Journal of Wildlife Diseases最新文献

Hermaphroditism or intersexuality occurs endogenously in most mammal species. We document the behavior and physical and anatomic appearance of a suspected true hermaphroditic free-ranging wild gray wolf (Canis lupus) in Denali National Park and Preserve, Alaska, USA.

The order Procellariiformes includes several species of seabirds that perform long-distance migrations crossing all the oceans. These movements may contribute to the dispersal and exchange of hemoparasites, such as haemosporidians. There is a lack of studies regarding the order Haemosporida in Procellariiformes, and, to date, only the genus Plasmodium has been reported. This survey investigated the occurrence of the three genera of haemosporidians, Plasmodium, Haemoproteus, and Leucocytozoon, in samples collected between 2013 and 2022 from 95 individuals of 14 species of Procellariiformes from southern Brazil, including live animals in rehabilitation centers, individuals caught as incidental bycatch, and carcasses found along the coast. A total of 171 samples of blood and fragments of liver and spleen were analyzed, with extracted DNA being subjected to a nested PCR followed by phylogeny analysis. All animals were negative for Plasmodium spp. and Leucocytozoon spp., but one Black-browed Albatross (Thalassarche melanophris) and one Manx Shearwater (Puffinus puffinus) specimen were positive for Haemoproteus spp. The sequences obtained from positive seabirds did not show 100% similarity with other known lineages available in the MalAvi database and thus were probably novel lineages. However, one sequence clustered together with Haemoproteus noctuae, a parasite from Strigiformes, while the other was grouped with Haemoproteus columbae, which is classically related to Columbiformes. These results suggest that both positive animals may have become infected when beached or in rehabilitation centers by a spillover of vectors from local birds. This highlights the importance of surveillance of the health of Procellariiformes regarding the possibility of dissemination of new pathogens in different bird populations.

Mass mortality events in wildlife can be indications of an emerging infectious disease. During the spring and summer of 2021, hundreds of dead passerines were reported across the eastern US. Birds exhibited a range of clinical signs including swollen conjunctiva, ocular discharge, ataxia, and nystagmus. As part of the diagnostic investigation, high-throughput metagenomic next-generation sequencing was performed across three molecular laboratories on samples from affected birds. Many potentially pathogenic microbes were detected, with bacteria forming the largest proportion; however, no singular agent was consistently identified, with many of the detected microbes also found in unaffected (control) birds and thus considered to be subclinical infections. Congruent results across laboratories have helped drive further investigation into alternative causes, including environmental contaminants and nutritional deficiencies. This work highlights the utility of metagenomic approaches in investigations of emerging diseases and provides a framework for future wildlife mortality events.

Products of parturition are the predominant source of Brucella abortus for transmission in bison (Bison bison). Our objective was to assess whether preventing pregnancy in Brucella-seropositive bison reduced B. abortus shedding. Brucella-seropositive and -seronegative bison from Yellowstone National Park, Wyoming, USA were used in a replicated experiment. Each of two replicates (rep1, rep2) included a group of seropositive females treated with a single dose of gonadotropin-releasing hormone-based immunocontraceptive (Treatment rep1, n=15; Treatment rep2, n=20) and an untreated group (Control rep1, n=14; Control rep2, n=16) housed separately. Seronegative sentinel females were placed in each group to monitor horizontal transmission. Seronegative males were co-mingled for breeding each year. Pregnant females were removed from treatment groups in the first year, but not thereafter. Each January-June we monitored for B. abortus shedding events-any parturition associated with culture-positive fluids or tissues. We analyzed probability of shedding events using a negative binomial generalized linear mixed model fit by maximum likelihood using Laplace approximation. Over 5 yr, we observed zero shedding events in Treatment rep1 vs. 12 in Control rep1. All five Control rep1 sentinels but zero (0/5) Treatment rep1 sentinels seroconverted. In the second replicate, Treatment rep2 had two shedding events over 3 yr and Control rep2 had five events over 2 yr. Sentinels in both Control rep2 (3/6) and Treatment rep2 (5/6) seroconverted by trial endpoint. Treatment rep1 showed a reduced shedding probability relative to Control rep1, Treatment rep2, and Control rep2 (log odds value -25.36 vs. -1.71, -1.39, and -0.23, respectively). Fixed effect predictor covariates, year and age, had no explanatory value. These data suggest that successful contraception of brucellosis-seropositive female bison prevents shedding of B. abortus by individual animals. However, contraceptive treatment may or may not sufficiently reduce disease transmission to reduce brucellosis prevalence in an affected herd.

