Molecular Isolation of Treponema spp from Ovine Footrot Lesions, Finding Evidence for Contagious Ovine Digital Dermatitis

Abstract

Contagious ovine digital dermatitis (CODD), a severe lameness-causing bacterial foot disease, significantly impacts the sheep industry's economy and welfare. Treponema species responsible for bovine digital dermatitis (BDD), including Treponema medium, Treponema phagedenis, and Treponema pedis, have been identified in CODD lesions. In this study, Treponema spp. was detected in 42 skin samples from 110 sheep that had footrot lesions (38%). The lesions were more presented on hindlimbs (55.5%). The Kurdish sheep breed exhibited the highest Treponema positivity rate with 47.8% (n = 20), while pure Afshari sheep and Afshari-Kurdish hybrids showed an equal prevalence of 26.2%. The prevalence of lesion scores 4 and 5 in the Treponema-positive group (33.3% and 40.5% respectively) was significantly higher compared to the Treponema-negative group (23.5% and 11.8% respectively) further underscores the potential role of Treponema infection in the progression of severity of the infection. The southern region of the Khorasan Razavi province exhibited a significantly higher prevalence of Treponema-positive cases (88.1%, n = 37) compared to the northern regions (7.1%, n = 3) and Mashhad (4.8%, n = 2). This is the first report of investigation of the possible presence of CODD in Iranian sheep flocks, which should be potentially considered to prevent negative impacts on sheep production, welfare, and antibiotic use (improper antibiotic usage) in the farms.

Keywords

• contagious ovine digital dermatitis
• sheep
• footrot
• treponema