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At least 289 records · Page 16Linked to original sources

Mycoplasma testudineum in free-ranging desert tortoises, Gopherus agassizii

We performed clinico-pathological evaluations of 11 wild Agassiz's desert tortoises (Gopherus agassizii) from a translocation project in the central Mojave Desert, California, USA. Group 1 consisted of nine tortoises that were selected primarily due to serologic status, indicating exposure to Mycoplasma testudineum (seven) or both M. agassizii and M. testudineum (two), and secondarily due to clinical signs of upper respiratory tract disease (URTD). Group 2 consisted of two tortoises that were antibody-negative for Mycoplasma and had no clinical signs of URTD, but did have other signs of illness. Of the Group 1 tortoises, M. testudineum, but not M. agassizii, was amplified by polymerase chain reaction and DNA fingerprinted from two tortoises. Using light microscopy, mild to severe pathologic changes were observed in one or more histologic sections of either one or both nasal cavities of each tortoise in Group 1. Our findings support a causal relationship between M. testudineum and URTD in desert tortoises.

California↗

A serosurvey of Greater Sage-grouse ( Centrocercus urophasianus ) in Nevada, USA

To better understand the potential avian diseases in Greater Sage-grouse ( Centrocercus urophasianus ) in the Great Basin in Nevada, we collected 31 blood samples March–April 2014 and tested for antibodies to eight viruses and two bacteria. Specifically, sera were tested for antibodies to avian leukosis virus type A, B, and J (ALV-A, ALV-B, and ALV-J, respectively), infectious bursal disease virus, infectious bronchitis virus, reticuloendothelial virus, avian influenza virus (AIV), West Nile virus, Pasteurella multocida (PM), and Salmonella enterica serovar Pullorum. Serum antibodies against ALV-A and -B (1/31, 3%), ALV-J (5/31, 16%), PM (1/31, 3%), and AIV (2/31, 6%) were detected by enzyme-linked immunosorbent assay (ELISA). While ELISA tests used have only been validated in domestic poultry, the serologic data should be used as a potential indicator of the range of bacterial and viral infectious agents that can infect the Greater Sage-grouse.

Nevada↗

Outbreak of avian cholera on the wintering grounds of the Mississippi Valley Canada goose flock

Avian cholera is reported for the first time in Canada geese, Branta canadensis , of the Mississippi Valley population. The disease was detected in weekly surveillance transects and was responsible to the loss of about 850 geese during the winter of 1978–1979 at localized areas in southern Illinois. Necropsies performed on 480 geese that died at Union County Conservation Area and on 133 birds at Horseshoe Lake Conservation Area during January and February 1979 revealed that the majority of losses (649%) were caused by avian cholera. Lead poisoning was responsible for the death of 14% of the geese analyzed and the remaining 22%, most of which were decomposed, were undiagnosed. Lethal lead levels and Pasteurella multocida occurred concomitantly in a few instances.

Illinois↗

Moderate susceptibility to subcutaneous plague (Yersinia pestis) challenge in vaccine-treated and untreated Sonoran deer mice (Peromyscus maniculatus sonoriensis) and northern grasshopper mice (Onychomys leucogaster)

The variable response of wild mice to Yersinia pestis infection, the causative agent of plague, has generated much speculation concerning their role in the ecology of this potentially lethal disease. Researchers have questioned the means by which Y. pestis is maintained in nature and also sought methods for managing the disease. Here we assessed the efficacy of a new tool, the sylvatic plague vaccine (SPV), in wild-caught northern grasshopper mice ( Onychomys leucogaster ) and commercially acquired Sonoran deer mice ( Peromyscus maniculatus sonoriensis ). More than 40% of the animals survived a subcutaneous Y. pestis challenge of 175,000 colony forming units (over 30,000 times the white mouse 50% lethal dose) in both vaccine-treated and control groups. Our results indicate that SPV distribution is unlikely to protect adult mice from plague infection in field settings and corroborate the heterogeneous response to Y. pestis infection in mice reported by others.