The Northern Bobwhite (Colinus virginianus) has been undergoing a range-wide population decline. Potential causes for declines across its historic range have been investigated for decades and include habitat loss and fragmentation and a variety of parasitic and infectious diseases. Although there have been studies on bobwhite ecology in Oklahoma, USA, relatively little is known about parasites and pathogens in the region. We evaluated the health of free-ranging bobwhites from nine sites in western Oklahoma. From 2018 to 2020, 206 bobwhites were evaluated for gross and microscopic lesions and tested for selected pathogens. In general, bobwhites were in good nutritional condition with ample muscle mass and fat stores. No significant gross lesions were observed in any bobwhite and no significant histologic lesions were detected in a subset. There was no evidence of infection with or exposure to reticuloendotheliosis virus, West Nile virus, respiratory Mycoplasmataceae species, Pasteurella multocida, intestinal Eimeria spp., or oral Trichomonas spp. Several pathogens of potential concern were detected, including avian adenovirus (8.6%), Toxoplasma gondii (2.3%), and haemosporidians (a Haemoproteus sp. (1.5%), Leucocytozoon schoutedeni (1.5%), and Plasmodium homopolare haplotype 2 [lineage LAIRI01; 3.6%]). Physaloptera sp. (12%) and Sarcocystis sp. (1%) were detected in the breast muscle. Low intraspecific genetic diversity was noted for Physaloptera sp., and sequences were most similar to Physaloptera sequences from bobwhites and grasshoppers (Orthoptera) in Texas. Low intensities of chewing lice, chiggers, and ticks were observed. A subset of bobwhites had evidence of exposure to selected toxicants and heavy metals; a small number had low levels of iron, manganese, zinc, molybdenum, and copper, which were not considered diagnostically relevant. In general, bobwhites from western Oklahoma appeared to be in good health with a low diversity of pathogens detected, but future work is needed to understand potentially changing disease risks for this population.

Lead (Pb) is a toxic nonessential metal, known mainly for causing poisoning of humans and wild birds. However, little is known about Pb exposure and its associated health effects in wild mammals. We conducted a global systematic literature review to identify peer-reviewed studies published on Pb exposure in wild mammalian species and the health effects they identified. In total, 183 studies, conducted in 35 countries and published over 62 yr (1961-2022), were included in the review. Only 6% (11/183) of the studies were conducted in developing countries. Although 153 mammalian species were studied, most studies focused on species that are easy to access (i.e., hunted species and small mammals that are easy to trap). Therefore, carnivores and scavengers were less frequently studied than herbivores and omnivores. Despite all studies reporting Pb concentrations, only 45 (25%) studies investigated health effects and, of these 45 studies, only 28 (62%) found any health effect in 57 species. All health effects were negative and ranged from subclinical effects to fatality. Methodologies of Pb sampling and quantification and reporting of results varied widely across the studies, making both Pb concentrations and health effects difficult to compare and evaluate. Thus, there is a need for more research on Pb exposure and its health effects on wild mammals, especially as carnivores and scavengers could be used as sentinels for ecosystem health.

The purpose of this study was to determine if the number of pregnancies in naturally infected Brucella abortus-positive bison (Bison bison) cows would be reduced over a period of 5 yr after one treatment with 3000 µg gonadotropin-releasing hormone immunocontraceptive (GonaCon) compared to a similar group of naturally infected B. abortus-positive bison cows not treated with GonaCon. In each of the 5 yr, GonaCon-treated cows produced fewer offspring in relation to number of cows than the nontreated cows. Fisher's Exact test comparing offspring produced during the first reproductive season showed a significant difference between the two groups (P=0.0028). Differences in number of calves produced in GonaCon-treated and control groups were also noted in remaining years, but statistics were not applied because of data constraints. These data indicate that one treatment with GonaCon in brucellosis-seropositive female bison reduced pregnancies over five reproductive years. Thus, immunocontraception could potentially be used to manage brucellosis in affected herds.

