulness of re-vaccination unknown.Protection by any of these vaccines can be overcome by large doses of virulent bacteria.

• Commercial potential for vaccines in Europe

  In most EU countries B. abortus has been eradicated and no vaccines are required. However, the S19 for conjunctival use (associated or not with potential DIVA tests) could be of help and interest in completing B. abortus eradication in P, IT, and GR, since some regions in these countries still need adequate vaccination programs.In countries where B. abortus is still endemic there is a case that there is commercial potential for a new vaccine, especially if it is safer than existing vaccines and has DIVA properties. The commercial potential for new B. melitensis vaccines is smaller due to the lower value of the small ruminant host and the market pull is lower.New vaccines associated or not with DIVA tests could be important for eradicating B. melitensis, since most infected countries (P, IT, GR,) need vaccination.New vaccines (and perhaps associated DIVA tests) should be of interest also in the case of B. ovis infection, an increasing problem in regions in which B. melitensis has been eradicated and Rev 1 vaccine forbidden.Vaccines against B. suis are not required for industrial indoor breeding systems, but could be of interest in outdoor (several EU countries) or extensive breeding systems (at least in P and ES).

  GAPS :

  Currently, the main obstacles for the commercialization of brucellosis vaccines are:

  • the existence of endemic countries that are not open markets (for example, China)
  • lack budget and infrastructure to implement brucellosis control
  • lack of vaccine product that possesses protective efficacy of S19 and Rev1 but without the negative attributes

• Regulatory and/or policy challenges to approval

  Unclear depending on the country/market.

  GAPS :

  Some large endemic countries (China, Russia, possibly others) are not open markets and favour their own non-WOAH recommended vaccines, of which there is a large variety not properly investigated for efficacy and safety (B. abortus 104-M, B. abortus 82 or SR82, B. abortus 75/79-AB, B. abortus KB 17/10, B. abortus A19, B. melitensis M5, B. melitensis M5-90, and B. suis S2).Many countries have no effective regulatory/policy rules (at least most Sub-Saharan African countries).

• Commercial feasibility (e.g manufacturing)

  For attenuated live vaccines, technology & experience gained in Rev 1 and S19 production in the EU.

  After the production of the Master Seed Lot by the manufacturer a thorough control in vitro and in vivo of this pivotal biological starting material must be performed by a Reference Laboratory according to WOAH guidelines.

  After satisfactory control, the Master Seed Lot can be used by the manufacturer for the production of Brucella vaccines. However, some basic processes must be respected.

  1. The seedlot system must be respected in order to have a robust and validated technology to avoid qualitative difference from batch to batch.
  2. These vaccines have to be produced in Category 3 confined area with adequate equipment as fermentor, centrifuge and negative pressure freeze-drier.
  3. Beside the technology of production, rigour in process and batch release controls must be applied. This last test should be performed internally by the manufacturer and externally by Reference Laboratory.

  GAPS :

  A novel vaccine that did not require the additional biohazard controls in place for Brucella vaccine production would be desirable. S19, RB561 and Rev1 are live stains that are infectious for humans. Rev1 additionally carries antibiotic resistance to streptomycin an important treatment option.

• Opportunity for barrier protection

  N.A.

• Pharmaceutical availability

• Current therapy (curative and preventive)

  Treatment is only necessary in humans (exceptionally in genetically valuable animals or endangered breeds).Several effective regimes encompassing the different forms of the human disease are available.

  GAPS :

  Streptomycin shortage in numerous areas of the world may hamper the implementation of the doxycycline-streptomycin regimen (see 16.6.).For specific problems caused by antibiotic resistance in vaccines.

• Future therapy

  None known by the group. Linked to the development of new antibiotics with good intracellular penetration or breakthrough in alternative therapeutic tools (such as bacteriophages)

  Care needs to be taken with any antibiotic treatment of animals not to induce antimicrobial resistance either in Brucella (which does not readily adopt AMR) or other bacteria present in the host.

• Commercial potential for pharmaceuticals in Europe

  Potentially high because of the likely high worldwide incidence. Potential market in India where in many circumstances cattle cannot be slaughtered due to religious beliefs. Also, a possible market for canine brucellosis (treatments for companion animals command higher prices than those for livestock).

  GAPS :

  In endemic resource-poor countries, access to treatment/compliance is limited.

• Regulatory and/or policy challenges to approval

  Beyond the competence of the working group.

• Commercial feasibility (e.g manufacturing)

  Beyond the competence of the working group but quite likely to be too expensive in many cases.

• New developments for diagnostic tests

• Requirements for diagnostics development

  New tests (serological or molecular) need validation (optimization for diagnostic sensitivity and specificity).Good opportunities for molecular tests (PCR) provided they are diagnostically sufficient well-standardized and validated. DNA extraction protocols are also an important part of the molecular diagnosis process.For most endemic countries, new tests should not require expensive infrastructure and ancillary equipment.

• Time to develop new or improved diagnostics

  Variable depending upon the animal species and resources. Being able to conduct effective validation is often a significant barrier. Variable depending upon the animal species and resources. Being able to conduct effective validation is often a significant barrier.

  GAPS :

  Optimally, for wild-life tests gold standard serum collections should be based on bacteriological studies and these may be difficult to carry out.

• Cost of developing new or improved diagnostics and their validation

  Difficult to estimate.

• Research requirements for new or improved diagnostics

  New tests (specially PCR, RT-PCR) are usually defined for analytical sensitivity and specificity, which is largely insufficient. They should be validated in different animal samples (milk, vaginal exudates, tissues upon necropsy, etc) (brucellosis-free populations for specificity, vaccinated animals, infected animals proved by correct bacteriological testing and correct serological tools). A better understanding of the interaction between antigen and antibody may yield diagnostic improvements.

  GAPS :

  No PCR has been appropriately validated and met the threshold for effective use in diagnosis in animals from clinical samples.

• Technology to determine virus freedom in animals

  Immunoenzymatic tests such as iELISAs could be adapted.

• New developments for vaccines

• Requirements for vaccines development / main characteristics for improved vaccines

  According to WHO (1999), in animals of both sexes and of any age, a perfect brucellosis vaccine should: i) be harmless (i.e., safe: no abortions, no excretion) and prevent infection with a single dose, ii) not stimulate antibodies interfering with serodiagnosis, iii) not be transmitted to humans or other animals (which includes no contamination of meat, edible organs, milk and dairy products), iv) be stable in vitro and in vivo, v) be readily cultivable under large-scale fermentation conditions, and vii) carry markers for an easy differentiation from field isolates. Another requisite not listed by WHO 1999 is vi) affordable.For the WOAH-recommended vaccines S19 (cattle) and Rev1 (small ruminants), conjunctival instillation minimizes problems concerning requirement ii). Conjunctival formulations for S19 and Rev1 are commercially available.

  Despite being a WOAH vaccine, RB51 is not DIVA in any test in infected environments and does not confer suitable protection. It lacks safety in animals and can cause difficult to diagnose infection in humans.

  Despite being a WOAH vaccine, RB51 vaccinated animals may seroconvert to become positive to RBT with sufficient infection pressure from smooth Brucella strains. Sufficient protective efficacy is disputed, and, like other Brucella vaccines, it presents safety hazards to target hosts and humans. Human infections are particularly troubling due to difficulties in serodiagnosis and the induced resistance to a key antibiotic used for treatment (especially during pregnancy).

  GAPS :

  The current failure of Russian and Chinese vaccines to control brucellosis in these countries may bring an opportunity for WOAH-approved or new vaccines

  There is no clear need for a new cattle vaccine. B. abortus S19 was instrumental in control/eradication in the USA, Canada, most EU countries, the UK and Australia. Although S19 does not perfectly fulfil i), ii) and iii), these problems are comparatively reduced by conjunctival administration in females, even in mass vaccination campaigns, and ii) is irrelevant in mass vaccination campaigns.Although evidence is scarce, subcutaneously administered S19 is considered unsafe in males. The safety of conjunctival administration of S19 in bulls should be investigated.Studies in camelids, yacks and water-buffaloes would be necessary to investigate the safety and efficacy of S19/Rev 1 in these animals.There is a clear need for a new vaccine against B. melitensis infection of small ruminants that solves the serious safety issues of Rev1. Although effective in control/eradication in several EU countries, it is abortifacient and excreted in milk (adult vaccination), virulent for humans and streptomycin-resistant), and cannot be recommended for mass-vaccination or vaccination in areas where no well differentiated lambing/kidding seasons exist. New small ruminant vaccines that solve this problem are being investigated under the GalvMed competition but number, type, progress and company commitments are mostly confidential.There is no commercial B. ovis specific vaccine, even though some subcellular and live R vaccines have proved effective in controlled experiments. Such a vaccine may be necessary in countries-regions in which B. melitensis has been eradicated (EU, Australia, New Zealand and possibly others) and Rev 1 vaccine is banned.There is no B. suis vaccine for pigs. Such a vaccine may be necessary in areas where domestic pigs are bred outdoors or extensively in contact with wild boars.