Journal of Wildlife Diseases↗

Winter mortality of common loons in Florida coastal waters

Diagnostic findings are presented for 434 common loons (Gavia imrner) found sick or dead on Florida beaches from 1970 through 1994, primarily during the months of December to April. The most commonly recognized problem was an emaciation syndrome (66%), followed by oiling (18%), aspergillosis (7%), trauma (5%) and miscellaneous disease entities (1%). The cause-of-death for 3% of the birds was not determined. Many of the carcasses examined (n = 173) were obtained during an epizootic which occurred from January to March of 1983 in which more than 13,000 loons were estimated to have died. An emaciation syndrome, characterized by severe atrophy of pectoral muscles, loss of body fat and hemorrhagic enteritis, was the primary finding in this epizootic. It was postulated to have a complex etiologic basis involving synergistic effects and energy costs of migration, molting and replacement of flight feathers, food resource changes, salt-loading, intestinal parasitism, environmental contaminants, and inclement weather.

Florida↗

In vitro growth of the bacterial kidney disease organism Renibacterium salmoninarum on a nonserum, noncharcoal-based "homospecies-metabolite" medium

Laboratory and field trials were conducted to evaluate in vitro growth of Renibacterium salmoninarum in media without serum or charcoal. Growth of this bacterium, the cause of bacterial kidney disease (BKD) in salmonids, is accelerated by addition of a growth enhancing “metabolite” of unknown composition to KDM2 medium, the medium commonly used for isolation of R. salmoninarum . KDM2 medium supplemented with greater than 1% (v/v) metabolite enhanced growth even without addition of either serum or charcoal. Medium containing 5% metabolite (denoted Five-M) allowed optimal growth in laboratory studies and was further evaluated as a primary plating medium for recovery of the bacterium isolated from chinook salmon ( Oncorhynchus tshawytscha ) exhibiting clinical BKD. Recovery rates of R. salmoninarum using Five-M medium were 4% and 36% higher, respectively, than comparable rates using a serum-based medium for the two salmon populations evaluated. Five-M medium is an effective, inexpensive alternative to serum-based or charcoal-based media.

Journal of Wildlife Diseases↗

Clinical pathology and assessment of pathogen exposure in southern and Alaskan sea otters

The southern sea otter ( Enhydra lutris nereis ) population in California (USA) and the Alaskan sea otter ( E. lutris kenyoni ) population in the Aleutian Islands (USA) chain have recently declined. In order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 through 2000. Samples from 72 free-ranging Alaskan, 78 free-ranging southern, and (for pathogen exposure only) 41 debilitated southern sea otters in rehabilitation facilities were evaluated and compared to investigate regional differences. Serum chemistry and hematology values did not indicate a specific disease process as a cause for the declines. Statistically significant differences were found between free-ranging adult southern and Alaskan population mean serum levels of creatinine kinase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, calcium, cholesterol, creatinine, glucose, phosphorous, total bilirubin, blood urea nitrogen, and sodium. These were likely due to varying parasite loads, contaminant exposures, and physiologic or nutrition statuses. No free-ranging sea otters had signs of disease at capture, and prevalences of exposure to calicivirus, Brucella spp., and Leptospira spp. were low. The high prevalence (35%) of antibodies to Toxoplasma gondii in free-ranging southern sea otters, lack of antibodies to this parasite in Alaskan sea otters, and the pathogen's propensity to cause mortality in southern sea otters suggests that this parasite may be important to sea otter population dynamics in California but not in Alaska. The evidence for exposure to pathogens of public health importance (e.g., Leptospira spp., T. gondii ) in the southern sea otter population, and the naïveté of both populations to other pathogens (e.g., morbillivirus and Coccidiodes immitis ) may have important implications for their management and recovery.

