Kits are available for use in main laboratories.
Available tests can be retrieved here (Source: DiagnosticsforAnimals).
- Kits available are at high cost for developing countries- One Lateral flow device available and a new one soon to be commercialized.
- Development of molecular penside test is needed.
- New kits are being commercialized without proper validation, increasing the risk of misdiagnosis. Labs need to get information and training as necessary from reference lab before purchasing a new kit.
Commercial diagnostic kits available in Europe. Member states’ national reference labs are trained by EU reference labs in PPR diagnostics.
Commercial available diagnostics can be found here. (List provided by DiagnosticsforAnimals)
Immunocapture kit for PPR antigen detection and PPR competitive ELISA test for serological assessment indicated in OIE Manual.
GAP: Immunocapture kit for PPR antigen detection an PPR competitive ELISA test indicated in OIE Manual but not yet recommended as prescribed test for international trade.
Methods are described in the OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2013:
Identification of the agent / Antigen detection:
- Indirect fluorescent antibody test
Virus isolation and identification:
- In primary lamb kidney cells, VERO or VERO Dog-SLAM cell line
- Electron microscopy
Virus RNA detection:
- Amplification by polymerase chain reaction (classical RT-PCR and quantitative RT-PCR assays available
- Virus neutralisation
- Competitive ELISA
- Immunodiffusion inhibition test
GAP: New cell line expressing the PPRV receptor is available for efficient isolation of PPRV not yet described in the OIE Manual (but is indicated in inserted in the new edition of the Manual to come out probably in 2018).
There is a risk of emergence of the disease in Europe. Reference laboratories need to purchase kits to be prepared in case of emergence.
Not available, but some DIVA vaccine prototypes and companion ELISA tests under development.
These tests will be important to provide meaningful assessment of vaccine coverage and epidemiological surveillance where the virus is circulating. This will be especially important for the last stages of the eradication programme and for countries to get disease-free status faster.
GAP: DIVA vaccine and companion tests needed.
The global PPR eradication campaign organized by OIE/FAO has increased the interest of government and private companies in financing development of new tools because the market opportunity has increased. Main interests are in penside tests, non-invasive tests for wildlife, and DIVA tests.
Markers of PPR virulence and of host susceptibility, notably to evaluate risk when emerging in a new area, i.e. Mongolia.
Detection in fomites and other environmental material.
Live attenuated PPRV vaccine is available from more than 20 vaccine production companies and government laboratories in Africa, the Middle East, Asia and Turkey. OIE launched international call for tender to create vaccine banks in particular for Africa.
GAP: Maintain on the long term vaccine banks to ensure the availability of sufficient stocks (emergency or global strategy) as supply is subject to supplier’s rapidity in replying. In addition, ensure certified quality of the batches used for vaccine banks.
None, but use of certified, quality controlled PPR vaccines could be authorized in infected and at-risk European countries as for LSD.
None, but DIVA vaccine prototypes in development.
GAP: Needed to reduce resource burden during final sero-monitoring stages of eradication and obtain OIE disease-free status most rapidly.
Animals vaccinated with the current live attenuated vaccines for PPR have a good immunity which may last for at least 3 years but cannot be distinguished serologically from infected animals. A cold chain is required for transport and storage of PPR vaccine. Stability of vaccines in lyophilized form and when resuspended vary among producers. Vaccines highly stable in lyophilized form are being tested in the field. Most vaccines are efficient for only 2-3 h after resuspension, but some can be used for up to 24 h. Not all vaccines produced go through strict quality control procedures, so effectiveness of vaccines may vary.
Risks associated with PPR vaccine quality control need to be evaluated. Strict standard quality controls are needed for all vaccine produced. Buyers need to be informed of the issues with quality control so they can ask for information from producers.
Buyers need to know about stability of vaccines so they can purchase vaccines most appropriate to their regional conditions.
