Detection of Treponema species associated with bovine digital dermatitis in cattle using novel real-time PCR assays.

Abstract

Three Treponema sp.-T. medium, T. pedis, and T. phagedenis-are associated with bovine digital dermatitis (BDD). This painful infectious disease has been reported worldwide, causing economic and animal welfare problems. Although detection by real-time PCR (rtPCR) is the method of choice, published assays differ in specificity and sensitivity. We multiplexed target regions of 2 published rtPCR assays and slightly optimized another one to compare their performance. We then used the 2 novel TaqMan rtPCR assays to determine the prevalence of the 3 Treponema sp. in a random sample of hind feet from 137 animals collected at slaughterhouses. An overall prevalence at the animal level of 31.4% was found for T. phagedenis and 10.2% for T. medium, with the latter always being detected together with T. phagedenis. We did not detect T. pedis in our sample set. Typical lesions of BDD were present in 16.2% of animals. Of the animals with BDD lesions, 52.6% were positive for any of the 3 Treponema sp. A significantly lower positive rate for Treponema sp. was found in animals without lesions, underscoring the role of these organisms in the development of BDD. Our study offers insight into the prevalence of BDD-associated Treponema sp. in cattle as well as a tool for routine diagnosis and future control of the disease.