Journal of Wildlife Diseases最新文献

Abstract: Hepatozoon spp. are protozoal organisms that infect a wide variety of animal hosts. Three free-ranging American mink (Neovison vison) from Pennsylvania, USA, were diagnosed with hepatozoonosis either as the primary cause of mortality or as a co-morbidity with canine distemper virus infection or trauma. In all cases, protozoa were detected in the lungs and/or heart with varying severity, as characteristic microgranulomas with intrahistiocytic merozoites as well as fewer distinct meronts. Partial 18S rRNA gene sequence from one case was identical to a Hepatozoon sp. previously detected in mink followed by a Hepatozoon sp. detected in ticks and other mustelid species. This paper expands on the limited knowledge of Hepatozoon spp. infecting North American mustelids and correlates that a previously detected Hepatozoon sp. in mink can cause histopathologic lesions and occasional mortality.

The recent highly pathogenic avian influenza (HPAI) outbreak in Peru devastated seabird populations and was associated with mass mortality events in marine mammals. The first mortality events were observed in coastal Peru in 2022, with the death of hundreds of Peruvian Pelicans (Pelecanus thagus). The outbreak response included health assessments and attempts to use rapid virus detection methods in the field on live and dead birds. Our study compared the FluDETECT Avian rapid antigen screening test that is commonly used in poultry with reverse transcription quantitative PCR (RT-qPCR) for the detection of HPAI virus in Peruvian seabirds. In total, 43 birds across five species were evaluated in this study: Humboldt Penguins (Spheniscus humboldti; n=6), Guanay Cormorants (Leucocarbo bougainvilliorum [Phalacrocorax bougainvillii]; n=19), Peruvian Pelicans (n=13), Kelp Gulls (Larus dominicanus; n=2), and Peruvian Boobies (Sula variegata; n=3). We did not find agreement between the results of the rapid antigen test and the RT-qPCR (Cohen kappa=0.14). The diagnostic sensitivity of the rapid test was low (33%), whereas the specificity was 100%. Based on these findings, we do not recommend the FluDETECT Avian rapid antigen test for influenza screening in seabird species, although given the high specificity, a positive result from this rapid test should be interpreted as a true positive.

Lesion severity scores are often used to monitor individual health outcomes following the incursion of certain wildlife diseases. However, collapsing a complex trait such as pathology onto a single axis can mask critical information about host-pathogen interactions. In this study, we apply multivariate techniques (shape and community analyses) to explore potential patterns of coevolution in a well-studied wildlife disease system: House Finches (Haemorhous mexicanus) infected with Mycoplasma gallisepticum, a bacterium that causes conjunctival pathology that is visible and facilitates transmission. We captured hatch-year House Finches from two USA populations that differ in their history of pathogen exposure: a Virginia population that has experienced seasonal epizootics for >25 yr and a Hawaii population that is naïve to the pathogen. We then experimentally infected the birds with one of two isolates that varied in virulence. The Virginia birds showed milder distortions of the eye rim, reflected as shorter distances traveled through disease space, across isolates than did the Hawaii birds. Although birds expressed an overlapping suite of pathologic descriptors, the high-virulence isolate caused Virginia birds to express certain pathologies at different frequencies, leading to depauperate communities, compared with the Hawaii birds in which pathologies were expressed more evenly. Notably, eversion was expressed in nearly half of all Virginia eye-days (number of days an eye was sampled) with pathology in response to the high-virulence isolate despite relatively mild lesion severity scores. This may indicate that pathologies that can enhance host competence without compromising host fitness will be maintained and even selected for during host-pathogen coevolution, especially in wildlife populations trending toward disease tolerance.

Yellow-eyed Penguins (Megadyptes antipodes; hoiho) are a unique, nationally endangered, and declining species endemic to New Zealand. Between 28 April 2023 and 28 February 2024, histopathologic examination found that six Yellow-eyed Penguins died from septicemia. A Pasteurella sp. was cultured from all six cases and confirmed as Pasteurella multocida in three cases by either MALDI-TOF (n=2) or genome sequencing (n=1). One isolate was confirmed as P. multocida type A:L3 by molecular techniques and genome sequencing. Pasteurella multocida is the causative agent of avian cholera; thus, finding P. multocida confirmed avian cholera as the cause of these deaths. A source for the bacterial infections could not be identified in these cases. Although avian cholera has been previously reported in other penguin species, to our knowledge, these are the first reported cases of P. multocida in Yellow-eyed Penguins. Yellow-eyed Penguins do not nest in dense colonies, and direct contact between birds outside of breeding pairs is irregular, making this case series an unusual presentation for avian cholera. The loss of six individuals, including three of breeding age, will have a significant impact on the mainland Yellow-eyed Penguin population, and the potential for further losses to avian cholera cannot be discounted. This case series illustrates the benefits of multiagency collaboration in monitoring for, and investigation of, potentially new and emerging diseases in threatened species.

We report highly pathogenic avian influenza H5 virus infection in 10 Northern Fulmars (Fulmarus glacialis) found dead throughout January and February 2024 in the Netherlands. Five birds were infected with the H5N5 subtype, notable for markers of adaptation to mammals. Continuous infectious disease surveillance remains important in wild birds.

