Bovine brucellosis among two different cattle populations in Bahr el Ghazal Province of Southern Sudan.

During a serological Brucella survey in Bahr el Ghazal Province (Southern Sudan), 6.5% of a total of 5982 randomly selected cattle of the Dinka tribe from 303 herds investigated showed positive results. Herds of bigger size were found to be more frequently infected than smaller herds. From 1228 randomly selected cattle of the Fellata tribe (Red Bororo race), 22.5% produced a positive reaction. Here, reactors were detected in 71 from a total of 72 herds tested (98.5%). Among the Dinka cattle, the number of reactors rose steadily in correspondence to the age of the animals. A somewhat more pronounced increase of reactors was observed in animals 4-8 years of age. On the other hand, the number of reactors in the Fellata herds increased rapidly between the age of 2-4 years. Thereafter, this infection rate did not change significantly any more. The results indicated that a significant portion (37.1%) of reactors graded positive (n = 665) expressed only low titers (less than or equal to 1:40) in the SAST. Those titers were even more numerous (49.1%) among the positive reactors belonging to cattle below the age of 4 years.