Wildlife Disease Research Articles

Wildlife health surveillance: gaps, needs and opportunities.

Disease emergence represents a global threat to public health, economy and biological conservation. Most emerging zoonotic diseases have an animal origin, most commonly from wildlife. To prevent their spread and to support the implementation of control measures, disease surveillance and reporting systems are needed, and due to globalisation, these activities should be carried out at the global level. To define the main gaps affecting the performance of wildlife health surveillance and reporting systems globally, the authors analysed data from a questionnaire sent to National Focal Points of the World Organisation for Animal Health that inquired on structure and limits of wildlife surveillance and reporting systems in their territories. Responses from 103 Members, covering all areas of the globe, revealed that 54.4% have a wildlife disease surveillance programme and 66% have implemented a strategy to manage disease spread. The lack of dedicated budget affected the possibility of outbreak investigations, sample collection and diagnostic testing. Although most Members maintain records relating to wildlife mortality or morbidity events in centralised databases, data analysis and disease risk assessment are reported as priority needs. The authors' evaluation of surveillance capacity found an overall low level, with marked variability among Members that was not restricted to a specific geographical area. Increased wildlife disease surveillance globally would help in understanding and managing risks to animal and public health. Moreover, consideration of the influence of socio-economic, cultural and biodiversity aspects could improve disease surveillance under a One Health approach.

Spatial and temporal responses to incentives: An application to wildlife disease management

When participating in recreation individuals decide on where to go (locations) and when to participate (which time periods), and they respond to changes in external factors (e.g., environmental quality changes, provision of incentives). In examining economic decision-making, economists focus mostly on location choices, thus the behavioral and welfare impacts of the incentives associated with time choices are largely unknown. In this paper, we develop and estimate a flexible econometric model that combines spatial and temporal choices. The model is applied to examine individuals’ location and time choices of their recreation trips in response to extended recreation seasons that are proposed to encourage hunting for wildlife disease management. The data are from an online revealed and stated preference survey of recreational hunters in Alberta, Canada. We find that individuals substitute activities spatially and temporally, take more hunting trips, and gain welfare benefits when they can more flexibly choose the time of activities. Our findings show that increases in time flexibility can be used as an incentive to encourage beneficial outcomes.

A behavioral economic assessment of the role of stakeholder preferences in managing an infectious wildlife disease

AbstractChronic wasting disease (CWD) in cervid populations poses substantial economic costs, and its management is resource intensive. Control of CWD is often subject to stakeholder‐dependent strategies that require active support and participation. The development of effective CWD management strategies and policies hinges on understanding stakeholder preferences, values and decision‐making behavior. Here we provide a basis for understanding the economic impacts of CWD, which are key to developing effective management strategies. We analyze stakeholder incentives from an economic perspective and discuss the effectiveness of prior management and eradication strategies. Our analysis discusses the integration of behavioral economics into evaluations of stakeholder preferences and its effect on decision‐making to produce optimal policy and management outcomes.

Knowledge, Attitudes, and Practices of Communal Livestock Farmers regarding Animal Health and Zoonoses in Far Northern KwaZulu-Natal, South Africa.

The presence of zoonotic diseases adversely affects livestock production and farmers' livelihood in communal areas. A lack of awareness about zoonotic diseases among rural farmers results in economic losses and health risks. The far north-eastern corner of KwaZulu-Natal (KZN) province, South Africa, is home to large numbers of communal livestock farmers who live adjacent to wildlife reserves and international borders. There have been reports of zoonotic and trade-sensitive diseases in the area, but farmers' knowledge, attitudes, and practices (KAP) in this regard are poorly understood. This study investigated the KAPs of communal livestock farmers in far northern KZN regarding livestock and zoonotic diseases found in the livestock-wildlife interface and determined the constraints and challenges faced by communal livestock farmers. A cross-sectional questionnaire survey was conducted among 504 livestock farmers at 45 dip tanks between August and November 2020, using a closed-ended questionnaire. Although the overall level of knowledge regarding animal disease transmission was fairly good (score: 53.2%), 25.4% and 21.4% of farmers had moderate and poor knowledge, respectively, about zoonotic disease transmission and prevention. Over 40% of the farmers were not aware of the zoonotic nature of wildlife and livestock diseases. Older farmers, despite their lower level of education, were more knowledgeable on animal diseases and had better practices in regard to zoonotic disease prevention and management compared to younger ones. The majority of farmers cited the lack of water, insufficient grazing land, stock theft, the restriction of animal movement, and animal diseases as the most significant challenges they faced regarding animal production. The results indicate the need for extension programs that target educating livestock farmers to improve their knowledge of these diseases.

