Isolation of Digital Dermatitis Treponemes from Hoof Lesions in Wild North American Elk (Cervus elaphus) in Washington State, USA

Abstract

c Since 2008, a large increase in the numbers of cases of lameness have been seen in wild North American elk (Cervus elaphus) from Washington State, USA. The most recent cases manifested as foot lesions similar both clinically and pathologically to those seen in digital dermatitis (DD) in cattle and sheep, a disease with a bacterial etiopathogenesis. To determine whether the same bacteria considered responsible for DD are associated with elk lameness, lesion samples were subjected to bacterial isolation studies and PCR assays for three phylogroups of relevant DD treponemes. The DD treponemes were isolated from lesional tissues but not from control feet or other areas of the diseased foot (including the coronary band or interdigital space), suggesting that the bacteria are strongly associated with DD lesions and may therefore be causal. In addition, PCR analysis revealed that all three unique DD treponeme phylotypes were found in elk hoof disease, and in 23% of samples, all 3 DD-associated treponemes were present in lesions. Sequence analysis of the 16S rRNA gene showed that the elk lesion treponemes were phylogenetically almost identical to those isolated from cattle and sheep DD lesions. The isolates were particularly similar to two of the three culturable DD treponeme phylotypes: specifically, the Treponema medium/Treponema vincentii-like and Treponema phagedenislike DD spirochetes. The third treponeme culturable phylogroup (Treponema pedis), although detected by PCR, was not isolated. This is the first report describing isolation of DD treponemes from a wildlife host, suggesting that the disease may be evolving to include a wider spectrum of cloven-hoofed animals.

High-Level Association of Bovine Digital Dermatitis Treponema spp. with Contagious Ovine Digital Dermatitis Lesions and Presence of Fusobacterium necrophorum and Dichelobacter nodosus

“…This strong phylogenetic relationship further strengthens the case for CODD and BDD having a shared treponemal etiopathogenesis. Interestingly, epidemiological data demonstrate an association between the presence of CODD in sheep with cattle on farms (55), and the study areas that allowed for identification of a CODD-like manifestation in U.S. elk were cograzed by cattle and sheep (22). Taken together, these observations suggest this disease is managing to transmit between host species effectively on shared farmland.…”

“…Now, CODD has spread into the Republic of Ireland (20), and it was recently reported in dairy goats in the United Kingdom (21), indicating further cross-species transmission. The contagious nature of DD is also evident by the reports of a manifestation of the disease in a wildlife host, North American elk (Cervus elaphus) from Washington State (22). The reports of DD in previously unaffected species, including U.S. wildlife, suggests a much greater global threat of the disease than previously considered.…”

“…As a result of the severity of the lesions, sheep can be extremely lame, impacting the welfare of the affected sheep (28). This is concurrent with the lesion pathology identified in elk, described as erosive lesions on the coronary band which lead to underrunning of the hoof wall (22,29).…”

“…With the emergence of CODD in dairy goats in the United Kingdom (21) and foot disease in elk in the United States recently reported as both clinically and etiologically similar (22), CODD is clearly increasing in importance and geographical spread. It is very clear that CODD leads to severe animal welfare issues for the animal involved and leads to significant financial implications for farmers (54) and hence is a food security issue.…”

“…putidum-like" BDD spirochetes (34) with the latter now recognized as a new species, Treponema pedis (36). These three phylogroups of Treponema have also been reported in DD lesions in beef cattle (4) and also in DD lesions in goats (21) and elk (22). Due to the promiscuous nature of these treponemes and their growing host range, it is necessary to gain more information on their etiological role in currently infected species.…”