Infectious keratoconjunctivitis in bighorn sheep, Silver Bell Mountains, Arizona, USA.

An infectious keratoconjunctivitis (IKC) epizootic in bighorn sheep (Ovis canadensis) occurred in the Silver Bell Mountains, Arizona, USA, from 1 December 2003 to 31 March 2004. We used standard culture methods and polymerase chain reaction (PCR) amplification of the 16S rRNA gene to test for the causative agents of IKC and other diseases reported to be associated with bighorn sheep populations. All bighorn sheep and domestic goat test results were negative except for Mycoplasma spp. and Branhamella spp. The culture and PCR results differed. Conjunctival swabs from four of 19 IKC-affected bighorn sheep tested by culture were positive for Mycoplasma spp., whereas 22 of 22 bighorn sheep samples tested by PCR were positive for Mycoplasma spp. None of 13 domestic goats tested positive by culture for Mycoplasma spp., whereas five of 16 tested positive by PCR. Three of 16 domestic goats and seven of 24 IKC-affected bighorn sheep tested positive for Branhamella spp. by culture. Bighorn sheep began showing clinical signs of IKC between 21 and 28 days following initial detection of domestic goats in bighorn sheep habitat. The IKC epizootic lasted 122 days, and individual bighorn sheep were blind for an average of 38.4 days. Given the clear potential for disease transmission to bighorn sheep, we recommend that land managers not allow the pasturing of domestic goats near occupied bighorn sheep habitat.

Determining prevalence of bluetongue and epizootic hemorrhagic disease viruses in mule deer in Arizona (USA) using whole blood dried on paper strips compared to serum analyses.

We investigated the feasibility of using whole blood dried on paper strips as a means to collect antibody prevalence data for the epizootic hemorrhagic disease viruses (EHDV) and bluetongue viruses (BTV) from hunter-harvested male mule deer (Odocoileus hemionus) in October 2002 from Arizona, USA. We compared antibody prevalence estimates in mule deer from paired paper strip and serum samples. Prevalence data obtained from elution of dried blood on paper strips proved to be consistent with results from serum in 94% of the samples tested. The paper strip method allows easy collection of blood from dead animals, with a smaller amount of blood being needed for analyses. Also, samples do not need to be refrigerated before analyses. We also used serum samples to determine hemorrhagic disease (HD) serotype exposure status of mule deer harvested from 4 distinct areas in Arizona. Antibodies to BTV and EHDV were identified in 3 of the 4 areas, with positive results to EHDV-1, EHDV-2, BTV-10, and BTV-11 being most common. Many animals did not have antibodies against the BTV serotypes. Exposure varied geographically and potentially with elevation. Hemorrhagic disease viruses commonly infect Arizona mule deer, except on the Kaibab Plateau in northern Arizona.

Serologic survey for pathogens potentially affecting pronghorn (Antilocapra americana) fawn recruitment in Arizona, USA.

During the 1990s, pronghorn (Antilocapra americana) populations declined in Arizona, USA. To investigate potential causes of decline, we collected blood samples from hunter-harvested male pronghorn from 2001 to 2003 on four Arizona sites. Sera were tested for antibody to parainfluenza virus type 3 (PI3), bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine respiratory syncytial virus, epizootic hemorrhagic disease virus (EHDV), bluetongue virus (BTV), and Chlamydia psittaci. Antibody against PI3 was found in 33% of the samples, whereas antibody against BTV/EHDV was found in 77%. Antibodies to other pathogens were found at low prevalence rates. Although pronghorn decline in Arizona is probably not directly related to disease, potential reproductive effects of BTV/EHDV and PI3 infection on pronghorn in Arizona merit further study.

Evidence of tick-borne organisms in mule deer (Odocoileus hemionus) from the western United States.

Free-ranging mule deer (MD; Odocoileus hemionus) from Arizona and California were tested for evidence of infection with several tick-borne pathogens, including species of Ehrlichia, Anaplasma, Babesia, and Borrelia. Of 125 mule deer tested from Arizona, 29 (23%) and 11 (9%) had antibodies reactive to E. chaffeensis and A. phagocytophilum by indirect immunofluorescent antibody testing, respectively; none of the six MD tested from California were seropositive. Using a commercial competitive ELISA kit, antibodies reactive to Anaplasma spp. were detected in 19 (15%) MD from Arizona and four of six (67%) MD from California. Polymerase chain reaction (PCR) testing for tick-borne pathogens was conducted on blood samples from 29 MD from Arizona and 11 MD from California. Twenty-two of 29 (75.9%) MD from Arizona had PCR evidence of infection with at least one tick-borne pathogen. We detected an Anaplasma sp. in 19 of 29 (65.5%) MD and a Babesia sp. in 10 of 29 (34%) MD. Sequencing of these amplicons indicated that the Anaplasma sp. was the same that had previously been detected in MD from California and the Babesia sp. was similar to one previously detected in a reindeer (Rangifer tarandus tarandus) from California. All of the California MD had evidence of infection with a tick-borne pathogen. Two different species of Anaplasma spp. were detected in MD from California, eight of of 11 MD were infected with an Anaplasma sp., and three of 11 MD were infected with A. ovis. This is the first report of a mule deer naturally infected with A. ovis. Ten of 11 MD from California were infected with a Babesia-like organism previously associated with human disease, and a single MD was PCR positive for Borrelia coriaceae, which has been associated with epizootic bovine abortion. Together, these data suggest that MD in northern Arizona and eastern California are exposed to several pathogens of human and veterinary importance.

Epizootiology of hemorrhagic disease in mule deer in central Arizona.

We report two male mule deer (Odocoileus hemionus) mortalities that occurred near Prescott, Arizona (USA) in September 2001. Necropsy lesions were compatible with those described for hemorrhagic disease (HD). Bluetongue (BTV) and epizootic hemorrhagic disease (EHDV) viral RNA were identified in tissues from one deer and EHDV viral RNA was identified in the other via reverse transcription-polymerase chain reaction (RT-PCR). Virus isolation attempts were unsuccessful in both cases. To determine geographic range and viral serotypes involved, we collected blood samples from healthy hunter-harvested male mule deer in three game management units near Prescott in October 2001. Forty-one blood samples were collected and antibodies against EHDV and/or BTV were found in 21/41 (51%) samples as determined by agar immunodiffusion. Serum neutralization test results suggest that multiple EHDV and BTV serotypes are present in Arizona.