Pamela K. Swift

SYSTEMIC ADENOVIRUS INFECTION ASSOCIATED WITH HIGH MORTALITY IN MULE DEER (ODOCOILEUS HEMIONUS) IN CALIFORNIA

Seventeen counties in northern California experienced epizootics of high mortality in the mule deer (Odocoileus hemionus) population during the latter half of 1993. Thirteen deer submitted to the California Veterinary Diagnostic Laboratory System as part of this natural die-off had systemic adenovirus infection. Pulmonary edema was present in all 13 deer. Erosions, ulceration, and abscessation of the upper alimentary tract occurred in 7/13 deer. Four of 13 deer had hemorrhagic enteritis. All 13 deer had widespread systemic vasculitis with endothelial intranuclear inclusions. Fluorescein isothiocyanate-labeled antibody directed against bovine adenovirus type 5 bound to antigen in endothelial cells. Adenovirus was identified by transmission electron microscopy within the nuclei of endothelial cells in 6/6 deer examined. An adenovirus was isolated from lung homogenates of one deer that were cultured on black-tailed deer pulmonary artery endothelial cells. With the exception of the intranuclear inclusions evident on histologic evaluation, gross and histologic changes were similar to those described for bluetongue virus infection and epizootic hemorrhagic disease virus infection in white-tailed deer. Nine additional deer were emaciated and had pharyngeal abscesses with focal vasculitis, which may represent the chronic affects of previous nonfatal adenovirus infection.

GRANULOCYTIC EHRLICHIOSIS AND TICK INFESTATION IN MOUNTAIN LIONS IN CALIFORNIA

Forty-seven mountain lions (Puma concolor) collected year-round in 1996 to 1998 from the Sierra Nevada foothills, the northern coast ranges, and in Monterey County (California, USA) were examined for infestation with Ixodes pacificus and Dermacentor variabilis ticks. Ticks were found predominantly in winter and spring. The seroprevalence of granulocytic ehrlichiae (GE) antibodies (Ehrlichia equi or the agent of human granulocytic ehrlichiosis) was 17% and the PCR-prevalence of DNA characteristic of GE in blood was 16%. There were eight polymerase chain reaction (PCR)-positive but seronegative mountain lions, one that was PCR-positive and seropositive, and eight that were PCR-negative and seropositive. Nineteen percent of engorged tick pools from mountain lions were PCR-positive. Because mountain lions inhabit tick-infested habitat and are frequently bitten by I. pacificus, surveillance for GE antibodies and DNA in mountain lions and other vertebrate hosts may be useful as indicators for geographical regions in which humans are at risk of GE infection.

Neck lesions in ungulates from collars incorporating satellite technology

Wildlife Society Bulletin 2004, 32(3):987–991 Peer edited Investigators have used marking collars and telemetry collars to enhance knowledge about movements of ungulates for many decades. Technological advances have provided increasingly dependable and sophisticated equipment (Fancy et al. 1988; Mourao and Merdi 2002), and methods of collar attachment have evolved substantially, particularly with respect to juvenile ungulates (Smith et al. 1998, Bleich and Pierce 1999). Nevertheless, recent observations of mule deer (Odocoileus hemionus) and mountain sheep (Ovis canadensis) fitted with telemetry collars that incorporate Global Positioning Systems (GPS) and other satellite technology indicate those collars may cause injury to the study animal. The intent of investigators should be to minimize injuries and effects of marking on the behavior of animals (White and Garrott 1990), but our observations suggest lack of compliance in some cases with existing guidelines (Committee on Acceptable Field Methods 1987, Institutional Animal Use and Care Committee [Powell and Proulx 2003]). We placed collars incorporating GPS receivers and very high frequency (VHF) transmitters (Telonics, Mesa, Ariz.; and Posrec, TVP Positioning AB, Lindesberg, Sweden) on mule deer and mountain sheep. We collared female deer in Round Valley, Inyo, and Mono counties, California during March (n=12) and November 2002 (n=1). Four of 6 deer recaptured in November 2002, 2 of 3 recaptured in January 2003, and 2 of 2 recaptured in March 2003 (1 of which was collared in November 2002) exhibited all stages of ulcer formation except bone involvement. Patchy alopecia, nonblanchable erythema, induration, and edema of the intact skin surrounding ulceration were present. In some deer there was only partial skin loss and the ulcers were superficial; others revealed skin loss to the subcutaneous layer resembling a deep abrasion. The most severely affected deer had skin loss with extensive destruction of muscle on the dorsal aspect of the neck (Figure 1). Affected areas varied from 4–100 cm2 and extended from 4–8 cm distal of the occiput or jaw to the mid-cervical region on the dorsal and ventral surfaces of the neck, respectively; lateral surfaces were not involved. We removed collars from the 6 deer that exhibited lesions in November 2002 and January 2003. Three of those animals were recaptured in March 2003, and all lesions had healed completely. As part of long-term ecological investigations (Pierce et al. 2000a,b), we placed VHF collars from 3 manufacturers on 113 juvenile ( 500 adult mule deer of both sexes since 1992. We From the Field: Neck lesions in ungulates from collars incorporating satellite technology