• Time to develop new or improved vaccines

  From concept to industrialisation and to EU marketing authorisation, it will take 10 years or longer depending on whether improvement or development of completely new vaccines is considered.To develop a new vaccine (tagged, sub-unit, live modified) may take longer than the improvement of the existing Rev 1 and S19 vaccines. However, since the Master Seed Batch would also be different, the registration of S19 or Rev1 “improved” derivatives will have to go through all the development steps as for a new vaccine, including a registration of a new dossier with new parts 2 (analytical), 3 (safety) and 4 (efficacy).Main steps for development of new vaccines:

  1. Building project with relevant tasks.
  2. Labscale in vitro & in vivo research.
  3. Controlled experiments in target hosts (and validation in parallel of Master Seed Batch / Working Seed Batch). Two phases:(a) study of safety in females at mid-gestation and males.(b) protective efficacy (challenge) trials in target animals.
  4. Research to set the Minimal Protective Dose; production of the Pilot Batches.
  5. Registration: more attention if the vaccine is considered as Genetically Modified Organism.
  6. Industrialisation of the technology, field trials.

  GAPS :

  Main obstacles:

  • Human resources and budget.
  • Few teams remain that have the necessary know-how on evaluation of brucellosis vaccines (steps 3 and 4).
  • Availability of category 3 facilities. Particularly challenging due to the size of the primary hosts and the duration of the experiments.
  • Genetically Modified Organism legislation in Europe.
  • Decisions concerning project management and adequate repartition of tasks between Public Institutions/Laboratories and Industry.
  • Steps 3, 4 should be very challenging in animals other than cattle and small ruminants.

• Cost of developing new or improved vaccines and their validation

  Difficult to estimate but very high. A factor which dramatically increases costs is the requirement of category 3 facilities (Laboratory, Industrial and challenge on target animals).

  Cost will also increase if DIVA associated tests are also to be developed.

• Research requirements for new or improved vaccines

  Category 3 facilities.

• New developments for pharmaceuticals

• Requirements for pharmaceuticals development

  Current treatments involve administering two (three in some clinical forms) antibiotics for up to 6 weeks, which makes compliance difficult in many endemic areas of resource-limited countries. There is a low rate of relapses and therapeutic failures.

  GAPS :

  Any new therapy that could be 100% effective in shorter / simpler/ cheaper regimes and totally avoid parenteral administration would be worth investigating.

• Time to develop new or improved pharmaceuticals

  Beyond the competence of the working group.

• Cost of developing new or improved pharmaceuticals and their validation

  Beyond the competence of the working group.

• Research requirements for new or improved pharmaceuticals

  Strictly, double-blind studies.A correct diagnosis and a complete clinical definition of cases in the study, including:

  (a) epidemiological data;

  (b) probable infecting species;

  (c) estimated time of evolution before diagnosis;

  (d) identification of complications.

  Inclusion of cases of pregnant women and children.

  Strict compliance during the study.

  Prolonged follow-up.

  GAPS :

  Confusion created by recent reports that do not fulfil the requirements listed here.

Disease details

• Description and characteristics

• Pathogen

  The genus Brucella includes the “classical” species recognized long: B. melitensis, B. abortus, B. suis, B. neotomae, B. canis and B. ovis. B. melitensis B. suis, and B. abortus were divided long go into biovars. In addition, isolates from marine mammals have been grouped into two species: B. pinnipedialis and B. ceti; strains isolated from the common vole are proposed to belong to a new species: B. microti. Whereas B. melitensis, B. abortus, B. canis and B. ovis have well defined characteristics, B. suis shows a great internal diversity and biovar 5 overlaps with the B. microti strains. Few isolates of B. neotomae have been studied, and the studies of the strains from marine mammals need to be complemented with additional strains from the Pacific Ocean. More recently B. papionis (baboon isolate) has been discovered and described. From a phylogenomic standpoint the above-mentioned species are relatively homogenous and form a “core” group. Brucella strains, often described as “atypical”, have been described more recently and these are clearly distinct from the core group. However they are part of the distinct Brucella clade and far more distantly related to Ochrobactrum. These atypical strains include include B. inopinata (human isolates), B. vulpis (from foxes), and several isolates from amphibians. On the other hand, B. nosferati (recently reported to infect vampires in Central America) and two Brucella strains isolated from two human cases in Guiana group line with the “core” brucellae. There are a few isolates different from the above-listed brucellae that remain to be thoroughly characterized.All species investigated behave as facultative intracellular parasites. For pathogenicity mechanisms of those species investigated in more detail (mostly B. abortus and B. melitensis and to less extent some B. suis biovars).

  GAPS :

  The taxonomy of the Brucella genus needs permanent attention because of the probable isolation of hitherto unknown brucellae and the confusion created by the proposal to include Ochrobactrum in the genus.

  For epidemiology studies, molecular analyses should be routinely included since there is clear evidence that classical biovar typing lacks resolution (B. suis case) and isolates from geographical areas other than Europe, the near East and N. and S. America do not necessarily fall within the previously described biovars.

  In vitro and in vivo laboratory studies to understand the virulence/pathogenicity/host range/zoonotic potential of “new” and “atypical” brucellae.

  Better understanding of the basis of the pathogen host range.

• Variability of the disease

  The severity of brucellosis varies according to the host and the infective species. Although the incidence is not well-known, brucellosis is a world-wide distributed disease of livestock and humans. Brucella has been isolated from variety of terrestrial wildlife, including several amphibians, bats, and marine mammals worldwide.The brucellae are highly clonal and stable in the hosts. However, two types can be distinguished naturally: rough (R) and smooth (S). R brucellae (B. canis and B. ovis) show a narrower host range (sheep and dogs) than the remaining Brucella species that all are S. The molecules responsible for these phenotypes are the cell envelope lipopolysaccharides. In S species, these molecules carry an O-polysaccharide not present in the R species. B. abortus preferentially infects cattle (and water buffalo); B. melitensis, sheep and goats (but B. melitensis infections of cattle are not unusual in mixed breeding systems); B. ovis, sheep and B. canis dogs. B. suis can be mainly isolated from swine (including wild swine), reindeer, hares, wild rodents and some other wildlife species. Marine mammals harbour B. pinnipedialis and B. ceti. B. microti from common voles has been proposed as a new emerging pathogen, but clusters genetically with B. suis biovar 5. B. abortus, B. melitensis and some B. suis biovars can infect animals other than their primary hosts, including wildlife, depending upon the epidemiological circumstances.

  GAPS :

  Epidemiology supported by molecular analyses with attention to changes in host-range “new” brucellae, the (potential) role of wildlife animals as reservoirs and the possible zoonotic characteristics of new brucellae.

• Stability of the agent/pathogen in the environment

  Classical brucellae do not multiply outside the hosts but may persist in the environment, mostly associated to animal products. Adverse environmental factors are high temperature, acid pH, dryness and exposure to sunlight. In temperate climates, particularly in winter, B. abortus may survive for several months in abortions, placenta and tissues; in exudates and abortion discharges for less than a month; in liquid manure in fresh conditions for at least 8 months; in dairy products (milk, butter, cheese, cream and ice cream), and depending upon pH and refrigeration, from one week to 4-5 months. In refrigerated organs, for at least 2 months; in water for up to 2 months. The data available suggest similar persistence for B. melitensis or B. suis.While B. microti has been isolated from the proximity of vole burrows, there is no evidence that it multiplies in soil.B. pinnipedialis and B. ceti survive in artificial sea water at 4ºC (time not reported) but viability decreases significantly at 10ºC.

