A herd level analysis of a Corynebacterium pseudotuberculosis outbreak in a dairy cattle herd |
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| Authors: | Yeruham Israel Friedman Samuel Perl Samuel Elad Daniel Berkovich Yair Kalgard Yoram |
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| Institution: | 'Hachaklait' Gedera and the Koret School of Veterinary Medicine, the Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel. chkl1357@netvision.net.il |
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| Abstract: | Corynebacterium pseudotuberculosis infection in an Israeli dairy cattle herd is described. The disease was characterized by ulcerative granulomatous lesions, which occurred in an epidemic form. Thirty-two cows and two heifers were affected, the ratio of the number affected to number at risk being 17.5 : 1 and 9.5 : 1, respectively. The culling rate was 50% of the affected animals. Most of the affected animals were cows (91.2%), with one first-calving cow (2.9%) and two heifers (5.9%) also affected. The infection occurred during the summer to autumn months (August-December), and lasted 118 days. The incubation period is about 2 months. The disease appeared in two clinical forms - cutaneous and mastitic - or as a mixed form. C. pseudotuberculosis organisms that were isolated from the ulcerative granulomatous lesions and from milk samples failed to reduce nitrate. A decrease in milk production (4%) and an increase in the bulk-milk somatic cell count from a herd mean of 240 x 10(3) mL(-1) to 460 x 10(3) mL(-1) were noted during the morbidity period. The organism was isolated from milk samples of eight animals (25%). Clinical, epizootiological and microbiological aspects of the infection are described. |
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| Keywords: | Corynebacterium pseudotuberculosis dairy cattle ulcerative granulomatous lesions |
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