Molecular epidemiology of Salmonella gallinarum in chickens in Tanzania
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Date
2010-06-17
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Abstract
A molecular epidemiological investigation of Salmonella gallinarum infection in scavenging local
chickens and commercial layers in Tanzania was conducted between August 1997 and April 1998. A
total of 1152 chickens were randomly selected from 10 villages and seven commercial farms. For
serological and cultural prevalence studies, 1152 blood samples and 912 cloacal swabs were collected.
In scavenging local chickens, the individual serological and cultural prevalences were 6.3 and 0%,
while the prevalences were significantly higher in commercial layers at 18.4 and 2.6% (P < 0.001),
respectively. The risk of infection in flocks of scavenging local chickens that had contact with
commercial chickens was six times greater than the risk of infection in flocks of scavenging local
chickens that had no contact with commercial chickens. Thirty-four S. gallinarum isolated from
commercial chickens in this study, together with 29 Tanzanian historical isolates, were characterized
using plasmid profiling and ribotyping. Fifty-one isolates contained both 85 and 2.5 kb plasmids, five
isolates contained only one plasmid of 85 kb, and seven isolates had no plasmids. Ribotyping using
HindIII restriction endonuclease demonstrated seven different ribotypes. Forty-seven isolates had
similar results in both typing systems, suggesting they belonged to one clone. It is concluded that S.
gallinarum infection in chickens in Tanzania is more prevalent in commercial layers than in scavenging
local chickens. One strain of S. gallinarum from chickens first isolated in a Dar es Salaam hatchery was
found to be common throughout the country.
Description
Avian Pathology, 2000; 29:457– 463
Keywords
Molecular epidemiology, Salmonella gallinarum, Chickens, Commercial layers, Local chickens
Citation
Robinson H. Mdegela , Mmeta G.S. Yongolo , Uswege M. Minga & John E. Olsen (2000) Molecular epidemiology of Salmonella gallinarum in chickens in Tanzania, Avian Pathology, 29:5, 457-463