  GAPS :

  Information incomplete concerning non-pasteurized dairy products, particularly those obtained by traditional procedures (souring, etc.).

  Viability/permanence of “new”&”atypical” brucellae in the environment.

• Species involved

• Animal infected/carrier/disease

  The brucellae infect a wide range of animals, especially the smooth strains, and the known range is getting wider all the time as the organism is looked for in more possible host species.Cattle, yaks, water buffaloes, sheep, goats, reindeer, camelids, swine, horses, reindeer, hares, seals (pinnipeds), dolphins and porpoises (and other toothed whales), and dogs are susceptible. Poultry may be artificially infected but the disease is of no importance. But for hares and wild boars, these seem to be of little practical importance as reservoirs in Northern Europe, USA, Canada and Mediterranean countries.Any animal that has the disease poses a potential risk of spread to others.Some animals (ruminants) are known to be latently infected where the organism is present but at sub-clinical and sub-detectable levels. Whereas abortion is a common result of first pregnancies, this is not so in the second, third, etc. Calves born to these infected mothers can acquire brucellosis without showing any symptom of the disease or being positive in diagnostic tests, but they usually abort during the first pregnancy and transmit the disease, thus acting as latent carriers. There is much circumstantial evidence that latent infections are a source of re-introduction of brucellosis in flocks.

  GAPS :

  A better understanding of latency and of detecting latently infected animals is important. The inability to screen out such animals during movement tests presents a risk to the disease-free status of target destinations.

• Human infected/disease

  Human infection comes from direct or indirect contact with animals and animal products B. melitensis, B. suis biovars 1,3 and 4, and B. abortus cause human brucellosis. Indirect and fragmentary data show that B. melitensis and B. suis are more infectious and cause a more severe disease than B. abortus. Nevertheless, B. suis biovar 2 is not highly virulent in humans. B. canis is considerably less virulent but, since contact of dogs with humans is frequent, poses a potential risk, especially against the background of many imported dogs from endemic areas into the EU or UK. A few cases also show the virulence of B. neotomae, the marine mammal strains and “new”&”atypical” brucellae for humans. No infections by B. ovis have been reported.Vaccines B. melitensis Rev1, B. abortus S19, and B. abortus RB51 are infectious for humans, and the clinical picture is similar to that caused by their wild-type counterparts. However, regimes to treat Rev1 or RB51 infections should not include streptomycin or rifampicin, respectively.

  GAPS :

  Data on the virulence for humans of brucellae other than B. melitensis, B. abortus, B. suis biovars 1-4 and B. canis are scarce or do not exist.

  Currently used serological tests for the diagnosis of human brucellosis do not detect infections by RB51.

  Some atypical brucellae have an O-PS structurally and antigenically different from the N-formyl-perosamine homopolymers in core brucellae and are possibly infections would not be picked up by the existing S-LPS diagnostic tests.

• Vector cyclical/non-cyclical

  There are no true vectors. Conjunctival transmission by Musca domestica, Tabanus, spp., and Stomoxys calcitrans has been experimentally shown in cows, goats and sows but is considered to be irrelevant.Blood-sucking insects and ticks that have fed on experimentally infected laboratory animals can harbour brucellae for a few days. There are reports on transovarial transmission in ticks under these experimental conditions.

  Brucella bacteria have been isolated from several ticks (Dermacentor, Hyalomma, Rhipicephalus spp). In addition, Brucella DNA has been amplified or shown by next generation sequencing in species of Boophilus Dermacentor, Hyalomma, Rhipicephalus and Ixodes. However, there is no evidence for any role of these arthropods in transmitting the disease under natural conditions.

• Reservoir (animal, environment)

  Domestic livestock. The animal disease is endemic in many areas and this makes the establishment of free areas very difficult as all surrounding areas may still have infections. History is filled with prevalence reduction and disease eradication programmes which succeed in the short term but fail in the long term due to reintroduction of the disease from neighbouring infected areas or importation by animal trade. In such cases prevalence may rapidly reach or exceed previous levels.

  Wildlife. The presence of the disease in wildlife is a potential reservoir of infection. However with only two exceptions (Yellowstone Park and French Alps, both due to anthropogenic effects) the infections in wildlife lack of epidemiological significance for domestic ruminants. In Europe, the wild boar and hare populations contain B. suis biovar 2 infected animals and are a source of brucellosis for pigs bred extensively or outdoors. However, this biovar poses very little risk for humans. In other areas, feral pigs infected with B. suis biovar 1 and 3 are source of human infections. But for marine mammals, wild boar, hares and some wild rodents, brucellosis in most forms of wildlife seems to be a spill-over disease originated through contacts with domestic livestock. In some areas of the US, bison (Bison bison) and elk (Cervus canadensis) are infected by B. abortus as a result of contacts with cattle and, after eradication of brucellosis in the latter, act as a potential reservoir.

  GAPS :

  Greater understanding of the role of wildlife and hosts of “new” brucellae.

• Description of infection & disease in natural hosts

• Transmissibility

  Brucellosis by S brucellae is highly transmissible, and spreads very rapidly in immunologically naïve herds and flocks. The main routes of transmission of classical species in domestic livestock are well known. Infected ruminants and swine may shed brucellae via urine, but the aborted foetus, foetal membranes and fluids, genital discharges and milk are the most important sources of contagion. Milk transmission becomes very significant when hygienic measures are not taken during hand milking or thorough disinfection of milking equipment between animals. Semen produced during the acute early stages of infection is also a source of contagion, and artificial insemination spreads the disease more readily than natural insemination. Congenital/perinatal transmission also occurs.The disease is usually transmitted in humans and animals by ingestion of infective organisms, usually by consumption of raw milk or unpasteurized dairy products. However, infection via the ocular mucus membranes may occur and infection may take place via inhalation due to aerosols. Congenital/perinatal transmission has also been reported.

  GAPS :

  Transmission of brucellosis in marine mammals is largely unknown.

  Attention should be given to potential transmission routes by non-classical brucellae.

  Although the mechanisms for intra herd transmission is clear the relative potency of each pathway is not. To what extent can milk spread disease through a herd when abortion/parturition material has not been in contact?

• Pathogenic life cycle stages

  None.

• Signs/Morbidity

  Brucellosis lacks pathognomonic symptoms/signs in, at least, domestic livestock and humans.In domestic livestock, abortion, birth of weak offspring, infertility and genital lesions in males are the most common but not specific manifestations of brucellosis, and are not constantly present. Encephalitis is relatively frequent in infected marine mammals.

  GAPS :

  Attention should be given to potential infections by non-classical brucellae.

• Incubation period

  It seems to vary considerably (from weeks to months) depending upon several not easy to precise or well-known factors, including the strain, the infective dose and route (ingestion, inhalation, contact) in each host species and individual susceptibility. In cattle and small ruminants, these factors also include age, immunologically status (previous exposures and vaccination), challenge size (conversely related) and physiological status, particularly the state of pregnancy (shorter incubations times as infection happens closer to mid pregnancy).

• Mortality

  After infection with B. abortus/B. melitensis/B. suis there is low mortality of infected animals; however, there is a very high mortality of unborn foetuses especially during the first pregnancy when the animal has the disease. Thus, the rate of abortions varies between 0 to 40% in cattle, sheep, goats and swine, depending upon whether the disease has been recently introduced in a flock or the flock is chronically infected. Perinatal mortality is estimated between 0-20%. Adult mortality seems low or very low, although exact figures are difficult to find. In cattle, 1% of cows with abortions may die due to metritis and other secondary complications. (In countries with a test and slaughter control program mortality may be considered high as all animals identified as infected are slaughtered and ‘at risk’ or ‘contact’ animals are also frequently culled.).

• Shedding kinetic patterns

  In cattle, small ruminants and swine shedding through vaginal fluids is very intense after abortion / parturition and wanes in several weeks in most cases. However, excretion in milk in these species is very frequent and may last for several years. A significant proportion of infected males may excrete brucellae in semen for several months/years.The main period of shedding of infective organisms is at birth or abortion when the material exuded is highly infections containing many infective doses. Although this appears to be intermittent, a significant number of animals shed Brucella in their milk and may be responsible for most of an infected herds overall shedding via this route.

