Serosurveillance for Livestock Pathogens in Free-Ranging Mule Deer (Odocoileus hemionus)

Abstract

Routine disease surveillance has been conducted for decades in mule deer (Odocoileus hemionus) in California for pathogens shared between wildlife and domestic ruminants that may have implications for the animal production industry and wildlife health. Deer sampled from 1990 to 2007 (n = 2,619) were tested for exposure to six pathogens: bluetongue virus (BTV), epizootic hemorrhagic disease virus (EHDV), bovine viral diarrhea virus (BVDV), Leptospira spp., Anaplasma spp. and Brucella spp. We evaluated the relationship between exposure to these pathogens and demographic risk factors to identify broad patterns in seroprevalence across a large temporal and spatial scale. The overall seroprevalence for the entire study period was 13.4% for BTV, 16.8% for EHDV, 17.1% for BVDV, 6.5% for Leptospira spp., 0.2% for Brucella spp., and 17% for Anaplasma spp. Antibodies against BTV and EHDV were most prevalent in the deer populations of southern California. Antibodies against Leptospira spp. and Anaplasma spp. were most prevalent in coastal and central northern California whereas antibodies against BVDV were most prevalent in central-eastern and northeastern California. The overall seroprevalence for Anaplasma spp. was slightly lower than detected in previous studies. North and central eastern California contains large tracts of federal land grazed by livestock; therefore, possible contact between deer and livestock could explain the high BVDV seroprevalence found in these areas. Findings from this study will help to establish baseline values for future comparisons of pathogen exposure in deer, inform on long-term trends in deer population health and provide relevant information on the distribution of diseases that are shared between wildlife and livestock.

Bluetongue Virus in wild ruminants in Europe: Concerns and facts, with a brief reference to bluetongue in cervids in Greece during the 2014 outbreak

“…Experimental infection in wild sheep, antelopes, American bisons and African buffaloes have led to various clinical manifestations and, occasionally, in fatal disease (Barzilai and Tadmor, 1972;Tessaro and Clavijo, 2001;Ortega et al, 2010). In contrast, several cervids (white-tailed deer, mule deer, North American elk, European red deer) or camelids appear to mount an adequate immune response against the virus, which can lead to, mainly, subclinical infection or mild transient disease (Murray and Trainer, 1970;Thomas and Trainer, 1970;Howerth and Tyler, 1988;Howerth et al, 2001;Roug et al, 2012;Schulz et al, 2012).…”

A Deterministic Model to Quantify Risk and Guide Mitigation Strategies to Reduce Bluetongue Virus Transmission in California Dairy Cattle

“…sonorensis abundance patterns, which smooth the variation in these quantities. Within an individual season or on an individual farm, it is possible that R 0 values could be higher, either due to more favorable short-term conditions for transmission than we captured with long-term averages, stochasticity that is not represented by our deterministic model, or in some areas, unrecognized BTV-competent wild ruminants that could serve as a source for transmission to cattle [61, 62]. …”

Epizootic haemorrhagic disease

“…The high seroprevalence of EHDV infection among ruminants in endemic areas indicates that most ungulates survive infection with the virus and experience only subclinical infections (2,18,28,30,37,45,46,47,48,49,50,51). In Australia, for example, where six serotypes of EHDV have been recognised, and five of these for more than 30 years (54), clinical disease attributable to EHDV infection has not been recognised.…”

“…For instance, although serological surveys indicate that EHDV infection of wild and domestic ruminants is prevalent throughout western North America, such infections are invariably subclinical or asymptomatic, and it is an adenovirus, and not EHDV or bluetongue virus (BTV), that is the cause of the haemorrhagic disease syndrome that occurs commonly among black-tailed and mule deer (Odocoileus hemionus) in the region (L.W. Woods,personal communication;18,28,36).…”