Development of multispecies validated serology protocols for complex ecosystems, focused on East Africa, in support of Global PPR eradication

Lead Research Organisation: Royal Veterinary College
Department Name: Pathobiology and Population Sciences

Abstract

Peste des petits ruminants virus (PPRV) causes severe disease in sheep and goats, hampering sustainable livestock production and significantly contributing to human poverty and food insecurity in >70 countries majority of which are ODA where it occurs. Consequently, the Food and Agriculture Organisation is coordinating an international effort to eradicate PPRV globally by 2030. PPRV infections also occur in wildlife, which has resulted in severe disease and mass mortalities in Asia and Middle East, including in rare and endangered species underlining significant impacts of this virus upon biodiversity. In Africa, research has shown that wildlife (specifically hoofed mammals like buffalo and gazelle) can become infected with PPRV but do not exhibit clinical disease. Therefore, determining infection rates where healthy animals are infected relies on detecting anti-PPRV antibodies in the animals' serum, i.e. blood testing. Better understanding of PPRV epidemiology in wildlife is critical for the success of the Global PPRV Eradication Program, for example, whether PPRV spills over into wildlife from infected livestock or whether wildlife can spread and maintain PPRV in an asymptomatic state. To answer this question in the GCRF PPR we collected sera from buffalo and Grant's gazelle using randomized sampling in order to obtain an indicationof the true PPRV seroprevalence across the Greater Serengei ecosystem, a complex PPRV-endemic ecosystem, inclusive of both National Park and mixed wildlife livestock areas like the Ngorongoro. In mixed systems the PPR has significant impacts in small ruminants and associated livelihoods and infects multiple host species. Our initial analysis of the wildlife sera from the GCRF and earlier studies under BBSRC ANIHWA indicated that current serological tests (such as ELISA) may not perform adequately with samples from atypical wild hosts compared tosheep and goats. This current project seeks to address the clear need, highlighted by our GCRF study and now by global policy-makers at FAO, to examine availableserological tests in wildlife species, to compare their performance, determine cut-offs for endemic countries. To achieve this, our project brings together expertise from Europe (Royal Veterinary College, ; University of Glasgow, Pirbright Institute, UK; IAEA FAO Joint Division Seibersdorf, Germany, , CIRAD, France) and our ODA partners in Tanzania (SACIDs SUA, Tanzania Wildlife Research Institute, Kenya Wildlife Service). Two novel diagnostic tests, which have clear practical advantages over other existing tests, and which have been developed and published by European partner labs, will be shared and evaluated against a panel of sera at an especially convened workshop of all partner laboratories at IAEA in Austria. These sera will include aliquots from ELISA and VNT tested sera to be provided by Pirbright. These tests will then be transferred to partner laboratories and the regional centre in SACIDs SUA. Training, test set-up and testing of the sera will be done at SACIDS SUA to achieve the second and key objective of establishing a regional PPR research laboratory in eastern Africa. Analysis of the GCRF sera with the new testing protocol provide accurate epidemiological information on PPRV infection rates in wildlife within the Greater Serengeti ecosystem to inform effective routes to PPRV control and eradication. We will publish new test protocols for PPRV in atypical hosts and engage with OIE and FAO to promote these as a standard in the Global PPRV eradication programme. The main outcome of this project will be improved capacity in PPR research and surveillance, in a critical region for PPR persistence, enable use of atypical hosts as sentinels of infection and, inform on the potential risk of disease in wildlife and other hosts to the Global Eradication strategy

Planned Impact

Peste des petits ruminants (PPR) is a highly contagious viral disease of sheep and goats. PPRV remains endemic in many low and middle-income countries in Asia, Middle East and Africa. It causes USD 1.5 to 2 billion in losses each year where 80% of the world's sheep and goats feed and provide livelihoods for more than 330 million of the world's poorest people. PPR affects communities vulnerable to climate change and drought and is the next priority in global veterinary disease control poverty alleviation.The estimated expenditure on vaccination ranges from USD 270 to 380 million. The annual impact of PPR is estimated at between USD 1.45 and 2.1 billion per year. Approximately a third of the global financial burden of PPR is borne by Africa. OIE and FAO are both actively engaged in control policies for PPR throughout the world and have initiated a global eradication programme with a target of 2030 to remove this burden. Recently PPR has spread to the European part of Turkey and Bulgaria threatening Europe. It is possible that wildlife present in Europe, may spread the disease. The EC is concerned about this and recognises the potential role of wildlife in PPR spread. The undiscounted costs for a fifteen-year global control strategy (FAO and OIE) are between USD 7.6 and 9.1 billion, with the first five years costing between USD 2.5 and 3.1 billion. (http://www.fao.org/3/a-i4460e.pdf). Although the PPR eradication programme aims to eradicate the disease worldwide by 2030, little is known about the role of wildlife and atypical domestic hosts such as cattle. Lack of epidemiological understanding may risk failure of the strategy or increase substantially the cost of eradication. A better understanding of PPRV epidemiology in wildlife has been cited as a clear research priority to underpin successful PPRV eradication and this research will therefore provide tools and evidence to support political will in the global eradication process. The GCRF PPR project provides the foundation for demonstrating the elimination of PPR virus (PPRV) from a large complex multi-species ecosystem as pre-requisite for global eradication. This translation award will enable the findings to strengthen partnerships, improve test protocols, and develop surveillance and control methods for the next PPR Global Eradication Programme (2022 - 2027). An expert working group at FAO in March 2019 suggests incorporating wildlife across the 4 main components of PPR GEP, specifically highlighted validation of serological tests in atypical species as a research priority. A key step is to ensure capacity to understand epidemiology in complex ecosystems and a robust platform for verification of elimination after effective vaccination of sheep and goats. Our proposal provides a case with clear public good that will support the large economic and infrastructural investment concomitant with the eradication pathway. The project will provide valuable development assistance to a nascent research laboratory emerging in East Africa, with great potential to support veterinary services in ODA countries and consolidate more local capacity in dealing with these critical emerging diseases before the disease can threaten remotely. PPR was not so much a global issue a decade ago. Lack of local governance and weak local investment in health services and systems are to blame for the spread of PPR. The impact of improved tests, greater integration of disciplines (One Health) and upgrading local capacity saves money. Elucidating the role of atypical hosts in PPR epidemiology, supports UK policy on food security, major investment in developing countries working towards PPR control. It will strengthen multidisciplinary collaborations between science and industry, virology,, epidemiology and biodiversity conservation. The complementary partnership will diversify the impact, broadening scientific outreach and provide channels to influence both policy and the implementation of disease control.

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