  GAPS :

  The shedding of Brucella in milk appears to be transient and variable between individuals but the reasons for this are not well understood.

• Mechanism of pathogenicity

  The brucellae are facultative intracellular parasites. Their cell envelopes carry molecules with reduced pathogen-associated molecular patterns (chiefly free-lipids and lipid A-core) that reduce early detection by innate immunity. This opens a time window to reach the intracellular niche (an endoplasmic reticulum-derived vacuole) before adaptive immunity is activated. Several virulence factors, including a type IV secretion system and genetic regulators are known to be involved in reaching the intracellular niche. The brucellae also block apoptosis and thus reproduce in massive numbers in several types of cells (dendritic, macrophages, epithelial, trophoblasts, etc.).After penetrating the mucosa, the organism localizes in the lymph nodes nearest to the portal of entry and then spreads to other lymphoid tissues and organs. Bacteraemia develops at the beginning, and becomes intermittently later, often recurring at abortion/parturition. In the pregnant animal the uterus is invaded by way of the endometrium and uterine glands; then the infection spreads into placental cotyledons. Invasion of the allanto chorion leads to infection of foetal blood vessels, placental fluids and foetus itself. Erythritol and/or partial immunosuppression/tolerance in placenta may be factors accounting for this particular tropism. Abortion is the outcome, with abundant bacterial shedding and spreading of the infection to supramammary lymph nodes (and others) and milk.

  GAPS :

  A better understanding of the mechanisms of pathogenicity could help to design better vaccines. These studies could include (at least):

  • The role of most VirB effectors in different types of cells, role of master regulators, metabolic adaptations, implications of asymmetrical cell division, etc. and the interaction with host immunity during the stages of the disease in natural hosts.
  • Comparative studies of virulence factors across all brucellae (including “new” species) to improve our understanding of the adaptation to intracellular life and pathogenicity of these bacteria
  • In vitro and in vivo laboratory studies to understand the virulence/pathogenicity/host range/zoonotic potential of “new” brucellae.
  • The pathology of the agent within each natural host other than humans, ruminants or swine (camelids, yaks, water buffaloes, etc.), and the underlying mechanisms for host preference/specificity.

• Zoonotic potential

• Reported incidence in humans

  The incidence is insignificant in the USA, Canada, Australia, New Zealand and Japan. In the EU, 198 cases (38 acquired outside the EU) in 2022.In other areas, the disease is largely underreported and underdiagnosed and the actual number of human cases is not known. However, the incidence is thought to be high (2,100,000 cases /year, or 340,000-19,500,000 cases/year according to two relatively recent estimates; the often quoted 500,000 new cases/year worldwide figure has no support).According to partial reports, exceedingly high and increasing in Mongolia and Northern Mongolia province of China.Under-reporting is associated to scarcity of medical services and lack of a keen awareness of the possible disease. Also, under-diagnosis and misdiagnosis exist because of misunderstandings on the value/interpretation of the tests and imperfect kits.

  GAPS :

  Critically important gap (human brucellosis is a main driver for implementing hygienic measures, control and eradication).Medical/healthcare infrastructure.

  Disregard/ignorance of existing knowledge on diagnostic tools for human brucellosis.

  What is the infectious dose for humans via inhalation or consumption for each species of Brucella, and what is variation within species (is there much variation within species).

• Risk of occurence in humans, populations at risk, specific risk factors

  It can be high depending on the prevalence of the animal disease and implementation of pasteurization of milk and dairy products.The populations at greatest risk are those that regularly come into contact with infected animals and those that consume unpasteurised dairy products. Such populations therefore include farm workers, especially subsistence farmers, veterinarians and slaughterhouse workers and consumers of many resource-poor countries where milk and traditional dairy products are sold unpasteurized in informal markets.Laboratory workers in endemic countries are also at risk. This risk extends to human clinical laboratories in brucellosis-free countries because of lack of awareness of a potential Brucella infection in travellers or immigrants coming from endemic countries.

• Symptoms described in humans

  Symptoms vary with the Brucella species and the population involved. The incubation period can be from few days to up to a year but two weeks is probably common. In general terms, B. melitensis causes more severe disease, followed by B. suis and then B. abortus. Acute forms are diagnosed more often in urban settings because of the usually easier access to healthcare; long evolution cases with complications occur more often in rural settings. Patients with acute brucellosis may manifest a wide spectrum of symptoms including fever (undulant or not), sweats, malaise, anorexia, headache, arthralgias, myalgias, backache and weight loss. Lymphadenopathy, splenomegaly and hepatomegaly are found in some cases. Complications can occur anywhere in the body. They include spondylitis, sacroileitis, osteomyelitis, meningitis, orchitis and abscesses. The morbidity is significant and mortality rate is low (2% - 5% in untreated cases, usually caused by brucellar endocarditis). Increased rates of spontaneous abortion, premature delivery and intrauterine infection with foetal death have been described, but it is unclear whether these occur at rates higher than in other bacterial diseases.

• Likelihood of spread in humans

  Not significant under normal circumstances. Human to human transmission has been rarely associated with blood transfusion, bone marrow transplantation, transplacental or perinatal exposure, sexual intercourse and breast feeding. However, there is limited data for all these claims. This lack of data shows that these routes of transmission are not significant compared to those from animals to humans.

• Impact on animal welfare and biodiversity

• Both disease and prevention/control measures related

  Animal movement tracking, husbandry and sanitary practices and vaccination policies help to prevent and control spread.Rare breeds of domesticated animals are threatened, often not by the disease directly but by slaughter prescribed by surveillance and eradication schemes. At least in EU countries, several bovine, ovine, caprine and porcine endangered local breeds can be seriously affected by the disease since stamping out measures have to be implemented compulsorily for eradication.

  GAPS :

  Legislation/rules for eradication should be modified (at least in the EU) in the case of endangered species or breeds and control methods (vaccination) different from depopulation considered.

• Endangered wild species affected or not (estimation for Europe / worldwide)

  None known (at least in the EU) but possible. Many species can be infected including sea mammals. The disease may affect the fecundity of many wildlife species.

  GAPS :

  The prevalence and effect of the disease in wildlife.

• Slaughter necessity according to EU rules or other regions

  Domestic livestock. Currently, brucellosis is a list B disease (cattle, ruminants and swine); so, compulsory eradication policies are required in EU member states. This will involve slaughter at some stage. It is necessary/highly recommended (a), in the last steps of eradication when test and slaughter programmes are implemented; (b) in outbreaks in free areas (however, vaccination [generally forbidden in the EU] could be effective and the best alternative in the case of endangered breeds).

  Wildlife. There is a high necessity for slaughter if the wildlife presents a significant threat of infection to valuable livestock.

  GAPS :

  Environmental problems with destruction of slaughtered animals (EU).

• Geographical distribution and spread

• Current occurence/distribution

  Global occurrence. Less than 30 countries are free of brucellosis in livestock (including 21 EU countries free of B. abortus and 20 free of B. melitensis [year 2022]), but many of these countries maintain a wildlife reservoir. EFSA records provide useful data for EU countries.Although indirect evidence (abattoir studies and human cases) shows endemicity in many countries, the prevalence is not known (lack of animal censuses, no or flawed seroprevalence studies, flawed meta-analysis and scooped reviews).Intensification of animal breeding in very large dairy farms has led to a high increase/emergence of cattle brucellosis in some countries (China).Apparently not currently controlled in countries of the former USSR.

  GAPS :

  No reliable data for parts of the Near East, Asia, Africa and Latin America.The prevalence and effect of the disease in wildlife.

• Epizootic/endemic- if epidemic frequency of outbreaks

  Brucellosis is endemic in many areas of the world. In many such areas new outbreaks or re-emergence occur frequently. Epizootic outbreaks occur when infection first enters an immunologically naïve flock/area, or several years after eradication.

• Speed of spatial spread during an outbreak

  The speed of spread is strongly linked to the movement of infected animals and can occur rapidly when there are no physical barriers between breeding animals or herds.