Journal of Wildlife Diseases↗

Fipronil pellets reduce flea abundance on black-tailed prairie dogs: Potential tool for plague management and black-footed ferret conservation

In western North America, sylvatic plague (a flea-borne disease) poses a significant risk to endangered black-footed ferrets ( Mustela nigripes ) and their primary prey, prairie dogs ( Cynomys spp.). Pulicides (flea-killing agents) can be used to suppress fleas and thereby manage plague. In South Dakota, US, we tested edible “FipBit” pellets, each containing 0.84 mg fipronil, on free-living black-tailed prairie dogs ( Cynomys ludivicianus ). FipBits were applied along transects at 125 per ha and nearly eliminated fleas for 2 mo. From 9–14 mo post-treatment, we found only 10 fleas on FipBit sites versus 1,266 fleas on nontreated sites. This degree and duration of flea control should suppress plague transmission. FipBits are effective, inexpensive, and easily distributed but require federal approval for operational use.

South Dakota↗

Oxalosis in wild desert tortoises, Gopherus agassizii

We necropsied a moribund, wild adult male desert tortoise ( Gopherus agassizii ) with clinical signs of respiratory disease and elevated plasma biochemical analytes indicative of renal disease (blood urea nitrogen [415 mg/dl], uric acid [11.8 mg/dl], sodium >180 mmol/l] and chloride [139 mmol/l]). Moderate numbers of birefringent oxalate crystals, based on infrared and electron microscopy, were present within renal tubules; small numbers were seen in colloid within thyroid follicles. A retrospective analysis of 66 additional cases of wild desert tortoises was conducted to determine whether similar crystals were present in thyroid and kidney. The tortoises, from the Mojave and Sonoran deserts, were necropsied between 1992 and 2003 and included juveniles and adults. Tortoises were classified as healthy (those that died due to trauma and where no disease was identified after necropsy and evaluation by standard laboratory tests used for other tortoises) or not healthy (having one or more diseases or lesions). For all 67 necropsied tortoises, small numbers of crystals of similar appearance were present in thyroid glands from 44 of 54 cases (81%) and in kidneys from three of 65 cases (5%). Presence of oxalates did not differ significantly between healthy and unhealthy tortoises, between age classes, or between desert region, and their presence was considered an incidental finding. Small numbers of oxalate crystals seen within the kidney of two additional tortoises also were considered an incidental finding. Although the source of the calcium oxalate could not be determined, desert tortoises are herbivores, and a plant origin seems most likely. Studies are needed to evaluate the oxalate content of plants consumed by desert tortoises, and particularly those in the area where the tortoise in renal failure was found.

Journal of Wildlife Diseases↗

Detection of Mycoplasma agassizii in the Texas Tortoise (Gopherus berlandieri)

Mycoplasma agassizii causes upper respiratory tract disease (URTD) in Texas tortoises (Gopherus berlandieri). To determine exposure to and shedding of M. agassizii, we collected blood samples and nasal swabs from 40 free-ranging Texas tortoises on public and private lands in Texas, USA, from May to October 2009. We used an enzyme-linked immunosorbent assay (ELISA) to detect M. agassizii–specific antibodies. Eleven (28%) tortoises were antibody positive, three (8%) were suspect, and the remaining 26 (65%) were negative. Nasal lavage samples were collected from 35 of the 40 tortoises for M. agassizii culture and PCR to detect shedding of M. agassizii. Current infection with M. agassizii was confirmed in one tortoise that had mild clinical signs of URTD and was positive by ELISA (antibody titer >512), PCR, and culture. The clinical isolate was confirmed as M. agassizii by restriction fragment length polymorphism and immunobinding.

