Investigations into the cause of foot-and-mouth disease virus seropositive small ruminants in Cyprus during 2007

In 2007, serological evidence for foot-and-mouth disease (FMD) infection was found as a result of differential diagnostic testing of Cypriot sheep suspected to be infected with bluetongue or contagious ecthyma. Seropositive sheep and goats were subsequently uncovered on ten geographically clustered flocks, while cattle and pigs in neighbouring herds were all seronegative. These antibodies were specific for serotype-O FMD virus, reacting with both structural and non-structural (NS) FMD viral proteins. However, no FMD virus could be recovered from the seropositive flocks. FMD had not been recorded in Cyprus since 1964 and there has been no vaccination programme since 1984. Since all the seropositive animals were at least 3 years old and home-bred, it was concluded that infection had occurred approximately 3 years previously had passed un-noticed and died out spontaneously. It therefore appears that antibodies to FMD virus NS proteins can still be detected around 3 years after infection of small ruminants, but that virus carriers cannot be detected at this time. This unusual situation of finding evidence of historical infection in a FMD-free country caused considerable disruption and alarm and posed questions about the definition of what constitutes a FMD outbreak.