EU is creating a PPR vaccine bank to be prepared in case of emergence. Some member states may prepare their own vaccine bank as well. Although no vaccine has yet been authorized, use of PPR vaccines could be authorized in infected and at-risk European countries as for LSD.
DIVA vaccines are genetically modified viruses, so these products have to go through strict regulatory challenges before approval.
In principle it is possible to use vaccination as a barrier between free and endemic countries or zones although the movement of sheep and goats may render this unsuccessful. Availability of DIVA vaccines would make this option more likely, as countries would not lose their disease-free status.
The global PPR eradication campaign organized by OIE/FAO has increased the interest of government and private companies in financing development of new vaccines because the market opportunity has increased.
Prototypes in development or in process of validation:
- Recombinant capripox-based PPR vaccine able to protect against both capripox and PPR;
- DIVA vaccines;
- Conventional live attenuated vaccine with high thermo-stability in lyophilized form is being validated.
GAP: Information on the real potential of prototypes in development is still limited because no data has been published.
There is no therapy for PPR.
GAP: Use of antibiotics with fluid therapy and vaccination has been suggested to reduce the morbidity and mortality that result from PPR induced immunosuppression and development of opportunistic bacterial infections. Vitamin supplementation has proved useful for other morbillivirus infections.
Potential for pharmaceuticals is nil as EU regulations do not allow treatment of PPR-infected animals.
A couple of reports have been published on RNAi to cure PPRV from infected cells. Their interest is purely scientific.
Tests need to be sensitive and specific to PPR. Careful choice of target molecule, and high quality reagents and production are necessary. Validation of new tests must be undertaken both in the laboratory and also under field conditions in countries where the disease exists. Ideally, reference laboratories should be involved in this validation.
GAP: New diagnostic tests are being commercialized without proper validation. Laboratories have to be aware of this issue. Quality management systems are likely required to ensure confidence in testing.
Time and costs depend on the type and nature of the test. Proof of concept and the development of a new test will take time as will the validation necessary before the new tests are accepted as a diagnostic tool by the international organisations. Further time will elapse before the tests are commercially available.
GAP: New diagnostic tests are being commercialized without proper validation. Laboratories have to be aware of this issue.
This is time and labour consuming. Cooperation between all parties involved from discovery to commercial availability will be crucial.
GAP: New diagnostic tests are being commercialized without proper validation. Laboratories have to be aware of this issue.
Penside tests (antigen and molecular); non-invasive tests for wildlife and environment, DIVA vaccine and appropriate companion tests (ELISA + penside).
An antigen penside test is already available but its sensitivity appears lower than PCR (unpublished data). Tests with improved sensitivity (and high specificity) are needed.
Tests to evaluate PPR virulence and host susceptibility, notably to evaluate risk when emerging in a new area, i.e. Mongolia.
Detection in environmental DNA.
Tests are available to determine virus freedom: immunocapture test and gene amplification assays for antigen and nucleic acid detection; competitive ELISA for antibody detection.
Any new vaccine has to show at least the same efficacy, innocuity and long-term protection as existing vaccines. Improvements would target:
- increased stability in lyophilised form;
- increased stability in reconstituted form;
- recombinant vaccine targeting two or more diseases;
- DIVA vaccine.
GAP: All these avenues of development are being researched but information on their success is still limited.
10 years for development, clinical trials and licensing is realistic.
Rough estimate: 10 million EUR.
- Increased stability in lyophilised form: highly thermostable vaccine is being tested in the field. Such stability should be targeted by all producers to increase efficacy of vaccine delivery in remote areas.
- Increased stability in reconstituted form: some vaccines available are stable for up to 24hrs. Such stability should be sought by all producers to increase efficacy of vaccine delivery in remote areas.
- Recombinant vaccine targeting two or more diseases: PPR/Capripox recombinant in development.
- DIVA vaccine: prototypes in development/validation.
There is limited interest as EU regulations do not allow treatment of PPR-infected animals.
None at present.
