Serological survey for foot-and-mouth disease in wildlife in East Africa and parameter estimation of the Cedi test NSP ELISA for buffalo

University of Edinburgh, Centre for Tropical Veterinary Medicine, The Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, EH25 9RG, United Kingdom; Institute for Animal Health, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom; Pan African Programme for the Control of Epizootics, P.O. Box 30786, 00100, Nairobi, Kenya

^* To whom correspondence should be addressed. Email: satya.parida{at}bbsrc.ac.uk.

	Abstract

In this study we estimate the seroprevalence of FMD in wildlife from East and Central Africa. Sera were sourced from between 1994 and 2002 from a Rinderpest surveillance programme. Our study compared a non-structural protein ELISA (Cedi test) with a virus neutralisation test. The study shows that there is only a low seroprevalence of FMD in sampled non-buffalo species. The seroprevalence in the Cape buffalo was high for SAT2, lower for SAT1 and lowest for SAT3. As SAT2 serotype was most prevalent the Cedi test largely reflected the occurrence of SAT2 positive animals. The results also suggest that SAT2 became dominant around 1998 with a large increase in seroprevalence. The sensitivity and specificity of the Cedi test were estimated by comparison to the combined VNT results from all three SAT tests. A Bayesian implementation of the Hui-Walter latent class model was used to estimate the test parameters. The model permits estimation in the absence of a gold standard test. The final model using non informative priors and assuming conditional independence of test performance estimated Cedi test sensitivity at 87.7% and specificity at 87.3%. These estimates are similar to those in domestic bovines; they suggest that the Cedi test is a useful tool for screening buffalo for multiple serotype infections of FMD.