Disseminated Bovine Tuberculosis in a Wild Red Fox (Vulpes vulpes) in Southern Spain

Abstract

A wild-caught, adult red fox (Vulpes vulpes) from Doñana National Park (southern Spain), in very poor condition, died during anesthesia. At necropsy, the submandibular, retropharyngeal, mediastinal, axillary, mesenteric, and popliteal lymph nodes were enlarged, and the right submandibular and mesenteric lymph nodes had hard, white-colored concretions (calcifications). Multiple white pinpoint foci were observed in the lungs, and abscesses were present in the left dorsal lung lobes. No lesions were seen in tonsils, liver, or spleen. On histopathology multiple tuberculous granulomas, with Ziehl-Neelsen-positive bacilli, were observed in the lung, and multifocal necrotic areas with calcification were present in the submandibular and mesenteric lymph nodes. Nucleic acid amplification from lymph node samples demonstrated the presence of mycobacteria belonging to the Mycobacterium tuberculosis complex. One strain was isolated by culture and identified as Mycobacterium bovis. The suspected route of infection was oral, probably after repeated scavenging of infected wild ungulate carcasses. This is the first report of generalized bovine tuberculosis (bTB) in a wild canid. This finding raises concerns about bTB as a disease risk for protected species, livestock, and humans in Mediterranean Spain.

Lack of evidence of paratuberculosis in wild canids from Southwestern Europe

“…Since canids only rarely develop lesions when they have a generalized M. bovis infection (Millan et al 2008), the lack of paratuberculosis and bTB-compatible lesions was not a surprising finding in this study. However, this lack of visible lesions in a large sample of wild canids, along with the absence of microscopic lesions in the studied subsample, adds to the view that wild canids play no relevant role in the epidemiology of mycobacterial diseases in Southwestern Europe.…”

Disseminated Mycobacterium bovis Infection in Red Foxes (Vulpes vulpes) with Cerebral Involvement Found in Portugal

“…The results suggest that M. bovis circulates widely in the studied area, which is a serious concern for wildlife. Our findings have also revealed a public health concern because veterinarians and other professional workers, as well as hunters who come into contact with these species, have a high risk of being infected when handling infected samples and tissues (Millán et al 2008).…”

“…The extent to which infected red foxes may be involved in the epidemiology of M. bovis in other wild mammals remains unknown. Foxes most probably become infected after scavenging of infected wild ungulate carcasses (Millán et al 2008), because bovine tuberculosis was previously reported in wild ungulates in the studied area (Santos, et al 2009). …”

“…The detection of MTC members has been previously reported in wild canids in reservoirs worldwide, such as in coyote (Canis latrans) (Rhyan et al 1995,VerCauteren et al 2008, wolf (Canis lupus) (Carbyn 1982), gray fox (Urocyon cinereoargenteus) (Bruning-Fann et al 2001), and red fox (Vulpes vulpes) (Delahay et al 2007, Martín-Atance et al 2005, Millán et al 2008.…”

“…These species exhibit similar genetic homology but differ considerably in their host range and pathogenicity; most of them are zoonotic agents (Palgrave et al 2012). There are few reports of MTC in foxes (Bruning-Fann et al 2001, Delahay et al 2007, Millán et al 2008. In animals, the infection caused by these agents has only been reported in the brain of rabbits, mice, and pigs in an experimental model infection (Hernandez Pando et al 2010).…”