A survey for antibodies against current infection of foot-and-mouth disease virus in Sudanese cattle, sheep and goats using neutralization test
AbstractA screening format of serum neutralization (SN) test was used to screen Sudanese cattle, sheep and goats sera against current infection of type "O" and "SAT2" foot-and-mouth disease (FMD) viruses. The format
was easy to perform; reading of results was objective and it detected high seropositivity in distinct test groups of cattle; as high as 82.6% and 43.7% for types "O" and "SAT2" respectively. Similar figures to these have been
reported using the sensitive liquid-phase blocking ELISA (LPBE) in recent different occasions. Results obtained by the screening format confirmed recent serological findings obtained by the LPBE. Serotype specific antibodies against types "O" and "SAT2" were significantly higher in tested cattle (63.15% and 20.63% respectively) than in tested sheep (9.16% and 1.16% respectively). None of the examined goats proved to be positive to either serotypes (n= 35 and 27 respectively). Seroprevalence of antibodies to the long known predominant type "O", unlike seroprevalence of type "SAT2" antibodies, was markedly lower in local (33.3%) than in cross (63.15%) tested cattle breeds. In Western Sudan, where local breeds of cattle prevail, seroprevalence of antibody to the moderately prevalent type "SAT2" (40%) even surpassed that of antibody to type "O" (25%).
It could be concluded that unapparent FMD infection in sheep and goats in Sudan occurs secondary to infection in cattle and no separate cycle of FMD infection occurs in these species. The results were highly suggestive of a diminished role of sheep and goats in the epidemiology of FMD within the epidemiological setup of Sudan. Likewise, results were suggestive of development of natural resistance in local cattle breeds to the earliest country reported type "O" infection.