Texas↗

Mortality patterns in endangered Hawaiian geese (Nene; Branta sandvicensis )

Understanding causes of death can aid management and recovery of endangered bird populations. Toward those ends, we systematically examined 300 carcasses of endangered Hawaiian Geese (Nene; Branta sandvicensis ) from Hawaii, Maui, Molokai, and Kauai between 1992 and 2013. The most common cause of death was emaciation, followed by trauma (vehicular strikes and predation), and infectious/inflammatory diseases of which toxoplasmosis (infection with Toxoplasma gondii ) predominated. Toxicoses were less common and were dominated by lead poisoning or botulism. For captive birds, inflammatory conditions predominated, whereas emaciation, trauma, and inflammation were common in free-ranging birds. Mortality patterns were similar for males and females. Trauma predominated for adults, whereas emaciation was more common for goslings. Causes of death varied among islands, with trauma dominating on Molokai, emaciation and inflammation on Kauai, emaciation on Hawaii, and inflammation and trauma on Maui. Understanding habitat or genetic-related factors that predispose Nene (particularly goslings) to emaciation might reduce the impact of this finding. In addition, trauma and infection with T. gondii are human-related problems that may be attenuated if effectively managed (e.g., road signs, enforcement of speed limits, feral cat [ Felis catus ] control). Such management actions might serve to enhance recovery of this endangered species.

Hawaii↗

Comparison of immune responses of brown-headed cowbird and related blackbirds to West Nile and other mosquito-borne encephalitis viruses

The rapid geographic spread of West Nile virus (family Flaviviridae , genus Flavivirus , WNV) across the United States has stimulated interest in comparative host infection studies to delineate competent avian hosts critical for viral amplification. We compared the host competence of four taxonomically related blackbird species (Icteridae) after experimental infection with WNV and with two endemic, mosquito-borne encephalitis viruses, western equine encephalomyelitis virus (family Togaviridae , genus Alphavirus , WEEV), and St, Louis encephalitis virus (family Flaviviridae , genus Flavivirus , SLEV). We predicted differences in disease resistance among the blackbird species based on differences in life history, because they differ in geographic range and life history traits that include mating and breeding systems. Differences were observed among the response of these hosts to all three viruses, Red-winged Blackbirds were more susceptible to SLEV than Brewer's Blackbirds, whereas Brewer's Blackbirds were more susceptible to WEEV than Red-winged Blackbirds. In response to WNV infection, cowbirds showed the lowest mean viremias, cleared their infections faster, and showed lower antibody levels than concurrently infected species. Brown-headed Cowbirds also exhibited significantly lower viremia responses after infection with SLEV and WEEV as well as coinfection with WEEV and WNV than concurrently infected icterids. We concluded that cowbirds may be more resistant to infection to both native and introduced viruses because they experience heightened exposure to a variety of pathogens of parenting birds during the course of their parasitic life style.

Journal of Wildlife Diseases↗

Failure to transmit avian vacuolar myelinopathy to mallard ducks

Avian vacuolar myelinopathy (AVM) is a neurologic disease that has been diagnosed in free-ranging birds in the southeastern United States. Bald eagles ( Haliaeetus leuocephalus ), American coots ( Fulica americana ), and mallards ( Anas platyrhynchos ) have been affected. Previous investigations have not determined the etiology of this disease. In November and December 2002, we attempted to induce AVM in game-farmed mallards through four, 7-day exposure trials. Mallards were housed in six groups of eight, with two of these groups serving as controls. One group was housed with AVM-affected coots; one group was tube fed daily with water from the lake where affected coots were captured; one group was tube fed daily with aquatic vegetation ( Hydrilla verticillata ) from the same lake; and another group was tube fed daily with sediment from the lake. No ducks exhibited clinical neurologic abnormalities consistent with AVM and no evidence of AVM was present at histopathologic examination of brain tissue. Although limitations in sample size, quantity of individual doses, frequency of dose administration, duration of exposure, and timing of these trials restrict the interpretation of the findings, AVM was not readily transmitted by direct contact, water, hydrilla, or sediment in this investigation.

