Seroprevalence and excretion status of Salmonella pullorum-gallinarum in chicken around Kampala Uganda

Abstract

A survey to establish the prevalence of Salmonella pullorum-gallinarum was undertaken during April – November 1997. The whole blood rapid agglutination (WBRA) test was employed to test for presence of antibodies to and the excretion status of Salmonella pullorum-gallinarum in chicken from farms around Kampala where most intensive poultry keeping is practiced. Serological testing was carried out on the farms while isolation was done in the laboratory at the Faculty of Veterinary Medicine, Makerere University. Out of the total 871 chickens tested, 104 were broilers, 273 were pullets and 494 were layers; 581 were vaccinated against fowl typhoid and 290 were from non-vaccinated flocks. Of the 871 chicken tested, 302 (34.7%) were positive by the WBRA test, of which 31 were broilers, 68 were pullets and 203 were layers. Some chicken, 263 (30.2%) gave doubtful reactions, of which 31 were broilers, 85 were pullets and 147 were layers. The seroprevalence varied from 18.3% in non-vaccinated flocks to 58.6% in the vaccinated ones. The average prevalence in non-vaccinated chicken was 27.9% and 37.9% in the vaccinated ones, and there were significant differences in the prevalence of seropositivity between the vaccinated and non-vaccinated chicken (χ2 p=8.55E-09) and the producer flocks versus the breeder flocks (χ2 p=0.025). Bacteriological isolation revealed an excretion status of 8% in the non-vaccinates and 2% in the vaccinates. The WBRA test can be utilized to detect and dispose of the positive reactors and even trace them to flocks and/or hatcheries of origin in order to control the sources of infection. Doubtful reactors should be re-tested after one to two weeks to ascertain their status. A combination of this test with other serological tests, such as ELISA, Rapid Serum Plate test, Tube Agglutination and Micro-agglutination, is useful in enhancing the control and eventual eradication of pullorum-typhoid infection. However, with increasing intensification of poultry production, with little or no Salmonellosis control measures in place, the prevalence is likely to increase.