- Difficulties in the control of movements of affected and more importantly incubating animals across regions and borders.
- Problems of differentiating infected from vaccinated animals.
- Quality of vaccines varies a lot because of lack of standard quality control measures.
- Issues with vaccine delivery to farmers, vaccine application in some environments and proper storage over long period of time.
- Differential diagnosis of PPR-like diseases.
Virus family Paramyxoviridae, genus Morbillivirus, Species: Small ruminant morbillivirus. Antigenically close to rinderpest virus. Other members of the genus include measles virus, canine distemper virus and phocine distemper virus of sea mammals (seals).
Four genetic lineages (lineages 1-4) of PPR virus have been identified, but only one serotype. Lineages I and II are restricted to West and Central Africa. Lineage III is found in East Africa and sporadically on the Arabian peninsula (including historically Oman, Yemen (1980s) and more recently Qatar (2010). Lineage IV is found in Asia, Middle East, and Africa. High variability in virulence among stains across all four lineages. Host susceptibility also varies among species and breeds, and appears to be strain-dependent.
GAP: Variability in virulence and host susceptibility poorly understood.
The virus is susceptible to most disinfectants, e.g. phenol, sodium hydroxide but can survive for long periods in chilled and frozen tissues. There is little information on the virus survival in the environment. According to one study, PPRV would have a half-life of approximately 2 h at 37°C. It may survive more than a week at 4°C. The virus is stable between pH 5.8 and 9.9.
GAP: Lab and field studies required, especially in cooler climates, and in matrices likely to be implicated in transmission (water, mud, fecal matter).
- Awareness, involvement of livestock keepers/community leaders in planning and implementing prevention and control.
- Adequate animal health service delivery system at field level.
- Fast and robust diagnosis, Easy methods for surveillance in remote areas.
- Development of DIVA vaccine, vaccine stable for long periods at relevant temperatures in lyophilized form, vaccine stable for >24h at relevant temperature once reconstituted.
Main hosts are goats and sheep, but a large number of species of the order Artiodactyla, both wild and captive, have been reported with clinical signs or antibodies against PPR. Notably it has been shown that pigs can excrete and transmit PPRV. No carrier state has been identified, but sub-clinical infections can be common in wild and domestic populations where PPR is endemic, representing a risk of disease transmission.
GAP: More work needed to understand the role of Artiodactyla other than sheep and goats in the epidemiology of PPR. In particular the role of large ruminants and camelids in the epidemiology of the disease is of note.
GAP: Work is underway to determine the role of wild Artiodactyla and water holes in virus transmission. Survival in the environment is of importance (fomites etc.).
Sick goats and sheep generate aerosols containing infective droplets. Successful transmission usually requires close contact between sick and healthy animals. The risk of indirect transmission is not yet well understood, but it seems that it may happen at least during a short time frame.
GAP: Lab and field studies required, especially at wildlife-livestock interface, and in matrices likely to be implicated in transmission (water, mud, fecal matter).
Acute PPR infection is characterised by severe pyrexia, nasal discharge, lacrimation, erosive lesions on different mucous membranes and particularly in the mouth, diarrhoea and pneumonia. Animals rapidly become very dull, with sneezing and lip-licking, followed by salivation due to mouth lesions and severe diarrhoea. Many animals will die and any survivors will be in poor condition for a prolonged period and susceptible to other diseases. Can frequently be per acute in young goats. Sub acute and chronic cases may be frequent in some areas where the disease is endemic, depending on host susceptibility and virus strains. Asymptomatic PPR or circulation of mild disease complicates the epidemiology of PPR.
Mortality and morbidity can be very high in a naïve population (up to 100%) but can be lower than 15% in local breeds in regions where PPR is endemic.
The incubation period is 4–6 days, but may range between 2 and 10 days.
Mortality rate can be as high as 100% in naïve population, but lower than 15% in in local breeds in regions where PPR is endemic.