Engaging stakeholders in wildlife disease management: Hunters' willingness to adopt and support biosecurity actions to prevent the spread of rabbit hemorrhagic disease

AbstractRabbit hemorrhagic disease virus 2 (RHDV2) is a highly contagious virus that primarily infects rabbits and hares (lagomorphs) and poses a serious threat to lagomorph populations and hunting. Wildlife agencies in the United States rely on hunters to report RHDV2‐related mortalities and engage in voluntary biosecurity actions to prevent the spread of RHDV2. From April 2021 to April 2022, we conducted a nationwide survey of 22,511 hunters to ascertain their willingness to engage in voluntary biosecurity actions and support government‐mandated biosecurity measures. Respondents expressed greatest willingness to report suspicious lagomorph deaths to wildlife agencies. Respondents' willingness to engage in or support biosecurity actions was positively correlated with their risk perceptions pertaining to lagomorph deaths and the economic impacts of RHDV2, perceptions of the importance of biosecurity, and trust in state agencies to manage RHDV2. We found evidence that respondents' willingness to engage in or support biosecurity actions was also positively correlated with their knowledge of RHDV2. Wildlife agencies should clearly communicate about RHDV2 and its adverse impacts on lagomorphs, biodiversity, and hunting to engage hunters in biosecurity measures. Hunters can provide valuable information about lagomorph population trends and mortality events in the areas they hunt, a cost‐effective method to augment agency surveillance.

Habitat connectivity and host relatedness influence virus spread across an urbanising landscape in a fragmentation-sensitive carnivore.

Spatially heterogeneous landscape factors such as urbanisation can have substantial effects on the severity and spread of wildlife diseases. However, research linking patterns of pathogen transmission to landscape features remains rare. Using a combination of phylogeographic and machine learning approaches, we tested the influence of landscape and host factors on feline immunodeficiency virus (FIVLru) genetic variation and spread among bobcats (Lynx rufus) sampled from coastal southern California. We found evidence for increased rates of FIVLru lineage spread through areas of higher vegetation density. Furthermore, single-nucleotide polymorphism (SNP) variation among FIVLru sequences was associated with host genetic distances and geographic location, with FIVLru genetic discontinuities precisely correlating with known urban barriers to host dispersal. An effect of forest land cover on FIVLru SNP variation was likely attributable to host population structure and differences in forest land cover between different populations. Taken together, these results suggest that the spread of FIVLru is constrained by large-scale urban barriers to host movement. Although urbanisation at fine spatial scales did not appear to directly influence virus transmission or spread, we found evidence that viruses transmit and spread more quickly through areas containing higher proportions of natural habitat. These multiple lines of evidence demonstrate how urbanisation can change patterns of contact-dependent pathogen transmission and provide insights into how continued urban development may influence the incidence and management of wildlife disease.

The role of invasive alien species in the emergence and spread of zoonoses

The role of invasive alien species in the transmission dynamics of zoonotic pathogens is often overlooked, despite the rapid escalation in biological invasions globally. Here we synthesise available information on the influence of invasive alien species on zoonotic pathogen dynamics in invaded ranges, focussing on Europe, and identify key associated knowledge gaps. We identified 272 documented interactions between alien species and zoonotic pathogens within invaded ranges. The majority of these involved invasive alien mammals followed by birds with only a few occurrences of other taxa documented. A wide range of potential interactions between invasive alien species and zoonotic pathogens were identified but few studies considered transmission to humans and so there was limited evidence of actual impacts on human health. However, there is an urgent need to raise awareness of the potential risks posed to human health by the transmission of zoonotic diseases by invasive alien species; the role of invasive alien species in zoonotic disease transmission may exceed that of native wildlife and occur in a relatively short period following the arrival of an invasive alien species within a new region. Ecological and social mechanisms govern the dynamics of zoonotic disease transmission but wildlife diseases are not consistently included within animal, plant and human policies. Rapid advances in the development of systems frameworks that integrate the ecological, economic and social processes promoting spillover in rapidly changing environments will increase understanding to inform decision-making.

