Pathogen surveillance and epidemiology in endangered Peninsular bighorn sheep (Ovis canadensis nelsoni).

Peninsular bighorn sheep (Ovis canadensis nelsoni) are found exclusively in Southern California and Baja Mexico. They are federally endangered due to multiple threats, including introduced infectious disease. From 1981 - 2017, we conducted surveillance for 16 pathogens and estimated population sizes, adult survival, and lamb survival. We used mixed effects regression models to assess disease patterns at the individual and population levels. Pathogen infection/exposure prevalence varied both spatially and temporally. Our findings indicate that the primary predictor of individual pathogen infection/exposure was the region in which an animal was captured, implying that transmission is driven by local ecological or behavioral factors. Higher Mycoplasma ovipneumoniae seropositivity was associated with lower lamb survival, consistent with lambs having high rates of pneumonia-associated mortality, which may be slowing population recovery. There was no association between M. ovipneumoniae and adult survival. Adult survival was positively associated with population size and parainfluenza-3 virus seroprevalence in the same year, and orf virus seroprevalence in the previous year. Peninsular bighorn sheep are recovering from small population sizes in a habitat of environmental extremes, compounded by infectious disease. Our research can help inform future pathogen surveillance and population monitoring for the long-term conservation of this population.

Previously Unrecognized Exposure of Desert Bighorn Sheep (Ovis canadensis nelsoni) to Mycoplasma ovipneumoniae in the California Mojave Desert.

A 2013 outbreak of respiratory disease in bighorn sheep from California's Mojave Desert metapopulation caused high mortality in at least one population. Subsequent PCR and strain-typing indicate widespread infection of a single strain of Mycoplasma ovipneumoniae throughout this region. Serosurvey of archived samples showed that some populations have had antibodies to M. ovipneumoniae since at least 1986, although pre-2013 strain-type data are unavailable.

Evidence for transmission of the zoonotic apicomplexan parasite Babesia duncani by the tick Dermacentor albipictus.

Babesiosis is a potentially fatal tick-borne zoonotic disease caused by a species complex of blood parasites that can infect a variety of vertebrates, particularly dogs, cattle, and humans. In the United States, human babesiosis is caused by two distinct parasites, Babesia microti and Babesia duncani. The enzootic cycle of B. microti, endemic in the northeastern and upper midwestern regions, has been well characterised. In the western United States, however, the natural reservoir host and tick vector have not been identified for B. duncani, greatly impeding efforts to understand and manage this zoonotic disease. Two and a half decades after B. duncani was first described in a human patient in Washington State, USA, we provide evidence that the enzootic tick vector is the winter tick, Dermacentor albipictus, and the reservoir host is likely the mule deer, Odocoileus hemionus. The broad, overlapping ranges of these two species covers a large portion of far-western North America, and is consistent with confirmed cases of B. duncani in the far-western United States.

MOLECULAR SURVEILLANCE FOR BARTONELLA, BORRELIA, AND RICKETTSIA SPECIES IN TICKS FROM DESERT BIGHORN SHEEP ( OVIS CANADENSIS) AND MULE DEER ( ODOCOILEUS HEMIONUS) IN SOUTHERN CALIFORNIA, USA.

: Ticks (Acari: Ixodidae) were collected from 44 desert bighorn sheep ( Ovis canadensis) and 10 mule deer ( Odocoileus hemionus) in southern California, US during health inspections in 2015-16. Specimens were identified and screened by PCR analysis to determine the presence and prevalence of Bartonella, Borrelia, and Rickettsia species in ticks associated with these wild ruminants. None of the 60 Dermacentor hunteri and 15 Dermacentor albipictus ticks tested yielded positive PCR results. Additional tick specimens should be collected and tested to determine the prevalence of these confirmed or suspected tickborne pathogens within ruminant populations.