Manitoba, Wisconsin↗

Spread of the Rat Lungworm (Angiostrongylus cantonensis) in Giant African Land Snails (Lissachatina fulica) in Florida, USA

The rat lungworm ( Angiostrongylus cantonensis ) is a parasitic nematode that causes rat lungworm disease. It is the leading cause of eosinophilic meningitis and is a zoonotic health risk. We confirmed the presence of A. cantonensis using species-specific, quantitative PCR in 18 of 50 (36%) giant African land snails ( Lissachatina fulica ) collected from Miami, Florida in May 2013. These snails were collected from seven of 21 core areas that the Florida Department of Agriculture and Consumer Services monitor weekly. Rat lungworms have not previously been identified in these areas. Duplicate DNA extractions of foot muscle tissue from each snail were tested. Of the seven core areas we examined, six were positive for A. cantonensis and prevalence of infection ranged from 27% to 100%. Of the 18 positive snails, only five were positive in both extractions. Our results confirm an increase in the range and prevalence of rat lungworm infection in Miami. We also emphasize the importance of extracting sufficient host tissue to minimize false negatives.

Florida↗

The pathogenesis of clade 2.3.4.4 H5 highly pathogenic avian influenza viruses in Ruddy Duck (Oxyura jamaicensis) and Lesser Scaup (Aythya affinis)

Waterfowl are the natural hosts of avian influenza virus (AIV) and disseminate the virus worldwide through migration. Historically, surveillance and research efforts for AIV in waterfowl have focused on dabbling ducks. The role of diving ducks in AIV ecology has not been well characterized. In this study, we examined the relative susceptibility and pathogenicity of clade 2.3.4.4 H5 highly pathogenic AIV (HPAIV) in two species of diving ducks. Juvenile and adult Ruddy Duck ( Oxyura jamaicensis ) and juvenile Lesser Scaup ( Aythya affinis ) were intranasally inoculated with A/Northern Pintail/WA/40964/2014 H5N2 HPAIV. Additional groups of juvenile Lesser Scaups were inoculated with A/Gyrfalcon/WA/41088/2014 H5N8 HPAIV. The approximate 50% bird infectious doses (BID 50 ) of the H5N2 isolate for adult Ruddy Ducks was <10 2 50% egg infectious doses (EID 50 ) and for the juvenile Lesser Scaups it was <10 4 EID 50 . There were insufficient juvenile Ruddy Ducks to calculate the BID 50 . The BID 50 for the juvenile Lesser Scaups inoculated with the H5N8 isolate was 10 3 EID 50 . Clinical disease was not observed in any group; however, mortality occurred in the juvenile Ruddy Ducks inoculated with the H5N2 virus (three of five ducks), and staining for AIV antigen was observed in numerous tissues from these ducks. One adult Ruddy Duck also died and although it was infected with AIV (the duck was positive for virus shedding and AIV antigen was detected in tissues), it was also infected with coccidiosis. The proportion of ducks shedding virus was related to the dose administered, but the titers were similar among dose groups. The group with the fewest ducks shedding virus was the adult Ruddy Ducks. There was a trend for the Lesser Scaups to shed higher titers of virus than the Ruddy Ducks. No virus shedding was detected after 7 d postinoculation in any group. Similar to dabbling ducks, Lesser Scaups and Ruddy Ducks are susceptible to infection with this H5 HPAIV lineage, although they excrete lower titers of virus.

