Preliminary seromonitoring of rinderpest among cattle raised under different husbandry systems in Saudi Arabia.

Using the competitive enzyme-linked immunosorbent assay for the seromonitoring of rinderpest in Saudi Arabia, antibodies were detected in 30% of the sera of 1,018 cattle slaughtered at Riyadh abattoir during June and July 1995. The correlation between the detection of antibodies and the origins of the slaughtered animals was analysed. All the culled dairy cows had detectable antibodies. The proportions of bulls giving serologically positive results were as follows: 57% for animals imported from rinderpest-free countries and vaccinated upon arrival in Saudi quarantine, 20% for native breeding animals and 17% for five- to ten-month-old bull calves born on commercial dairy farms and then raised on separate feedlot farms. In addition, of 105 native cattle sacrificed during the Hajj season in May 1994, 77% had antibodies against rinderpest virus. On the other hand, testing of 17 groups of dairy heifers (from 1 week to 24 months of age), born to immune dams and vaccinated against rinderpest at the ages of six and ten months, revealed the absence of detectable antibodies in the sera of some animals which were between two and ten months of age. Results are interpreted in relation to evaluation of the continuing vaccination programmes and their efficacy as an element of the national programme for the control of rinderpest.