Comparative study of the commonly used virulence tests for laboratory diagnosis of ovine footrot caused by Dichelobacter nodosus in Australia.
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Open Access
Type
ArticleAbstract
Footrot in sheep and goats is expressed as a spectrum of clinical entities ranging from benign, which is a self limiting interdigital dermatitis to highly virulent, in which severe under running of the horn of the hoof occurs. Interactions between the host, the virulence of the ...
See moreFootrot in sheep and goats is expressed as a spectrum of clinical entities ranging from benign, which is a self limiting interdigital dermatitis to highly virulent, in which severe under running of the horn of the hoof occurs. Interactions between the host, the virulence of the causative strain of Dichelobacter nodosus and environmental conditions determine the severity of the disease. Clinical diagnosis of virulent footrot, which a notifiable disease in some states of Australia, is not always straightforward. Therefore, the Gelatin Gel and Elastase tests for protease activity, and the intA PCR test for an inserted genetic element in D. nodosus are commonly used to support or to confirm a clinical diagnosis. A comparative study of these laboratory tests with a large number of samples collected from 12 flocks of sheep with clinically virulent footrot was conducted. Based on the elastase test, 64% of the isolates tested were classified as virulent compared to 91% on the gelatin gel test and 41% according to the intA test. The agreement between the elastase and the gelatin gel test was low (kappa =0.12) as were the agreements between other tests. Only about 21% of the isolates were virulent in all 3 tests. Therefore these tests on their own may not provide standard and reliable results and are likely to remain as supplementary tests for clinical diagnosis of the disease. Keywords: Footrot, virulence, elastase test, gelatin gel test, intA PCR test.
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See moreFootrot in sheep and goats is expressed as a spectrum of clinical entities ranging from benign, which is a self limiting interdigital dermatitis to highly virulent, in which severe under running of the horn of the hoof occurs. Interactions between the host, the virulence of the causative strain of Dichelobacter nodosus and environmental conditions determine the severity of the disease. Clinical diagnosis of virulent footrot, which a notifiable disease in some states of Australia, is not always straightforward. Therefore, the Gelatin Gel and Elastase tests for protease activity, and the intA PCR test for an inserted genetic element in D. nodosus are commonly used to support or to confirm a clinical diagnosis. A comparative study of these laboratory tests with a large number of samples collected from 12 flocks of sheep with clinically virulent footrot was conducted. Based on the elastase test, 64% of the isolates tested were classified as virulent compared to 91% on the gelatin gel test and 41% according to the intA test. The agreement between the elastase and the gelatin gel test was low (kappa =0.12) as were the agreements between other tests. Only about 21% of the isolates were virulent in all 3 tests. Therefore these tests on their own may not provide standard and reliable results and are likely to remain as supplementary tests for clinical diagnosis of the disease. Keywords: Footrot, virulence, elastase test, gelatin gel test, intA PCR test.
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Date
2013-01-01Publisher
ElsevierDepartment, Discipline or Centre
Veterinary ScienceCitation
Dhungyel, O. P., Hill, A. E., Dhand, N. K., & Whittington, R. J. (2013). Comparative study of the commonly used virulence tests for laboratory diagnosis of ovine footrot caused by Dichelobacter nodosus in Australia. Vet Microbiol, 162(2-4), 756-760. Available online at http://www.sciencedirect.com/science/article/pii/S037811351200538XShare