WildHealthNet: Supporting the development of sustainable wildlife health surveillance networks in Southeast Asia

Wildlife and wildlife interfaces with people and livestock are essential surveillance targets to monitor emergent or endemic pathogens or new threats affecting wildlife, livestock, and human health. However, limitations of previous investments in scope and duration have resulted in a neglect of wildlife health surveillance (WHS) systems at national and global scales, particularly in lower and middle income countries (LMICs).Building on decades of wildlife health activities in LMICs, we demonstrate the implementation of a locally-driven multi-pronged One Health approach to establishing WHS in Cambodia, Lao PDR and Viet Nam under the WildHealthNet initiative. WildHealthNet utilizes existing local capacity in the animal, public health, and environmental sectors for event based or targeted surveillance and disease detection. To scale up surveillance systems to the national level, WildHealthNet relies on iterative field implementation and policy development, capacity bridging, improving data collection and management systems, and implementing context specific responses to wildlife health intelligence.National WHS systems piloted in Cambodia, Lao PDR, and Viet Nam engaged protected area rangers, wildlife rescue centers, community members, and livestock and human health sector staff and laboratories. Surveillance activities detected outbreaks of H5N1 highly pathogenic avian influenza in wild birds, African swine fever in wild boar (Sus scrofa), Lumpy skin disease in banteng (Bos javanicus), and other endemic zoonotic pathogens identified as surveillance priorities by local stakeholders. In Cambodia and Lao PDR, national plans for wildlife disease surveillance are being signed into legislation.Cross-sectoral and trans-disciplinary approaches are needed to implement effective WHS systems. Long-term commitment, and paralleled implementation and policy development are key to sustainable WHS networks. WildHealthNet offers a roadmap to aid in the development of locally-relevant and locally-led WHS systems that support the global objectives of the World Organization for Animal Health's Wildlife Health Framework and other international agendas.

Urinary neopterin reflects immunological variation associated with age, helminth parasitism, and the microbiome in a wild primate.

Neopterin, a product of activated white blood cells, is a marker of nonspecific inflammation that can capture variation in immune investment or disease-related immune activity and can be collected noninvasively in urine. Mounting studies in wildlife point to lifetime patterns in neopterin related to immune development, aging, and certain diseases, but rarely are studies able to assess whether neopterin can capture multiple concurrent dimensions of health and disease in a single system. We assessed the relationship between urinary neopterin stored on filter paper and multiple metrics of health and disease in wild geladas (Theropithecus gelada), primates endemic to the Ethiopian highlands. We tested whether neopterin captures age-related variation in inflammation arising from developing immunity in infancy and chronic inflammation in old age, inflammation related to intramuscular tapeworm infection, helminth-induced anti-inflammatory immunomodulation, and perturbations in the gastrointestinal microbiome. We found that neopterin had a U-shaped relationship with age, no association with larval tapeworm infection, a negative relationship with metrics related to gastrointestinal helminth infection, and a negative relationship with microbial diversity. Together with growing research on neopterin and specific diseases, our results demonstrate that urinary neopterin can be a powerful tool for assessing multiple dimensions of health and disease in wildlife.

Experimental water hyacinth invasion and destructive management increase human schistosome transmission potential.

Invasive species cause environmental degradation, decrease biodiversity, and alter ecosystem function. Invasions can also drive changes in vector-borne and zoonotic diseases by altering important traits of wildlife hosts or disease vectors. Managing invasive species can restore biodiversity and ecosystem function, but it may have cascading effects on hosts, parasites, and human risk of infection. Water hyacinth, Eichhornia crassipes, is an extremely detrimental invader in many sites of human schistosome transmission, especially in Lake Victoria, where hyacinth is correlated with high snail abundance and hotspots of human schistosome infection. Hyacinth is often managed via removal or in situ destruction, but the effects of these strategies on snail intermediate hosts and schistosomes are not known. We evaluated the effects of water hyacinth invasion and these management strategies on the dynamics of human schistosomes, Schistosoma mansoni, and snails, Biomphalaria glabrata, in experimental mesocosms over 17 weeks. We hypothesized that hyacinth, which is inedible to snails, would affect snail growth, reproduction, and cercariae production through the balance of its competitive effects on edible algae and its production of edible detritus. We predicted that destruction would create a pulse of edible detrital resources, thereby increasing snail growth, reproduction, and parasite production. Conversely, we predicted that removal would have small or negligible effects on snails and schistosomes, because it would alleviate competition on edible algae without generating a resource pulse. We found that hyacinth invasion suppressed algae, changed the timing of peak snail abundance, and increased total production of human-infectious cercariae ~6-fold relative to uninvaded controls. Hyacinth management had complex effects on algae, snails, and schistosomes. Removal increased algal growth and snail abundance (but not biomass), and slightly reduced schistosome production. In contrast, destruction increased snail biomass (but not abundance), indicating increases in body size. Destruction caused the greatest schistosome production (10-fold more than the control), consistent with evidence that larger snails with greater access to food are most infectious. Our results highlight the dynamic effects of invasion and management on a globally impactful human parasite and its intermediate host. Ultimately, preventing or removing hyacinth invasions would simultaneously benefit human and environmental health outcomes.