Shedding via nasal and lachrymal discharges, saliva, fecal matter, and milk. Viral material can be detected in excretions as early as 4 days post infection, and in some cases as long as 21 days post infection.
GAP: Assessment of conditions for an effective and successful transmission of the disease (minimum time required). Potential role of fecal matter important to define as agricultural practises may inadvertently increase transmission risk.
The initial site for virus replication is observed within the tonsillar tissue and lymph nodes draining the site of inoculation. It has been proposed that the virus infected immune cells within the respiratory mucosa would migrate to the local lymphoid tissue, where primary virus amplification would occur, with the virus then entering the general circulation. PPRV is highly lymphotropic and infection often leads to a profound immunosuppression that causes leucopoenia and reduced antibody responses.
GAP: More studies on the immune suppressive effect of PPRV needed.
There are no reports of PPRV affecting humans.
Acute PPR is a severe welfare problem in terms of the disease syndromes it causes.
Spill-over from livestock to endangered Saïga antelopes resulted in massive mortality (several thousands) in Mongolia. Other wild ungulates were affected during this outbreak. Wild species in disease-free countries should be considered at risk in case of PPR emergence.
Mortality due to PPR has never been observed in wild species in Africa, but this matter needs more investigation.
GAP: Further understanding in difference in susceptibility among wild species is needed to evaluate the risks for each species.
Yes in free countries and free zones.
PPRV is currently distributed in most of Africa, except Southern Africa, in the Arabian Peninsula, throughout most of the Near East and Middle East, and in countries located from Central Asia to China. It is endemic in Turkey, close to the Europe Union. There have been outbreaks in Georgia and Mongolia in 2016/2017, where the disease had never occurred before.
There is limited information on possible presence of PPRV in the Balkan region due to lack of surveillance.
More sequencing of old and currently circulating strains to understand the evolutionary dynamics of PPRV.
In sub-Saharan Africa, PPR cycles endemically in the extensive small ruminant production systems. Transhumance annually introduces the virus into immunological naïve herds and flocks south of the Sahel with disastrous results.
Each year, females give birth to 1.5-2 offspring which means that every year over 50% of the SR flocks are naïve and fully susceptible, even in endemic countries.
Related to many factors but mainly availability of grazing, which influences movement of animals and inter-flock/herd contact.
In order to derive an estimate of the potential ranges of speed of propagation, outbreak data of PPR in Tunisia as reported to the World Organisation for Animal Health (OIE) were used in an EFSA report to plot temporal and spatial linkages between outbreaks. According to this, the median speed of propagation was estimated to be 3.9 km/day, with a 95 % confidence interval of 0.3 to 65.5 km/day. Nevertheless, this result should be interpreted with caution without direct extrapolation to the potential epidemiological behaviour of PPR if it entered the EU.
- Identification and definition of risk factors for disease spreading and the communication of these data with the farmers will be important.
- Veterinary awareness of PPR as a differential in small ruminant syndromes is of importance.
- Modelling of transmission dynamics, notably in multi-species systems.
The increase of animal movement for commercial and trade purposes (e.g. the massive imports of small ruminants to the Middle East), transhumance and nomadic customs along with extensive farming practices have all contributed to the global spread of PPR.
Emergence in EU may occur via illegal importation of animals, notably from North Africa or Turkey. Movement of wildlife (e.g. wild deer) throughout Europe may also play a role in disease emergence and spread.
The fact that both PPRV lineage IV, lineage of Asian PPRV strains, and lineage III, East African PPRV lineage, have been found in the Middle East indicates that many sources of infection in this region are probably infected sheep and goats imported from both Asia and East Africa. Likewise, outbreaks in Georgia and Mongolia have been liked to East Africa and China, respectively. Phylogenetic data show that PPRV transboundary movement is frequent.
- Combined analysis of phylogenetic data and data on animal trade to better understand transboundary transmission dynamics.
- More surveys in the field needed to estimate importance of transboundary movement, especially transhumance.
