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.

The serologic prevalence of Q fever (Coxiella burnetii) complement-fixing antibodies in the Peninsular bighorn sheep of Southern California.

Q fever is a rare illness in the Southern California desert. During the past 34 years only 6 patients have been diagnosed with the disease at the Eisenhower Medical Center, a referral center for much of the desert and surrounding mountains. In all but 2 instances, Q fever was identified in patients who have been in contact with imported domestic sheep who are brought to the desert to graze and lamb in the fall and winter. The sheep are sent back to Idaho, Wyoming, and Montana in the spring. With frequent infection by Coxiella burnetii established in domestic sheep, we elected to study the prevalence of complement fixing antibodies to Coxiella burnetii in native bighorn sheep who reside in the lower levels of the mountains surrounding the desert. From 1992 to 1999, of 268 serum samples drawn from male and female lambs and adult sheep, 27 tested positive (10%), which is strikingly low when compared with Dall sheep in Alaska (12 of 15), kangaroos, wild rabbits, and brown rats. Because changes have been made in Peninsular bighorn sheep habitat since the animals were listed as endangered in 1998, further follow-up in Q fever serology testing will be of interest.

Q fever in the Southern California desert: epidemiology, clinical presentation and treatment.

Despite the absence of a natural reservoir for Q fever in the desert of Southern California, six cases have been identified during the past 32 years. During that period of time, two areas have been used by northern sheep ranchers from Idaho and Wyoming to import sheep to an area in the Coachella Valley through 1985. Thereafter, because of housing development, the sheep area was moved to Blythe along the Colorado River. All but two of these patients probably acquired infection by Coxiella burnetii by living or working in close proximity to these grazing areas but not directly involved with the sheep. The shift of infected patients from the Coachella Valley to Blythe (100 miles distant) seems to support that supposition. All patients with acute Q fever developed antibodies primarily to phase II antigen, whereas the only person with chronic Q fever developed phase I antibodies. All patients presented with granulomatous hepatitis. One also had a pulmonary infiltrate, and the single individual with chronic Q fever also had a mitral valve prosthesis, although echocardiography could not define endocarditis. All patients with acute infections responded to 3-5 weeks of therapy with doxycycline, whereas the patient with chronic disease failed 3 years of therapy with combination regimens. Further studies at the Eisenhower Medical Center on the prevalence of infection in Blythe, CA, and elsewhere are anticipated.