Lesions and Transmission of Experimental Adenovirus Hemorrhagic Disease in Black-tailed Deer Fawns

Adenovirus infection was the cause of an epizootic of hemorrhagic disease that is believed to have killed thousands of mule deer (Odocoileus hemionus) in California during the latter half of 1993. A systemic vasculitis with pulmonary edema and hemorrhagic enteropathy or a localized vasculitis associated with necrotizing stomatitis/pharyngitis/glossitis or osteomyelitis of the jaw were common necropsy findings in animals that died during this epizootic. To study transmission of adenovirus infection in deer and susceptibility of black-tailed deer (Odocoileus hemionus columbianus) fawns to adenovirus infection, six 3–6-month-old black-tailed fawns were divided into two treatment groups. One group was inoculated intravenously and the other group was inoculated through the mucous membranes of the eyes, nose and mouth with purified adenovirus. Each treatment group also included two additional fawns (four total) that were not inoculated but were exposed to inoculated animals (contact animals). One fawn served as a negative control. Between 4 and 16 days postinoculation, 8/10 fawns developed systemic or localized infection with lesions identical to lesions seen in animals with natural disease that died during the epizootic. Transmission was by direct contact, and the route of inoculation did not affect the incubation period or the distribution of the virus (systemic or the localized infection). Immunohistochemical analysis using polyclonal antiserum against bovine adenovirus type 5 demonstrated staining in endothelial cells of vessels in numerous tissues in animals with systemic infection and endothelial staining only in vessels subtending necrotic foci in the upper alimentary tract in animals with the localized form of the disease. All inoculated or exposed animals had staining in the tonsillar epithelium. Transmission electron microscopic examination of lung and ileum from two fawns with pulmonary edema and hemorrhagic enteropathy demonstrated endothelial necrosis and adenovirus virions in endothelial cell nuclei. Adenovirus was reisolated in black-tailed deer pulmonary artery endothelial cells using lung homogenate of the first fawn that developed systemic adenovirus infection. Serum virus neutralization test results suggest that this deer adenovirus is a new serotype.

SALT TOXICOSIS IN RUDDY DUCKS THAT WINTER ON AN AGRICULTURAL EVAPORATION BASIN IN CALIFORNIA

Agricultural evaporation basins are used as a means to dispose of highly saline underground-tile-drainage water in the San Joaquin Valley (California, USA). The hypersaline water conditions encourage high aquatic invertebrate production, primarily brine shrimp (Artemia franciscana), which attract birds to these sites. Cool winter temperatures (<4 C) and hypersaline water conditions (>70,000 μmhos/cm) resulted in feather salt encrustation and salt toxicosis in ruddy ducks (Oxyura jamaicensis). During December 1998 and January 1999, approximately 200 dead and sick ruddy ducks were collected from an evaporation basin and five healthy control ruddy ducks were collected from a freshwater wetland. Brains contained ≥1,890 ppm sodium (wet tissue mass) in seven dead birds and contained ≤1,150 ppm sodium in the control birds. Liver arsenic, lead, and mercury concentrations were <1 ppm in all birds examined. Manganese, molybdenum, and copper liver concentrations did not differ significantly (P > 0.05) between the two groups of ducks. The dead ducks had significantly higher liver selenium, cadmium, iron, and zinc than the controls, but the concentrations were not sufficient to cause toxicity. Significant gross and microscopic lesions in most of the dead birds included conjunctivitis, lens opacity and cataract formation, vascular congestion in various organs most notably in the meninges of the brain, and myocardial and skeletal muscle degeneration.

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

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.

Desert Bighorn Sheep Mortality Due to Presumptive Type C Botulism in California

During a routine telemetry flight of the Mojave Desert (California, USA) in August 1995, mortality signals were detected from two of 12 radio-collared female desert bighorn sheep (Ovis canadensis) in the vicinity of Old Dad Peak in San Bernardino County (California). A series of field investigations determined that at least 45 bighorn sheep had died near two artificial water catchments (guzzlers), including 13 bighorn sheep which had presumably drowned in a guzzler tank. Samples from water contaminated by decomposing bighorn sheep carcasses and hemolyzed blood from a fresh bighorn sheep carcass were tested for the presence of pesticides, heavy metals, strychnine, blue-green algae, Clostridium botulinum toxin, ethylene glycol, nitrates, nitrites, sodium, and salts. Mouse bioassay and enzyme-linked immunosorbent assay detected type C botulinum toxin in the hemolyzed blood and in fly larvae and pupae. This, coupled with negative results from other analyses, led us to conclude that type C botulinum poisoning was most likely responsible for the mortality of bighorn sheep outside the guzzler tank.