Journal of Wildlife Diseases↗

Mortality of Rocky Mountain elk in Michigan due to meningeal worm

Mortality from cerebrospinal parelaphostrongylosis caused by the meningeal worm ( Parelaphostrongylus tenuis ) has been hypothesized to limit elk ( Cervus elaphus nelsoni ) populations in areas where elk are conspecific with white-tailed deer ( Odocoileus virginianus ). Elk were reintroduced into Michigan (USA) in the early 1900s and subsequently greatly increased population size and distribution despite sympatric high-density (≥12/km 2 ) white-tailed deer populations. We monitored 100 radio-collared elk of all age and sex classes from 1981–94, during which time we documented 76 mortalities. Meningeal worm was a minor mortality factor for elk in Michigan and accounted for only 3% of mortalities, fewer than legal harvest (58%), illegal kills (22%), other diseases (7%), and malnutrition (4%). Across years, annual cause-specific mortality rates due to cerebrospinal parelaphostrongylosis were 0.033 (SE=0.006), 0.029 (SE=0.005), 0.000 (SE=0.000), and 0.000 (SE=0.000) for calves, 1-yr-old, 2-yr-old, and ≥3-yr-old, respectively. The overall population-level mortality rate due to cerebrospinal parelaphostrongylosis was 0.009 (SE=0.001). Thus, meningeal worm had little impact on elk in Michigan during our study despite greater than normal precipitation (favoring gastropods) and record (≥14 km 2 ) deer densities. Further, elk in Michigan have shown sustained population rates-of-increase of ≥18%/yr and among the highest levels of juvenile production and survival recorded for elk in North America, indicating that elk can persist in areas with meningeal worm at high levels of population productivity. It is likely that local ecologic characteristics among elk, white-tailed deer, and gastropods, and degree of exposure, age of elk, individual and population experience with meningeal worm, overall population vigor, and moisture determine the effects of meningeal worm on elk populations.

Michigan↗

Lethal effects on flea larvae of fipronil in host feces: Potential benefits for plague mitigation

Plague, caused by the bacterium Yersinia pestis , is a zoonotic disease of mammalian hosts and flea vectors. Fipronil baits have been used to suppress adult fleas for plague mitigation. The degree and duration of flea control may increase if fipronil also kills other stages in the flea life cycle. We fed grain treated with 0.005% fipronil by weight, or nontreated grain, to black-tailed prairie dogs ( Cynomys ludovicianus ), which excrete fipronil and metabolites in their feces after consuming fipronil in their diet. We presented prairie dog feces to 331 larval Oropsylla montana (Siphonaptera: Ceratophyllidae). When exposed to feces lacking fipronil or metabolites, 84% of larvae survived for 24 h. In contrast, survival declined to 42% for larvae contacting feces from fipronil-treated prairie dogs. Just 7% of larvae consuming feces from fipronil-treated prairie dogs survived. Fipronil and metabolites may persist in host feces for several months or longer in prairie dog burrows where flea larvae dwell and forage. The lethal effects of fipronil on adult and larval fleas (and perhaps other life stages) may help to explain why fipronil baits are capable of suppressing fleas on prairie dogs for ≥12 mo.

Journal of Wildlife Diseases↗

Mortality from duck plague virus in immunosuppressed adult mallard ducks

Environmental contaminants contain chemicals that, if ingested, could affect the immunological status of wild birds, and in particular, their resistance to infectious disease. Immunosuppression caused by environmental contaminants, could have a major impact on waterfowl populations, resulting in increased susceptibility to contagious disease agents. Duck plague virus has caused repeated outbreaks in waterfowl resulting in mortality. In this study, several doses of cyclophosphamide (CY), a known immunosuppressant, were administered to adult mallards (Anas platyrhynchos) to determine if a resultant decrease in resistance to a normally sub-lethal strain of duck plague virus would occur, and induce mortality in these birds. Death occurred in birds given CY only, and in birds given virus and CY, but not in those given virus only. There was significantly greater mortality and more rapid deaths in the duck plague virus-infected groups than in groups receiving only the immunosuppressant. A positively correlated dose-response effect was observed with CY mortalities, irrespective of virus exposure. A fuel oil and a crude oil, common environmental contaminants with immunosuppressive capabilities, were tested to determine if they could produce an effect similar to that of CY. Following 28 days of oral oil administration, the birds were challenged with a sub-lethal dose of duck plague virus. No alteration in resistance to the virus (as measured by mortality) was observed, except in the positive CY control group.

Journal of Wildlife Diseases↗