A study on the seroprevalence of brucellosis in sheep in Naushahro Feroze, Sindh

During present survey, 160 sheep of both sexes and different ages were examined using Rose Bengal Plate Test (RBPT), Serum Agglutination Test (SAT) and Milk Ring Test (MRT). The overall seroprevelance of brucellosis was recorded to be 4.37%, 3.12% and 10.00% by RBPT, SAT and MRT respectively. In this survey, 80 male and similar number of females sheep were examined by RBPT and SAT techniques. 40 milk samples from female sheep were also examined by MRT. The prevalence of brucellosis in females was recorded as 5.00, 3.75 and 10.00% by RBPT, SAT and MRT respectively, while in males, it was observed as 3.75% and 2.50% by RBPT and SAT respectively. During present study, 80 adult male sheep (above 12 month) were examined by RBPT, SAT and 40 adult female sheep by MRT while, 80 young sheep (up to 9 month) by RBPT and SAT. The positive cases of brucellosis in adult sheep were recorded as 7.50%, 5.00% and 10.00% by RBPT, SAT and MRT respectively. While in young sheep, it was recorded as 2.50% and 1.25% by RBPT and SAT. A total of 40 adult female sheep were investigated, through Rose Bengal Plate, Serum Agglutination and Milk Ring Tests which detected 7.50, 5.00 and 10.00% brucellosis in adult female sheep respectively. Similarly, the same number of young female sheep were examined by Rose Bengal Plate and Serum Agglutination Tests, the result was recorded as 2.50% and 2.50% respectively, while remaining were considered to be negative or free from any brucellosis. Furthermore, 40 adult male sheep and similar number of young male sheep were examined by RBP and SA methods, the seroprevalence of brucellosis was recorded as 5.00% by each RBPT and SAT in adult male sheep. However, in young male sheep, it was found to be 2.50% by RBPT, whereas no any single young male sheep was found to be positive for brucellosis by SA technique. The serum samples of 40 adult female sheep were titrated, 2 sera from 40 adult female sheep were show n positive interaction at serum dilution 1:80, while no any positive interaction was found beyond the above dilution. Similarly, 40 serum samples from young female sheep were also titrated, 1 serum sample was detected to be positive at serum antibody titer 1:40. On other hand, a total of 40 adult male and similar number of young male sheep sera were tested by Tube Agglutination Test (SAT), 2 positive samples were detected. From these 2 positive cases, only 1 serum sample interacted and showed 1:40 serum antibody titer whereas 1 serum sample from adult male showed antibody titer which was recorded as 1:80. However, no any interaction between antigen and serum antibodies was found beyond this titer. Further that no any positive interaction between antigen antibody was found at any serum antibody dilution in the sera of young male sheep. Brucella abortus antigen interacted with 6 serum samples contained the antibodies of Brucella abortus species while with simple modification in the procedure where two drops of sera were added to antigen showed the characteristics of melitensis and recorded as positive for melitensis. During present study, 7 sera showed the presence of melitensis antibodies. Serologically, the incidence of Brucella 59 abortus and melitensis was recorded as 3.75 and 3.75% by RBPT, whereas 2.50 and 3.13% by SAT in the sera of sheep, respectively. It is concluded that the brucellosis is prevailing in the area. It was relatively higher in females as compared to males. Further that higher prevalence of brucellosis was present in adult females than in males. However, serologically young females were found more susceptible to brucellosis than young males. Overall serological study showed that the incidence of brucellosis was higher compared to young of both sexes of sheep. The higher was recorded as compared to Brucella abortus (3.75%) in sheep. The serum antibody titers of Brucella abortus and melitensis were also determined which interac ted with antigen at serum dilutions of 1:40 and 1:80 however, beyond these dilutions no interactions between antigen and serum antibody were observed. It was also concluded that the Serum Agglutination Test (SAT) technique is highly specific, sensitive and relatively more accurate in determining brucellosis in animals as compared to Rose Bengal Plate Test (RBPT) and Milk Ring Test (MRT) which some times produced false results.