Relationship between Blood Parameters and Outcome in Rescued Roe Deer.

Veterinary facility admissions of wild animals are increasing alongside the interest in wildlife diseases. To improve animal welfare, it is therefore important to increase veterinarians' knowledge of wild animal medicine and to improve the clinical and diagnostic procedures, especially in the case of patients affected by trauma or multiple traumas. Blood analysis can be a quick and minimally invasive way of gathering useful clinical information for adequate treatment and management, and, together with a good clinical examination, to help predict hospitalisation outcomes. Few papers have reported reference ranges for the haematological and biochemical parameters of roe deer. This study evaluates the haematological and biochemical parameters in traumatised roe deer in relation to animal hospitalisation outcomes. The study was carried out on a cohort of 98 roe deer divided into groups according to their age and hospitalisation outcome. For each animal, a panel of haematological and biochemical parameters was performed. Significant differences were found between unweaned (<4 months old) groups in terms of MCV, MCH, CK, creatinine, total bilirubin, direct bilirubin, and indirect bilirubin, and between weaned (>4 months old) groups for total bilirubin. Creatine kinase, creatinine, and bilirubin may be useful indicators to correlate with the severity of trauma and help predict prognosis.

Influence of alternating electromagnetic field on somatic reactions of pathogens

Outbreaks of new infectious diseases are occurring with increasing frequency and consequences, including wildlife diseases and zoonoses. The increasing emergence of infectious pathogens has many causes, all related to increasing anthropogenic impacts on nature. Some studies show how exposure to fields can enhance or reduce cellular activity, with possible application implications in the field of biotechnology. The effects of magnetic fields at the cellular level in microbial cells may include cell viability and proliferation, apoptosis, morphological changes, changes in metabolic and enzymatic activities, changes in ion transport into the cell, and genotoxicity and changes in gene expression. The aim of this study was to determine the differences in the somatic response of pathogen cells used in biotechnological processes exposed to an alternating electromagnetic field with a constant frequency of 50 Hz in three variants of exposure time. It was found that stimulation with an alternating electromagnetic field affects the somatic responses of microorganisms represented by their growth. The responses of the studied microorganisms are also related to their morphology.

Chemical and Physical Restraint of African Wild Animals.

Book reviews express the opinions of the individual authors regarding the value of the book's content for Journal of Wildlife Diseases Readers. The reviews are subjective assessments and do not necessarily reflect the opinions of the editors, nor do they establish any official policy of the Wildlife Disease Association.

Incorporating Microbial Species Interaction in Management of Freshwater Toxic Cyanobacteria: A Systems Science Challenge.

Water resources are critically important, but also pose risks of exposure to toxic and pathogenic microbes. Increasingly, a concern is toxic cyanobacteria, which have been linked to the death and disease of humans, domesticated animals, and wildlife in freshwater systems worldwide. Management approaches successful at reducing cyanobacterial abundance and toxin production have tended to be short-term solutions applied on small scales (e.g., algaecide application) or solutions that entail difficult multifaceted investments (e.g., modification of landscape and land use to reduce nutrient inputs). However, implementation of these approaches can be undermined by microbial species interactions that (a) provide toxic cyanobacteria with protection against the method of control or (b) permit toxic cyanobacteria to be replaced by other significant microbial threats. Understanding these interactions is necessary to avoid such scenarios and can provide a framework for novel strategies to enhance freshwater resource management via systems science (e.g., pairing existing physical and chemical approaches against cyanobacteria with ecological strategies such as manipulation of natural enemies, targeting of facilitators, and reduction of benthic occupancy and recruitment). Here, we review pertinent examples of the interactions and highlight potential applications of what is known.

