Serological survey of foot and mouth disease in Saudi Arabia.

An immunodiffusion test using foot and mouth disease (FMD) virus infection-associated (VIA) antigen was used to detect precipitating antibodies in serum samples collected from non-vaccinated indigenous ruminants raised in different regions of Saudi Arabia. Of 5,985 sheep sera, 1,371 goat sera, 1,052 cattle sera and 694 serum samples from unspecified species of ruminants, precipitating activity was detected in 1,209 (20%), 127 (9%), 172 (16%) and 38 (5%) samples, respectively. In addition, 100 sera showing precipitating activity against VIA antigen originating from 13 different regions were tested for the presence of naturally-occurring neutralising antibodies against the four serotypes of FMD virus (O, A, Asia 1, and C) currently prevalent in the region and incorporated in the vaccine being used. All sera tested gave varying titres against serotypes O, A and/or Asia 1. However, none of the sera showed neutralising activities against serotype C. The results obtained are interpreted with regard to the geographical distribution and epizootiology of FMD in Saudi Arabia.