Rabbit hemorrhagic disease virus 2 (RHDV2) is an emerging virus of lagomorphs, with an extremely high mortality rate. Outbreaks of RHDV2 have been reported in domestic and wild European rabbits (Oryctolagus cuniculus) and wild lagomorphs globally, with the recent emergence and establishment of RHDV2 in the USA in 2018 and 2020, respectively. Here, we describe experimental infections in snowshoe hares (Lepus americanus), a species of conservation interest in the US. In this pilot study that took place January-April 2022, six hares were orally exposed to infectious virus and monitored for clinical signs and viral shedding for 2 wk. Snowshoe hares were relatively resistant to disease, with no hares succumbing to lethal infection during the experimental time frame (14 d) and animals showing histopathologic evidence of recovery from hepatic injury. Liver samples collected postmortem and pooled fecal samples collected daily were PCR positive for RHDV2, indicating that the hares were indeed infected and shedding viral particles. The majority of hares (5/6) seroconverted by the end of the study. These findings suggest that snowshoe hares are susceptible to RHDV2 and can potentially shed virus onto the landscape, but are less likely to be affected clinically than certain other species of lagomorph.

Information on pathogens, including zoonotic agents, in European brown hares (Lepus europaeus) in the Netherlands is lacking. In this paper, we provide an overview of the most common pathogens found in hares in the Netherlands. Specifically, we assessed whether land use and climatic factors influence the occurrence of a frequently detected pathogen in hares, that is, Yersinia spp., and determined whether there are changes in the occurrence of pathogens in hares between the periods 1966-77 and 2009-21. Postmortem examinations were available for 513 hares from 2009 to 2021 and for 757 hares from 1966 to 1977. Descriptive analysis was performed on these data, assessing hare metadata, pathology, reasons for submission, land use surrounding the location of recovery, and seasonality. A logistic mixed modeling approach was used to identify predictors for the presence of Yersinia spp. In both periods, hares were identified as competent hosts for several pathogens, including zoonotic agents. Yersinia spp. was the most frequently identified pathogen (recent period, 12.1%; historic period, 25.1%). Between 2009 and 2021, Yersinia spp. presence was positively associated with the proportion of agricultural land use and negatively associated with the mean daily minimum temperature. The results presented herein provide a better understanding of pathogens circulating in free-ranging hares in the Netherlands and are relevant to hare health and public health and for wildlife managers and future surveillance strategies. Furthermore, the results emphasize the inherent difficulties associated with retrospective analyses of these types of data.

The American bison (Bison bison) is an ecologically, economically, and culturally significant species that is exceptionally vulnerable to disease caused by Mycoplasma bovis. In contrast to livestock in which M. bovis is one of many infectious agents comprising the bovine respiratory disease complex, infection in bison is characterized by severe pneumonia and potential for systemic disease in the absence of coinfecting pathogens. In bison, morbidity and mortality are highest in adult cows, whereas calves and yearlings infrequently present with clinical disease. The infection dynamics of M. bovis in young bison exposed during an outbreak have not been fully characterized. Herein, we describe a severe outbreak of M. bovis in a closed, extensively managed herd from which we established a cohort of young bison for longitudinal observation, sampling, and testing. Our findings indicate that M. bovis can colonize the nasopharynx of calves and yearlings during an outbreak, often without causing apparent clinical signs. Although some animals cleared the infection during a 12-mo follow-up study, others remained PCR and culture positive, highlighting the potential for asymptomatic carriage in bison calves as a source of subsequent outbreaks. Using a paired swabbing approach, we show that sampling the superficial nasal cavity is adequate for detection of M. bovis during an outbreak. Over time, however, deep sampling of the nasopharynx is necessary to maximize detection of subclinical infections. Uncertainty in detection using PCR on nasal swab samples can complicate herd assessments and limit the ability to fully assess risk. This study emphasizes the difficulty of identifying chronic carriers following an outbreak and underscores the need for further research to inform M. bovis management and minimize risk in the sensitive and iconic American bison.

Surveillance is an important component of One Health; however, disease surveillance in wild animals is hindered by challenges in obtaining and preserving adequate biological samples from free-ranging animals. The protozoan Toxoplasma gondii is the etiologic agent causing toxoplasmosis, a worldwide zoonosis with a high prevalence in Brazil. There is limited literature on toxoplasmosis in giant anteaters (Myrmecophaga tridactyla); therefore, this study aimed to evaluate the seroprevalence of T. gondii in M. tridactyla from midwest Brazil. Blood samples from 71 free-ranging animals from the Cerrado (n=65) and Pantanal (n=6) biomes in Mato Grosso do Sul state, were collected from 2016 to 2021, as part of Wild Animals Conservation Institute (ICAS) studies. A modified agglutination test was used to detect anti-T. gondii antibodies. Overall, 62% (44/71) of free-ranging anteaters tested positive, with titers ranging from 16 to 4,096, confirming exposure of giant anteaters in this area of Brazil to T. gondii. Anti-T. gondii antibodies were detected in anteaters from both the Pantanal wetland and Cerrado savanna biomes, indicating the presence of T. gondii in both.

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses that cause severe diseases in domestic cats. Recently, they have emerged as a concern for wild felids. The aim of this study was to evaluate the exposure to feline retroviruses in free-ranging Neotropical wild felids from southern Brazil. A total of 48 road-killed wild felids belonging to three species were sampled: Geoffroy's cat (Leopardus geoffroyi), margay (Leopardus wiedii), and Southern tiger cat (Leopardus guttulus). In addition, 28 domestic cats found inside protected areas were investigated. Both the wild and domestic felids were tested for the presence of FeLV and FIV with lateral flow immunoassay (LFA) and molecular methods. Three wild felids (two Geoffroy's cats and one margay) were positive to FeLV by LFA (antigen), PCR (proviral DNA), and quantitative reverse-transcription PCR (viral RNA). From the 28 free-roaming domestic cats sampled inside protected areas, 10 (35%) were positive for FeLV. None of the domestic or wild felids were positive for FIV. In addition to the occurrence of FeLV in two species of free-ranging Neotropical felids, FeLV-positive domestic cats appear to be relatively common in protected areas from southern Brazil, posing an important risk of FeLV transmission to threatened wild felids inside those areas.