  Spread is mainly related to contact with reproductive material rather than direct animal to animal contact & is therefore slower to spread that diseases where direct contact can spread infection, unless abortion and release of infected fluids occurs soon after move.

  The disease can also be spread through transported fomites that come into contact with infected animals. It is usually high in immunologically naïve flock/ area.

• Transboundary potential of the disease

  The disease is widely spread and is already very ‘transboundary’. New outbreaks may readily spread across boundaries when there is unrestricted movement of animals across them. Higher where extensive breeding is used.

• Route of Transmission

• Usual mode of transmission (introduction, means of spread)

  In domestic livestock, animals often lick aborted foetuses, placenta and vaginal fluids and infection seems to occur through the mucous membranes of the oropharynx; animals are readily infected through the conjunctiva under experimental conditions, and this may also be a common natural route; infection can also be gained through the udder through contaminated automatic milking equipment; ingestion is also a possible route even though it needs large doses. Natural and more clearly artificial insemination may be also a mode of transmission. Congenital transmission also occurs in at least cattle, sheep and goats.Humans contract the disease by ingestion of contaminated milk or fresh dairy products, by handling infectious materials, through broken skin and aerosols.

• Occasional mode of transmission

  Infection by aerosol is occasional but highly significant in some circumstances such as slaughter houses and laboratories

• Conditions that favour spread

  Poor animal tracking, large flocks/herds, extensive breeding, transhumance, sharing common pastures, poor management practices (particularly in intensive breeding), poor hygiene, unawareness of the disease and unregulated movement of infected animals; low standards of animal sanitation and husbandry; no segregation of birthing animals and clean-up of post birth tissues and fluids; incorrect disposal of aborted foetuses and associated materials.

  In the case of ruminants (and, therefore, humans), no vaccination could be considered a main condition.

  GAPS :

  It would be convenient to allow brucellosis-free but vaccinated cattle and small ruminants some trade movements (i.e., destination feedlots and slaughterhouses). This would avoid premature abandon of vaccination.

• Detection and Immune response to infection

• Mechanism of host response

  Brucella triggers both antibody and cell-mediated responses. In primary infections, antibodies are not effective, and overcoming the infection depends largely on the cellular immunoresponse. Antibodies, however, may play a role in the protection provided by vaccines and when transferred to offspring via colostrum and milk. Brucella can invade and persist in macrophages that are in a non-activated state at the time of entry but do not seem to survive in pre-activated macrophages or when opsonized (hence antibodies in milk of infected mothers provide some degree of protection). The route of entry into these cells is therefore important. The infective strategy of brucellosis is one of stealth whereby it establishes itself into its favoured niche prior to the host raising an effective immune response. The host may respond by increasing the inflammatory action of macrophages but this may come too late. Thus, once brucellae reach intracellular niches, the development of a cell-mediated response is inefficient in clearing the infection and the disease develops. On the other hand, animals vaccinated with live vaccines develop a protective cell-mediated immunity and can control the bacteria when exposed, depending on the vaccine, size of the challenge, physiological status (sexually mature and pregnant animals are more susceptible) and possibly other factors.

• Immunological basis of diagnosis

  Detection of antibodies and/or cellular responses.

  GAPS :

  What percentage of animals that mount an immune response do not become infected.What percentage of infected animals self cure or are they infected for life?

• Main means of prevention, detection and control

• Sanitary measures

  Sanitary measures are effective at containing and limiting the spread of disease in animals, but are only effective or applicable in low prevalence situations and when appropriate budget is available. They include:

  • Culling of infected animals.
  • Separating off birthing areas from the rest of the herd and decontaminating this area once used. Ensuring that any birth or abortion material is rapidly and effectively removed is also extremely important in limiting disease spread. Rigorous cleaning of fomites also helps to limit the spread of disease.
  • Treatment of slurry with caustic soda or xylene prior to spreading may also reduce disease spread if infection is present. Brucellae are susceptible to a number of commonly available disinfectants (2.5% sodium hypochlorite, 2-3% caustic soda, 70% ethanol) that can be used to clear areas and premises.
  • Proper disinfection of milking equipment from animal to animal.

  Milk pasteurization is the most effective way to prevent human brucellosis in areas where the disease is endemic and is not controlled in the animal hosts.

• Mechanical and biological control

  Isolation of infected animals and herds via restriction of animal movements is very important in limiting the spread. Movement restrictions on animals identified as linked by epidemiological studies is also very important. The control of animals in physically and geographically linked zones is also helpful.

• Diagnostic tools

  Bacteriology

  The only unequivocal diagnostic method, especially important in non-endemic areas. Culture is slow, expensive and presents significant risks to diagnosticians. Selective media are necessary. Several selective media have to be combined for optimal sensitivity. Sensitivity depends on the type and number of samples, the amount seeded (milk or vaginal fluids in live animals; a large number of organs in necropsies), their adequate conservation and the number of bacteria in the sample. Unless optimized in these regards, sensitivity is low and culture-negative animals are not necessarily free of brucellae.Identification and typing by classical methods is difficult and only suitable in reference laboratories.

  Diagnosis by detection of Brucella DNA

  Animals.:A large gap.Humans:A few PCR and qPCR protocols have been shown to be sensitive and specific under research conditions.

  Antibody tests in infections caused by S Brucella

  Intrinsic limitations are: (a) immune-response proves exposure to Brucella but not necessarily infection; (b) these tests may fail at early stages of infection or in old or immuno-suppressed individuals. The basis of immunodiagnosis is largely down to the detection of anti-Brucella antibodies.

  Animals

  1. Smooth-Lipopolysaccharide (S-LPS) tests (including tests that use O-chain polysaccharide-core oligosaccharide LPS sections [PS]).

  Blood serum tests

  The Rose Bengal test (RBT) and the Complement Fixation test (CFT) have been standardized for the diagnosis of cattle and small ruminant brucellosis, and in combination used successfully in eradication programs.There are also iELISA assays available that are suitable for high throughput serology. Several indirect ELISA (iELISA) show sensitivity equal to that of RBT, higher than that of the CFT, can be automated, and are suitable for domestic ruminants.An iELISA for camels is available.To improve the specificity in vaccinated animals, a competitive ELISA (cELISA) has been developed but its sensitivity does not seem optimal. Because it does not depend on anti-IgG conjugates, the cELISA can be considered multi-species.A fluorescence polarization assay (FPA) is available.IgG lateral flow immunochromatographic assays (LFiC) for cattle and small ruminants have been developed and are commercially available.Specificity hampered by: (a), vaccination with Rev 1 or S19 (all S-LPS tests) or RB51 (ELISA, FPA and LFiC); (b), cross-reacting bacteria that cause false positive serological reactions (FPSR) (Y. enterocolitica O:9, E. coli O:157 and a few other bacteria) are a problem in some areas, particularly in brucellosis free countries and in pigs.Despite claims by some manufacturers, no test is able to fully differentiate infected and vaccinated animals neither false positive serological reactions (FPSR).

  Milk tests

  Tests developed include the Milk Ring Test (only suitable in cattle), and several iELISA in cattle, sheep and goats.

  2) Native hapten (NH, structurally equivalent to core free O-chains) tests.

  NH precipitation tests can differentiate the antibody responses of infected and vaccinated small ruminants and cattle in epidemiologically complex situations but show less sensitivity that RBT and iELISA.These tests give no false positive results in cattle infections caused by Y. enterocolitica O:9 and other bacteria that cross-react with the Brucella S-LPS.Of little or no usefulness in pigs.

  3) Protein tests

  Several assays with crude protein extracts/fractions or i-ELISA with cloned, immunogenic protein species have been described. They are not susceptible to false positive serological reactions caused by Y. enterocolitica O:9, E. coli O:157 and other cross-reacting bacteria. However, such assays are not commonly employed and have not been rigorously validated. Since there is evidence that anti-protein antibodies appear comparatively late with respect to S-LPS antibodies, protein test may suffer from suboptimal diagnostic sensitivity.