EXPERIMENTAL ADENOVIRUS HEMORRHAGIC DISEASE IN YEARLING BLACK-TAILED DEER

An apparently novel adenovirus was associated with an epizootic of hemorrhagic disease that is believed to have killed thousands of mule deer (Odocoileus hemionus) in California (USA) during 1993—1994. A systemic vasculitis with pulmonary edema and hemorrhagic enteropathy or a localized vasculitis associated with necrotizing stomatitis/pharyngitis/glossitis or osteomyelitis of the jaw were common necropsy findings in animals that died during this epizootic. Six black-tailed yearling deer (O. hemionus columbianus) were inoculated with purified adenovirus isolated from a black-tailed fawn that died of acute adenovirus hemorrhagic disease during the epizootic. Three of six inoculated deer also received intramuscular injections of dexamethasone sodium phosphate every 3 days during the study. Eight days post-inoculation, one deer (without dexamethasone) developed bloody diarrhea and died. Necropsy and histopathologic findings were identical to lesions in free-ranging animals that died of the natural disease. Hemorrhagic enteropathy and pulmonary edema were the significant necropsy findings and there was microscopic vascular damage and endothelial intranuclear inclusion bodies in the vessels of the intestines and lungs. Adenovirus was identified in necrotic endothelial cells in the lungs by fluorescent antibody staining, immunohistochemistry and by transmission electron microscopy. Adenovirus was reisolated from tissues of the animal that died of experimental adenovirus hemorrhagic disease. Similar gross and microscopic lesions were absent in four of six adenovirus-inoculated deer and in the negative control animal which were necropsied at variable intervals during the 14 wk study. One deer was inoculated with purified adenovirus a second time, 12 wk after the first inoculation. Fifteen days after the second inoculation, this deer developed severe ulceration of the tongue, pharynx and rumen and necrotizing osteomyelitis of the mandible which was associated with vasculitis and thrombosis of adjacent large vessels and endothelial intranuclear inclusions. Transmission electron microscopy demonstrated adenovirus within the nuclei of vascular cells and immunohistochemistry demonstrated adenovirus antigen within tonsilar epithelium and in rare vessels.

RISK FACTORS FOR EXPOSURE TO FELINE PATHOGENS IN CALIFORNIA MOUNTAIN LIONS (PUMA CONCOLOR)

The primary challenge to mountain lion population viability in California is habitat loss and fragmentation. These habitat impacts could enhance disease risk by increasing contact with domestic animals and by altering patterns of exposure to other wild felids. We performed a serologic survey for feline pathogens in California mountain lions (Puma concolor) using 490 samples from 45 counties collected from 1990 to 2008. Most mountain lions sampled were killed because of depredation or public safety concerns and 75% were adults. Pathogens detected by serosurvey in sampled mountain lions included feline panleukopenia virus (39.0%), feline calicivirus (33.0%), feline coronavirus (FCoV, 15.1%), feline herpesvirus (13.0%), heartworm (12.4%), feline leukemia virus (5.4%), and canine distemper virus (3%). An outbreak of heartworm exposure occurred from 1995 to 2003 and higher than expected levels of FCoV-antibody–positive mountain lions were observed from 2005 to 2008, with foci in southern Mendocino and eastern Lake counties. We show that the majority of mountain lions were exposed to feline pathogens and may be at risk of illness or fatality, particularly kittens. Combined with other stressors, such as ongoing habitat loss, infectious disease deserves recognition for potential negative impact on mountain lion health and population viability.

EFFICACY OF A TYPE C BOTULISM VACCINE IN GREEN-WINGED TEAL

We tested the efficacy of a single dose of Botumink® toxoid for protecting wild green-winged teal (Anas crecca) during botulism epizootics caused by Clostridium botulinum type C. We challenged control and immunized ducks with four different doses of type C botulinum toxin to determine the LD50 for this species and to evaluate vaccine protection. Fewer immunized ducks were affected with botulism than control ducks, indicating that a single dose of Botumink® toxoid could increase the survival of ducks during epizootics. However, the frequency of immunized ducks with signs of botulism increased with the challenge dose of botulinum toxin. Even at doses of botulinum toxin approximately 2 to 4 green-winged teal LD50, about 50% of the immunized ducks were affected. We believe an improved vaccine or a better delivery system is required to justify immunization of wild birds for experimental survival studies.