- Further understanding in difference in susceptibility among wild species is needed to evaluate their role in transboundary movement of PPR.
Seasonal variations: more frequent outbreaks during the rainy season or the dry cold season in sub-Saharan Africa. Transmission cycles will vary with area/production system (movement for water/grazing; return to villages, seasonality of breeding).
Only due to drought and the need to search for food.
Direct contact through aerosol spread.
GAP: Transmission via milk has to be studied.
None known. Indirect transmission through water, mud and fecal matter is possible, at least over short term (in communal water holes for example).
GAP: Lab and field studies required to determine the risk of indirect transmission.
- Transhumance and trade movement of infected animals.
- Important social gatherings (e.g. Islamic celebrations).
- Sharing sources of water and grazing (livestock and wildlife).
Maternal antibodies against the virus can be detected in young animals and remain able to neutralise virus for three to four months providing a level of protection in newborn animals. Cellular and humoral immune responses are induced upon infection. Cell-mediated and humoral immune responses against the virus are mainly directed against the H, F and N proteins.
Sheep and goats that recover from PPR develop an active immunity against the disease. Seroconversion appears typically 4 days after infection. Antibodies have been demonstrated 4 years after infection suggesting that immunity is probably life-long.
Goats and sheep infected with PPRV develop antibodies that may be demonstrated to support a diagnosis by the antibody detection tests. The OIE recommended test for trade purpose is the virus neutralisation (VN) test. However, the competitive ELISA is currently the serological test the most routinely used.
In Europe affected animals would have to be slaughtered, and a 3km protection zone and 10 km surveillance zone set up around the infected premises.
Eradication is recommended when PPR appears in new areas. Methods that have been successfully applied for rinderpest eradication would be appropriate for PPR. These should include quarantine, slaughter, and proper disposal of carcasses and contact fomites, decontamination, and restrictions on importation of sheep and goats from affected areas.
Disease control measures would be put in place including ring vaccination or mass prophylactic vaccination depending on the situation in individual countries, and on risks to endangered captive and wild species.
In free zones, slaughter of affected flocks
Disposal of carcasses.
Detailed epidemiology to identify origin and potential spread.
Virus isolation is important. But the Immunocapture enzyme-linked immunosorbent assay (ICE-ELISA), and the nucleic acid amplification are the most currently used diagnostic tests for PPRV identification. Serological tests can also be used, the competitive ELISA and virus neutralisation.
There are homologous live attenuated PPR virus vaccines. The attenuated PPR Nigeria 75/1 vaccine strain is most widely produced and is commercially available from over 20 producers. DIVA vaccines are being developed /tested. Vaccines highly stable in lyophilized form are in field trial. Recombinant PPR/Capripox vaccine in trial.
Avoiding inter-flock contacts can help control the disease, which is possible in sedentary systems but difficult in mobile systems.
Import controls on live sheep and goats. In the event of an outbreak in a free country or region movement controls would be imposed on the infected, protection and surveillance zones.
Rules on imports of live animals.
Surveillance in infected zones and surrounding areas is paramount for early detection. Effective surveillance requires veterinary awareness, outbreak reporting, investigation and active clinical surveillance with diagnostic confirmation. This is rarely the case in countries where PPR is endemic.
GAP: There is a need for educating EU vets / farmers on the clinical expression of PPR: in case of incursion in the EU, it will be critical to have the disease readily identified (or at least suspected).
The lessons learnt from the PPR epidemics in Morocco are that PPR can be controlled in areas, such as Northern Africa, through mass vaccination campaigns implemented at the national level, provided that adequate means are available and correctly implemented. However, in endemic areas, assiduous vigilance is needed because there is a risk of PPR reoccurrence, especially with risk factors of continuous introduction such as the illegal cross-border movements of livestock. In general, early detection of (re)occurrence is a necessary condition for rapid response and the effective management of possible outbreaks of PPR.
GAP: Modelling of vaccination strategies adapted to each system, notably in multi-species systems.