  Antibody tests in infections caused by B. ovis and B. canis

  These species lack the LPS O-polysaccharide and produce unstable cell suspensions that preclude implementations of tests based on the use of bacterial suspensions.Only, Gel precipitation and indirect ELISA (iELISA) with R-LPS-outer membrane protein complexes are available for the diagnosis of B. ovis/canis infections but suitable validation is pending

  Cellular immunity tests (infections by S or R Brucella)

  1) in vivo (allergic tests). Skin tests with cytosolic protein (brucelline or brucellergene) extracts have been proven useful when interpreted at herd level. Skin tests show only moderate sensitivity for individual diagnosis. Not suitable when vaccination (any vaccine type) is applied. Highly specific in cases of FPSR caused by Y. enterocolitica O:9, E. coli O:157 and cross-reacting bacteria.

  2) The laboratory measurement of cytokines (gamma-interferon) following in vitro stimulation of immune blood cells has also been tried but suffers from an unsatisfactory specificity at individual animal level. The gamma-interferon test is expensive, and there are not enough validation and sensitivity/specificity studies. Moreover, the infrastructure and organisation that is needed to get blood samples to the lab and on test in the right condition and within the right time frame makes it very difficult to do this test in an optimal way.

  GAPS :

  Bacteriology

  The antibiotic supplement necessary to prepare CITA’s medium is not currently marketed.Conventional typing should be discouraged and replaced by typing by DNA amplification (i.e., multiplex PCR kits)DNA amplification methods (including current multiplex PCR kits) need to be systematically validated for identification and typing in potentially “new” & “atypical” brucellae, and in brucellae from at least Sub-Saharan Africa and Asia in comparison to WGS.The value of MALDI-TOF-MS for Brucella species and vaccine typing remains to be established (issues: current methods and databases do not properly identify all Brucella species/vaccines and may misidentify Brucella as Ochrobactrum).

  Diagnosis by detection of Brucella DNA

  In general, current methods are expensive and inaccessible to some laboratories. Investigation of cheaper alternatives is necessary.

  Animals

  No diagnostic DNA-detection method is described/endorsed by the WOAH or the EU.The literature describes a relatively large number of PCR (primers, amplification) and DNA-extraction protocols that provide excellent analytical sensitivity and (as far as this can be tested) specificity. However, none has been properly validated for diagnostic sensitivity and specificity in cattle, small ruminants and pigs (B. melitensis, B. abortus or B. suis) with regards to host status (proven infection vs. no contact with Brucella, non-vaccinated vs. vaccinated and type of vaccine/vaccination protocol) and sample (milk, vaginal mucus, necropsy samples, etc.). Lack of validation also affects these tests in other domestic semi-domestic hosts and wildlife.For B. ovis and B. canis, there are promising results with PCR, that should be confirmed and investigated further.There are commercially available PCR kits for DNA amplification but they suffer from the same validation problems. Also, this validation problem affects the DNA extraction kits, which should be considered as an essential part of a given PCR diagnostic kit.

  Humans

  PCR and qPCR protocols need to be harmonized. Further research on their value in complications (including neurobrucellosis) and to assess recovery is necessary.

  Antibody tests in infections caused by S Brucella

  Animals

  For WOAH tests, scarcity of international standard sera.In domestic livestock:

  • no assay combines 100% sensitivity and 100% specificity when testing individual sera, particularly when vaccination with S19, Rev 1 is implemented. RBT and CF (but not other tests) are DIVA in RB51 vaccinated animals but only if they are maintained in Brucella-free environments. It cannot be ruled out that new technologies could overcome this difficult DIVA problem.
  • scarcity of validation studies for iELISA, cELISA, FPA and LFiC in domestic livestock under the conditions of endemic countries.

  Camelids:

  • because of the peculiar immunoglobulin repertoire of camelids, the usefulness of RBT and CF remains to be investigated.
  • the available camel iELISA and the cELISA remain to be validated in these animals.

  NH tests: no studies in species other than small ruminants and cattle; not commercially available.Protein tests: no studies in species other than small ruminants and cattle; not commercially available for blood serum tests.

  Antibody tests in infections due to R Brucella

  No suitable commercial tests available. As compared to S Brucella infections and in association with the lack of the S-LPS immunodominant O-polysaccharide, serological tests show less diagnostic sensitivity.Limited information on false positive reactions due to cross-reactive bacteria (a problem identified in B. ovis and B. canis)Further studies to validate iELISA kits are necessary.

  Cellular immunity tests (infections by S or R Brucella)

  Protein formulations for the brucelline skin test are not marketed.

• Vaccines

  WOAH-recommended vaccines only available against B. abortus (cattle) and B. melitensis or B. ovis (small ruminants) infections. Several attempts to produce effective subcellular or DNA based vaccines but none resulted as practical and/or effective as the current vaccines. The effective vaccines are, for the moment, live attenuated strains. New live generation vaccines have been tested, but none proven as effective as the existing ones.Currently there are significant differences in the quality of the vaccines made by different makers. Different hypothesis could be mentioned:

  • Use of Master Seed Lot not validated by Reference Laboratory.
  • There is evidence that makers in some countries directly use commercial vaccines made by others under strict registration rules as seeds for production of vaccines, thus infringing the Master Seed / Seed Lot strategy recommended by the WOAH.
  • Deficient free-drying protocols resulting in short shelf-life (progressively reduced live vaccine content and underdosing).
  • Not conform equipment and facilities are used.
  • Personnel not mastering the technology and the controls (IPC and release tests).

• Therapeutics

  Seldom used in animals. However, B. suis infection in pigs could be treated with antibiotics when the infection affects large industrial premises since depopulation is unfeasible.In humans, adults with acute brucellosis and no complications or focal disease should be treated with doxycycline-streptomycin or doxycycline-­gentamicin combinations. In focal forms, the preferred regimen is the same but duration of therapy must be individualized. Surgery should be considered for patients with endocarditis, cerebral, epidural, spleen, hepatic or other abscesses not resolving with antibiotic therapy. During pregnancy tetracyclines and streptomycin must be avoided and a rifampin monotherapy is considered the regimen of choice. Trimethoprim-sulfamethoxazole (cotrimoxazole) plus rifampin is an alternative regimen but it is contraindicated before week 13 or after week 36 of pregnancy. Children less than 8 years old can be treated with rifampin-cotrimoxazole, or rifampin or cotrimoxazole plus gentamicin. Antibiotics have to be administered for long (usually 6 weeks but sometimes longer) times. Treatment is expensive and may pose compliance problems. Relapses occur in 3-5 (possibly up to 20-30% in monotherapy) of patients. Rifampin must be avoided in countries where tuberculosis is endemic.

  GAPS :

  In general, more efficacious/cheaper antibiotics would be valued if they could:

  • avoid parenteral administration (difficult in many resource-limited settings).
  • shorten the administration period.
  • totally avoid relapses.
  • make treatment affordable.

  With regards to existing antibiotics, as simpler/cheaper alternatives that also avoid parenteral administration (difficult in in resource-limited settings) and streptomycin shortages are very interesting:

  • trials evaluating doxycycline monotherapy regimes in patients with low relapse risk (according to published data on relapse risk factors).
  • trials evaluating the duration of the gentamycin oral administration.

• Biosecurity measures effective as a preventive measure

  B. abortus, B. melitensis, B. suis and B. canis are currently in WHO Risk Group 3 (human disease). They require:

  • Biosafety level 2 practices for activities involving clinical materials of human or animal origin.
  • Biosafety level 3 containment, practices and facilities for all manipulations of cultures and for experimental animal studies.

  B. ovis is not zoonotic.

  GAPS :

  No consistent classification into risk groups across countries. For example, in some but not all EU countries B. microti, B. ceti, B. papionis and B. pinnipedialis are classified in risk group 2. This also happens with B. suis biovar 2.

  Harmonization should help research and collaboration.

• Border/trade/movement control sufficient for control

  Necessary and implemented at international level. The movement of infected animals is the main mechanism for the spread of disease between herds. Diagnostic testing procedures are in place for the movement of animals between nations which are based upon the methods described in the WOAH Manual of Diagnostic Tests and Vaccines for Terrestrial Animals.

• Prevention tools

  In areas free of brucellosis, the best preventative measure is to ensure that imported animals are disease free. This is mainly done through the application of serodiagnosis and by selecting areas for importation that are certified disease free.

  When brucellosis is present in a herd, then sanitation measures and vaccination can be put in place as described above. Where livestock are exposed to wildlife that may be carrying the disease then an effective physical barrier is the best means of prevention.

