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Clinical and Vaccine Immunology, October 2007, p. 1356-1361, Vol. 14, No. 10
1071-412X/07/$08.00+0     doi:10.1128/CVI.00205-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

High Prevalence and Increased Severity of Pathology of Bovine Tuberculosis in Holsteins Compared to Zebu Breeds under Field Cattle Husbandry in Central Ethiopia

Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia,¹ Armauer Hansen Research Institute, P.O. Box 1005, Addis Ababa, Ethiopia,² Department of Infectious Disease and Microbiology, Imperial College, South Kensington Campus, London, SW7 2AZ, United Kingdom,³ TB Research Group, Veterinary Laboratories Agency, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom⁴

Received 20 May 2007/ Returned for modification 29 June 2007/ Accepted 19 August 2007

A comparative study on the prevalence and pathology of bovine tuberculosis (TB) was conducted on 5,424 cattle (2,578 zebus, 1,921 crosses, and 925 Holsteins), which were kept on pasture in the central highlands of Ethiopia, using a comparative intradermal tuberculin test, postmortem examination, and bacteriology. The overall prevalence of bovine TB was 13.5%; prevalence was higher in Holsteins than either zebus (22.2% versus 11.6%, ² = 61.8; P < 0.001) or crosses (22.2% versus 11.9%, ² = 50.7; P < 0.001). Moreover, the severity of pathology in Holsteins (mean ± standard error of the mean [SEM], 6.84 ± 0.79) was significantly higher (P = 0.018) than the severity of pathology in zebus (5.21 ± 0.30). In addition, the risk of TB in Holsteins was more than twice (odds ratio [OR] = 2.32; 95% confidence interval [CI] = 1.89, 2.85) that in zebus. Animals between 5 and 9 years of age were at higher (OR = 2.37; 95% CI = 1.80, 3.12) risk of bovine TB than those 2 years of age or below. A significant difference (² = 351; P < 0.001) in the occurrence of TB lesions in lymph nodes was recorded; the mesenteric lymph node (mean pathology score ± SEM, 1.95 ± 0.08) was most severely affected, followed by the retropharyngeal (0.80 ± 0.05) and caudal mediastinal (0.8 ± 0.06) lymph nodes. Fifty-six percent (n = 145) of the animals with gross TB lesions were culture positive; the lowest culture positivity was recorded in the skin lesions (27.3%) and the lesions of the mesenteric lymph node (31.5%). Both the skin test response and the postmortem findings suggested a higher susceptibility to bovine TB in Holsteins than zebus under identical field husbandry conditions (on pasture). In the light of increased numbers of Holstein cattle introduced into this area to raise milk production to satisfy the needs of Addis Ababa's growing population, these findings highlight the need for a control program in these herds.

Published ahead of print on 29 August 2007.

This article has been cited by other articles:

• Ameni, G., Hewinson, G., Aseffa, A., Young, D., Vordermeier, M. (2008). Appraisal of Interpretation Criteria for the Comparative Intradermal Tuberculin Test for Diagnosis of Tuberculosis in Cattle in Central Ethiopia. CVI 15: 1272-1276 [Abstract] [Full Text]