A new tool, VacciCost – has been developed to estimate the resource requirements for implementing livestock vaccination campaigns. For PPR, it was estimated that the average resource requirements for undertaking 7.9 million vaccines against PPR ranged between USD 1.5 million and 2.7 million, depending on the scenario applied.
It has also been calculated that the total estimated undiscounted cost of the global eradication programme would be USD 3.08 billion. Results of a benefit-cost analysis suggest strong economic returns from PPR eradication. Based on a 15-year programme with total discounted costs of USD 2.26 billion, we estimate discounted benefits of USD 76.5 billion, yielding a net benefit of USD 74.2 billion.
Yes, via this link.
Economic losses are due to loss of milk production, loss of body condition, reduced market value, death and abortion.
It has been estimated that there are 37.4 million PPR-associated sheep and goat deaths each year (minimum 20.2 million, maximum 67.7 million), with a most likely total value of USD 1,475 million, that could be as low as USD 794 million or as high as USD 2.7 billion.
The large number of small ruminants reared in endemic areas, makes PPR a serious disease threatening the livelihood of poor farmers. The presence of disease can limit trade, export, import of new breeds and the development of intensive livestock production. PPR is a major constraint on the availability of protein for human consumption as well, and represents a threat to food security. Important impact on livelihood and economic stability for low-income farmers as small ruminants provide the day-to-day cash flow for expenses in education and health amongst other sectors.
PPR virus infection has for many years been one of the most important constraints to the increased production of small ruminants in sub-Saharan Africa.
In the case of free countries, movement controls imposed on the country or region. In endemic countries, prohibition on exports of live sheep and goats. Standards for the control of movements are contained in the OIE Terrestrial Animal Health Code.
Movement controls and trade restrictions within the EU.
Local movement controls imposed on movement from the protection and surveillance zones.
The PPR situation in countries bordering the EU emphasises the importance of implementing and maintaining appropriate control measures with regard to illegal imports and animal movements to mitigate risks. Equally the tools necessary to control and eradicate any incursion into the EU must be available. As this is one of the most economically important diseases in developing countries the development of improved vaccines with the appropriate tests to differentiate vaccinated from infected animals is vital.
1. The PPR situation in countries bordering the EU emphasises the importance of implementing and maintaining appropriate control measures with regard to illegal imports and animal movements to mitigate risks. Equally the tools necessary to control and eradicate any incursion into the EU must be available.
2. PPR is one of the most economically important diseases in developing countries. There is now a global effort to eradicate PPR. Filling the gaps in our knowledge of the disease and development of new diagnostic tools and new vaccines will increase our chances to reach this goal. Importantly, regional coordination and involvement of all stakeholders will be paramount to success. Cooperation of EU member states and European commission should be encouraged.
Names of expert group members are included where permission has been given.
Arnaud Bataille, CIRAD, France - [Leader]
Geneviève Libeau, CIRAD, France
Renaud Lancelot, CIRAD, France
Alex Caron, CIRAD, France
Adama Diallo, CIRAD, Sénégal
Bryony Jones, Royal Veterinary College, UK
Bernd Hoffman, Friedrich Loeffler Institute, Germany
Satya Parida, The Pirbright Institute, UK
Loïc Comtet, IDvet, France
Claude Hamers, Boehringer Ingelheim
6 December 2017.
World Organization for Animal Health (OIE) OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2017; http://www.oie.int/en/international-standard-setting/terrestrial-manual/access-online/
World Organization for Animal Health (OIE) OIE Terrestrial Animal Health Code 2017; http://www.oie.int/en/international-standard-setting/terrestrial-manual/access-online/
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Tago D, Sall B, Lancelot R, Pradel J. 2017. VacciCost – A tool to estimate the resource requirements for implementing livestock vaccination campaigns. Application to peste des petits ruminants (PPR) vaccination in Senegal. Preventive Veterinary Medicine 144:13-19.
Project Management Board.