  GAPS :

  The spread of brucellosis from wildlife to livestock is not fully understood. Improved high resolution epidemiological tools would assist in such investigations.

• Surveillance

  Necessary and implemented in (developed) countries free of brucellosis. Only effective if supported by a strong veterinary infrastructure to take the appropriate samples and deliver the appropriate measures.Usually conducted through serology using the tests recognised by the WOAH. The number and proportion of animals tested need to adjusted depending on the objective of the surveillance, the historical prevalence of the disease and the threat of spread and/or introduction. An additional surveillance method is to report and examine abortions by culture to detect Brucella.When FPSR are suspected, sero-surveillance can be supported by the skin test and final confirmation of disease is sometimes only made after positive culture.

  GAPS :

  The level and type of surveillance performed across the globe (not possible where structural weaknesses exist) is very different. Frequently, it is intertwined with inconsistent vaccination programmes that interfere with the specificity of tests, using sample-sizes based on imperfect evidence and wrongly used tests, and thus significant complications ensue.

• Past experiences on success (and failures) of prevention, control, eradication in regions outside Europe

  Brucellosis is a difficult disease to control in livestock owing to several factors. Amongst these are the lack of outward clinical signs of disease other than abortion and fertility reduction meaning that detection is difficult without a sustained and expensive surveillance programme.Critical requisites for eradication are sustained vaccination programs, proficient Veterinary Services, control of vaccines, animal censuses, animal movement control, stakeholder engagement and appropriate budgets (including compensations for culling).With a few exceptions (countries with very favourable conditions), all successful control and elimination programs in cattle and sheep have been carried out with attenuated S strains, S19 and Rev 1 respectively. Vaccination is not 100% effective and is generally not capable of eradicating the disease completely. Re-introduction of disease into previously free areas can easily occur via animal movements. Without constant surveillance the disease can rapidly spread.Reservoirs of infection from wildlife that may threaten livestock also exist in some areas.The low number of countries that are completely disease free is testimony to the difficulties of eradication, prevention and control.

  GAPS :

  Control. While the tools required to control the disease in domestic livestock still have rooms for specific improvement (see 5.1.) the main obstacles relate to difficulties to achieve good vaccine coverage in many areas of the world. These difficulties have various causes, including the extensive breeding and transhumance imposed by climate in many endemic areas, usually associated with lack of censuses, difficult access to the animals, challenging conditions for veterinary services (when they exist) and overall costs out of reach for most economies.

  Eradication. The main problem is to meet the critical requisites. Implementation of test-and-slaughter policies, and misconceptions on the use of tests and vaccines when control has not been achieved are also causes of failure.

• Costs of above measures

  The costs of these measures is high. United States Department of Agriculture sources estimate that in the 1990s, on average about US$150 million was spent each year in the US.Vaccination is a more cost-effective policy than test and slaughter but as vaccination on its own is unlikely to eradicate disease in the short term, test and slaughter (with the associated compensation costs) is the only way to certify and maintain freedom from brucellosis.Due to the few clear clinical symptoms in livestock, effective surveillance requires the testing of a relatively high proportion of animals by serology. The costs of sample collection and testing alone (without including any slaughter and compensation costs) can easily extend from tens of thousands into millions of Euros per annum dependent upon population size.The costs of the serological testing are a low proportion of these costs once animal compensation and logistical costs are also weighed in.Very few studies have assessed the benefit-cost ratio of controlling animal brucellosis. For sheep (B. melitensis brucellosis) under extensive management and with a 52% protection (Rev 1 vaccination), the benefit–cost ratio for society has been estimated at 3.2 (range 2.27–4.37) when all aspects of this zoonosis are included (see 11.2.). This suggests that brucellosis control is one of the most cost-effective interventions (comparable to tuberculosis treatments).

• Disease information from the WOAH

• Disease notifiable to the WOAH

  Brucellosis (infection with B. abortus, B. melitensis, B. suis) and Ovine epididymitis (B. ovis).

• WOAH disease card available

  Brucellosis (Infection with B. abortus, B. melitensis, and B. suis)Ovine epididymitis (Brucella ovis)

• WOAH Terrestrial Animal Health Code

  Infections with B. abortus, B. melitensis, B. suis and B. ovis

  Ovine epididymitis (Brucella ovis).

• WOAH Terrestrial Manual

  Chapter 3.1.4. Brucellosis (Infection with B. abortus, B. melitensis and B. suis)

  Chapter 3.8.7. Ovine epididymitis (Brucella ovis).

• Socio-economic impact

• Zoonosis: impact on affected individuals and/or aggregated DALY figures

  Morbidity rates are very high in infected individuals but DALYs of brucellosis have yet to be estimated across endemic countries. Precise assessment of the disability weight is hampered by the non-uniform picture of brucellosis (infecting species, disease evolution and clinical picture in rural vs. urban settings, and others) and vary widely. In the literature, DALYs per case vary from 0.10 to 7.5 showing that the assessments differ widely in methodology and in assumptions concerning the impact of the different clinical forms, duration of the illness and others.

  GAPS :

  Studies with a better understanding of the variables of the disease and appraisal of their morbidity.

  For aggregated DALYs figures, reliable data on the incidence are necessary.

  Estimates of the “zoonosis Disability Adjusted Life Years” (zDALY) dual (human and animal) burden of brucellosis are scarce, and could help better prioritisation.

• Zoonosis: cost of treatment and control of the disease in humans

  Although though few specific analyses exist, it should be very high. In the EU, treatment with doxycycline-rifampicin, a minimum of €60-70; diagnosis [blood culture & serology] €240. In Spain, an average of 3.091,58€ ± 1.780,69€ per hospitalized patient (years 1997-2015). Treatment (assuming that diagnosis is correct) generally inapplicable in resource-limited countries.

  GAPS :

  Not estimated for the overwhelmingly majority of endemic countries.

• Direct impact (a) on production

  Not well documented. Estimates of the economic impact of brucellosis in livestock are not easy and they are scarce and fragmentary. The impact depends on country, breeding system, etc. Some data (costs not updated for inflation):

  USA. In 1949, in 2,100,000 infected cattle (about 20 % of the herds throughout the country) annual losses from decreased milk production, fewer veal calves and necessary replacements of dairy cows: approximately $92,000,000 (not corrected for inflation).

  In cattle, a study in Colombia estimated annual losses of $2,172,000,000 assuming a 4% prevalence.

  In the 2005-2011 period a total of €132 million euro were spent by the EU for the co-financing (50% of costs) of the brucellosis eradication programs in member states (successful in France and Spain).

  The costs of eradication and further surveillance of brucellosis free areas are huge. Some examples:The costs of the eradication program in small ruminants in Spain in 2007 were €4.5 million. In 2014 (when the disease was virtually eradicated) the cost for the bovine brucellosis eradication program in Spain was €11.6 million.The costs of the brucellosis surveillance program in France (a country free from brucellosis) were €12.5 in 2014.

  GAPS :

  Not estimated in the overwhelmingly majority of endemic countries.

• Direct impact (b) cost of private and public control measures

  Not well documented. Some data (costs not updated for inflation):

  USA, from 1956 through 1975: $866,524,579, with $415,890,421. The total cost for 1976 was $75.6 million (federal allocation, $36.8 million; nonfederal, $38.8 million). These figures do not include costs of this disease to industry and costs in the treatment of human brucellosis, physicians' fees or hospitalization.

  Spain (year 1989): average €5000/case (treatment, hospitalization and hours of work lost).

  GAPS :

  Not estimated for the overwhelmingly majority of endemic countries.

• Indirect impact

  Very high. Infected animals cannot be marketed. Several endangered breeds in some extensive breeding systems seriously affected by eradication campaigns.

  GAPS :

  Not estimated for the overwhelmingly majority of endemic countries.

• Trade implications

• Impact on international trade/exports from the EU

  Very high. Trade restrictions are placed on animals that come from non-brucellosis free regions and nations especially when trading with free nations.

  GAPS :

  It would be convenient to allow brucellosis-free but vaccinated cattle and small ruminants some trade movements (i.e., destination feedlots and slaughterhouses). This would avoid premature abandon of vaccination.