The long-term mitigation of human-domestic animal-wildlife conflicts is complex and difficult. Over the last 50 yr, the primary biomedical concepts and actualized collaborative global field applications of oral rabies vaccination to wildlife serve as one dramatic example that revolutionized the field of infectious disease management of free-ranging animals. Oral vaccination of wildlife occurred in diverse locales within Africa, Eurasia, the Middle East, and North America. Although rabies is not a candidate for eradication, over a billion doses of vaccine-laden baits distributed strategically by hand, at baiting stations, or via aircraft, resulted in widespread disease prevention, control, or local disease elimination among mesocarnivores. Pure, potent, safe, and efficacious vaccines consisted of either modified-live, highly attenuated, or recombinant viruses contained within attractive, edible baits. Since the late 1970s, major free-ranging target species have included coyotes (Canis latrans), foxes (Urocyon cinereoargenteus; Vulpes vulpes), jackals (Canis aureus; Lupulella mesomelas), raccoons (Procyon lotor), raccoon dogs (Nyctereutes procyonoides), and skunks (Mephitis mephitis). Operational progress has occurred in all but the latter species. Programmatic evaluations of oral rabies vaccination success have included: demonstration of biomarkers incorporated within vaccine-laden baits in target species as representative of bait contact; serological measurement of the induction of specific rabies virus neutralizing antibodies, indicative of an immune response to vaccine; and most importantly, the decreasing detection of rabies virus antigens in the brains of collected animals via enhanced laboratory-based surveillance, as evidence of management impact. Although often conceived mistakenly as a panacea, such cost-effective technology applied to free-ranging wildlife represents a real-world, One Health application benefiting agriculture, conservation biology, and public health. Based upon lessons learned with oral rabies vaccination of mesocarnivores, opportunities for future extension to other taxa and additional diseases will have far-reaching, transdisciplinary benefits.

This article reports on respiratory function in white rhinoceros (Ceratotherium simum) immobilized with etorphine-azaperone and the changes induced by butorphanol administration as part of a multifaceted crossover study that also investigated the effects of etorphine or etorphine-butorphanol treatments. Six male white rhinoceros underwent two immobilizations by using 1) etorphine-azaperone and 2) etorphine-azaperone-butorphanol. Starting 10 min after recumbency, arterial blood gases, limb muscle tremors, expired minute ventilation, and respiratory rate were evaluated at 5-min intervals for 25 min. Alveolar to arterial oxygen gradient, expected respiratory minute volume, oxygen consumption, and carbon dioxide production were calculated. Etorphine-azaperone administration resulted in hypoxemia and hypercapnia, with increases in alveolar to arterial oxygen gradient, oxygen consumption, and carbon dioxide production, and a decrease in expired minute ventilation. Muscle tremors were also observed. Intravenous butorphanol administration in etorphine-azaperone-immobilized white rhinoceros resulted in less hypoxemia and hypercapnia; a decrease in oxygen consumption, carbon dioxide production, and expired minute ventilation; and no change in the alveolar to arterial oxygen gradient and rate of breathing. We show that the immobilization of white rhinoceros with etorphine-azaperone results in hypoxemia and hypercapnia and that the subsequent intravenous administration of butorphanol improves both arterial blood oxygen and carbon dioxide partial pressures.

Sarcoptic mange caused by Sarcoptes scabiei can have catastrophic consequences for wildlife. We inspected 122 Andean foxes (Lycalopex culpaeus), collected by active (n=66) or passive (n=56) surveillance, and 28 South American gray foxes (Lycalopex griseus; all from passive surveillance) for mange in Chile (2015-19). In Andean foxes, gross lesions of mange were diagnosed in 24% of passively and 9% of actively collected foxes, although observed prevalences might be underestimated. Seroprevalence was 37 and 18%, respectively, indicating that some individuals recovered from infection or were developing the disease. No differences were found between age and sex groups. Comparing data from passive surveillance, occurrence of gross lesions was lower in gray foxes (5%). Body condition was significantly better in Andean foxes without lesions than in diseased foxes, which had significantly lower albumin concentrations than healthy individuals. Among the 12 foxes with gross lesions, four, six and two individuals were categorized as having type I, type II, and type III lesions, respectively, based on clinical severity. Histologic severity correlated with gross lesions and included irregular epidermal hyperplasia with hyperkeratosis, which was marked in type II and III infections. Conventional PCR targeting of the cox1 gene fragment revealed four nucleotide sequence types, showing 99-100% identity among them and between 99% and 100% identity with previously published sequences of S. scabiei. A significant association between the occurrence of mange in foxes and distance to the nearest house was found. We speculate that diseased foxes tended to approach human settlements, perhaps in search of food. Visual inspection of 211 rural dogs from the study area did not reveal gross mange lesions in any animal. Sarcoptic mange is enzootic in the Andean fox in the study area and should be considered in the management of the species.