• Impact on EU intra-community trade

  Very high. Infected animals cannot be marketed. Regulations do restrict trade but are necessary to maintain freedom in free areas.

• Impact on national trade

  Very high. Infected animals cannot be marketed.

• Links to climate

  Seasonal cycle linked to climate

  In some climates, seasonal cycle is linked to the breeding cycle.

• Distribution of disease or vector linked to climate

  Present in all climates inhabited by humans. None or insignificant spread of disease by vector.

• Outbreaks linked to extreme weather

  Not really.

• Sensitivity of disease or vectors to the effects of global climate change (climate/environment/land use)

  Global warming could cause environmental changes that impact host distribution and land use leading to shifts in the distribution of the disease.

• Main perceived obstacles for effective prevention and control

  Non-technical

  • Lack of awareness of the disease and its characteristics. Very extended obstacle. This includes the existence of brucellosis, its transmission modes and zoonotic character, hygienic measures, etc.
  • Infrastructural and budgetary. Deficiencies in this broad category are widespread in resource-limited countries. This obstacle includes insufficient veterinary services and scarcity of reference laboratories in endemic countries.
  • Challenges imposed by environment and climate. These may make necessary extensive and mixed breeding and animal movements.
  • Intensification of breeding. When farms (meat, dairy) become very large, brucellosis becomes exceedingly difficult to control if possible. A clear problem in some emerging economies.
  • Inappropriate legislative measures.
  1. Not infrequently, resource-limited countries have legislation directly adopted from wealthy countries that are inapplicable or counterproductive under their conditions.
  2. In some areas where brucellosis is under control healthy vaccinated animals cannot be marketed, forcing a premature abandon of vaccination.

  Technical

  • Lack of technical laboratory capacity/knowledge for efficient diagnosis.
  • Lack of a safe melitensis vaccine for immunoprophylaxis in small ruminants.
  • Lack of vaccines / vaccine studies in yacks, water buffaloes, and camelids.

  GAPS :

  All measures that could help to reduce or solve the listed obstacles.Diagnostics and vaccines, studies in hosts other than cattle, small ruminants and pigs

• Main perceived facilitators for effective prevention and control

  Improved education/awareness.

  Capacity building, including meeting infrastructural needs.

Global challenges

• Antimicrobial resistance (AMR)

• Mechanism of action

  Mutants resistant to rifampicin and streptomycin in the known targets of these antibiotics can be obtained by repeated passage on antibiotic-containing media. However, their natural occurrence is highly questionable:

  • Not found in studies that investigated Brucella isolated from relapsed patients.
  • There are reports on the development of resistance of Brucella to the antibiotics used to treat human brucellosis (streptomycin [or gentamycin], doxycycline and rifampicin) but claims are based on in vitro methods that are not reliable to test Brucella antibiotic resistance.
  • The overwhelmingly majority of these claims are not supported by identification of relevant mutations in antibiotic targets.

  GAPS :

  Considering the misuse of antibiotics in animals in endemic countries, investigation of possible resistances is advisable. Such an investigation should always include a molecular demonstration/identification of the potential mechanism and subsequent testing in vivo in laboratory models.

• Conditions that reduce need for antimicrobials

  Controlling/eradicating the disease in animals and hygienic measures such as milk-pasteurization reduce/abrogate human infections and, therefore, antibiotic use.

• Alternatives to antimicrobials

  None (there are unsupported claims on the usefulness of plants, probiotics and Chinese traditional medicine).

• Impact of AMR on disease control

  None.

• Established links with AMR in humans

  None known

• Digital health

• Precision technologies available/needed

  Scarcely or not necessary.

• Data requirements

  Scarcely or not necessary.

• Data availability

  Scarcely or not necessary

• Data standardisation

  Scarcely or not necessary

• Climate change

• Role of disease control for climate adaptation

  Control/eradication of brucellosis in draught-resistant ruminant breeds and camelids would help to sustain animal production in areas where impact of global warming is predicted.

• Effect of disease (control) on resource use

  Control/eradication have a large positive impact on animal production and allocation of resources to other goals. The same for human healthcare resources.

• Effect of disease (control) on emissions and pollution (greenhouse gases, phosphate, nitrate, …)

  None.

• Preparedness

• Syndromic surveillance

  Systematic surveillance (only syndromic in part) is implemented in the USA, Canada, EU countries, Australia, New Zealand and Japan.

  GAPS :

  Not implemented in the vast majority of endemic countries. Preparedness to meet challenges by this zoonosis (and others) practically non-existent in many African countries and limited in several Latin American countries and Asia.

• Diagnostic platforms

  None/Not applicableNone/Not applicable.

• Mathematical modelling

  Several mathematic models including variables like host species, transmission, climate and vaccination have been published. Some directed to evaluate costs support the benefits of vaccination. For other purposes, the models give no new insights on the otherwise well-known effects of these variables on the dynamics of disease and risk factors.

  GAPS :

  Questionable usefulness/necessity with regards to prevention/preparedness.

• Intervention platforms

  None/Not applicable.

• Communication strategies

  Brucellosis by B. abortus, B. melitensis, B. suis and B. ovis are notifiable diseases recorded in the Word Animal Health Information Systems (WAHIS) and in the Animal Diseases Information System (ADIS) for the EU.

  GAPS :

  Human brucellosis is not a notifiable disease in most endemic countries.For most endemic countries records in the WAHIS are not dependable because of the infrastructural weaknesses of these countries.

Main critical gaps

• (The order in the lists does not reflect priorities)

  General

  • A better understanding of the virulence and mechanisms of pathogenicity to design better vaccines and treatments.
  • New Brucella species: importance, epidemiology, virulence, antigenic structure.
  • Studies on human incidence and clinical presentations according to Brucella species and socioeconomic conditions
  • More efficacious/cheaper antibiotics and further trials on monotherapy with doxycycline and on streptomycin replacement by gentamycin.

  Diagnosis by detection of Brucella DNA

  In general, current methods are expensive and inaccessible to some laboratories. Investigation of cheaper alternatives.

  Animals

  • Validation studies of commercially available PCR kits for DNA amplification and DNA in all domestic hosts and wild-life.

  Humans

  • Value in complications (including neurobrucellosis) and to assess recovery. Harmonization?

  Serological diagnosis

  • Studies in hosts other than cattle, small ruminants and pigs.
  • Validated tests for R brucellae

  Vaccines

  • Safety of conjunctival administration of S19 in bulls.
  • Safety and efficacy of S19 in yacks, camels and water-buffaloes.
  • A safe vaccine against melitensis infection of small ruminants.
  • A ovis specific vaccine.
  • A suis vaccine for pigs (may be necessary when domestic pigs are from endangered breed and bred outdoors or extensively in contact with wild-boars).
  • A vaccine for camels.
  • Re-considering current Genetically Modified Organism EU legislation.

  Epidemiology

  • Role of wild-life as reservoirs.

Conclusion

• Although tools to control the disease are available and are effective if properly and rigorously applied, safer, more effective and cheaper tools are needed. Current costs of eradication are unsustainable for most economies where brucellosis is prevalent. This implies research on improved molecular diagnostic protocols; the performance of serological tests in camelids, yaks, water buffaloes and wildlife; a B. ovis specific vaccine; and socio-economic studies under different situations are required to prioritize interventions in developing countries.

  The epidemiology, diagnosis and immunoprophylaxis of brucellosis in less common livestock species needs further investigation.

Sources of information

• Expert group composition

  Ignacio Moriyón, University of Navarra, Spain – [Leader]

  Raquel Conde-Álvarez, University of Navarra, Spain - [co-Leader]

  Bernat Canal, Gold Standard Diagnostics Madrid

  Ana Cristina Ferreira, Instituto Nacional de Investigação Agrária e Veterinária, (INIAV, IP), Portugal

  Gabriela Hernández Mora, Servicio Nacional de Salud Animal (SENASA), Costa Rica

  Falk Melzer, WOAH Reference Laboratory for Brucellosis, Friedrich-Loeffler-Institut (FLI), Germany

  Gabriel Moyano, ZENDAL – CZ Vaccines

  Pilar Muñoz, CITA de Aragón, Unidad de Tecnología en Producción y Sanidad Animal, Spain

• Date of submission by expert group

  11 July 2024

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