Time to consider pharmacological interventions against infectious disease in wildlife

Abstract Interventions against infectious diseases in wildlife are increasingly necessary but remain problematic. Dissimilar to public and domestic animal health, pharmacological interventions (PIs) are rarely used against disease in wildlife populations. However, drugs can combat a range of pathogen types while aligning with positive ethical, epidemiological, evolutionary and socio‐economic outcomes. We discuss how recent conceptual and technological advances could overcome barriers, improve safety and begin a new era of contemporary wildlife management that embraces PIs. We then provide a framework that supports an objective comparison of intervention suitability, including PIs. We find numerous directions for PI optimisation through innovation and transdisciplinary collaboration and demonstrate the utility of the framework for judging the appropriateness of a PI. Synthesis and applications: Interrogating how and when pharmacological interventions can be used to the greatest effect reduces risks and improves outcomes for wildlife, while empowering decision makers to draw from the full suite of intervention methods to find the most appropriate disease management solutions.

Fifty Years of Wildlife Diseases in Europe: A Citation Database Meta-Analysis.

Although wildlife has progressively been recognized as a booster for the spillover of pathogens to humans and other wild and domestic animals, the interest of scientists in this topic has not been constant over time and uniform in its targets. Epidemiological outbreaks and technological development have contributed to this. Through the analysis of the number of publications from a citation database, we aimed to obtain an indicator of the scientific community's interest towards wildlife diseases over the years. Using Web of Science, bibliographic searches were performed by adding to the basic search string "Wildlife AND Disease" terms detailing topics such as aspect investigated, pathogen type, aetiologic group and species group. For each host species group, the 100 most frequent Medical Subject Headings (MeSHs) related to specific diseases in each decade were extracted. The scientific production regarding wildlife diseases has increased 3.7 times the relative proportion of publications on diseases during the last 50 years, focusing mainly on zoonotic or epizootic pathogens, and with a sharp growth in contemporary hot topics. Wildlife disease scenarios are complex and challenging to approach. Knowing the trends in the scientific interest in the past decades may pose a guide to direct future steps and actions in several fields, from public health to ecosystem management.

Tracking wildlife diseases using community science: an example through toad myiasis

Parasite and pathogen surveillance is crucial for understanding trends in their distributions and host spectra, as well as to document changes in their population dynamics. Nevertheless, continuous surveillance is time-consuming, underfunded due to the non-charismatic nature of parasites/pathogens, and research infrastructure is usually limited to short-term surveillance efforts. Species observation data provided by the public can contribute to long-term surveillance of parasites using photographic evidence of infections shared on community science platforms. Here, we used public photo repositories to document the occurrence across space and time of Lucilia spp. (Diptera: Calliphoridae), a parasite inducing nasal toad myiasis in the European toad Bufo bufo (Anura: Bufonidae). We found a total of 262 toad myiasis observations on iNaturalist (n = 132), on GBIF (n = 86), on Flickr (n = 41), and on observation.org (n = 3). Our results indicate that the distribution of toad myiasis is regionally limited, despite its host being widely distributed and abundant across a wide region in Europe. Observations were found in 12 countries with relatively low prevalence, including Belgium (3.90%, CI 2.44–6.18), Denmark (1.26%, CI 0.89–1.80), France (0.45%, CI 0.14–1.38), Germany (1.27%, CI 0.92–1.75), Lithuania (0.50%, CI 0.13–1.98), Luxembourg (1.30%, CI 0.42–3.95), the Netherlands (2.71%, CI 1.61–4.52), Poland (0.89%, CI 0.34–2.35), Russia (Kaliningrad Oblast) (4.76%, CI 0.67–27.14), Switzerland (NA), Ukraine (0.87%, CI 0.12–5.91), and in the UK (0.45%, CI 0.28–0.72). Nevertheless, the number of uploaded observations of both parasite infection and host presence indicates a stable increase likely due to the growing popularity of community science websites. Overall, community science is a useful tool to detect and monitor certain wildlife diseases and to recognize potential changes in disease dynamics through time and space.

Bacterial Skin Assemblages of Sympatric Salamanders Are Primarily Shaped by Host Genus.

Bacterial assemblages on the skins of amphibians are known to influence pathogen resistance and other important physiological functions in the host. Host-specific factors and the environment play significant roles in structuring skin assemblages. This study used high-throughput 16S rRNA sequencing and multivariate analyses to examine differences in skin-bacterial assemblages from 246 salamanders belonging to three genera in the lungless family Plethodontidae along multiple spatial gradients. Composition and α- and β-diversity of bacterial assemblages were defined, indicator species were identified for each host group, and the relative influences of host- versus environment-specific ecological factors were evaluated. At the broadest spatial scale, host genus, host species, and sampling site were predictive of skin assemblage structure, but host genus and species were more influential after controlling for the marginal effects of site, as well as nestedness of site. Furthermore, assemblage similarity within each host genus did not change with increasing geographic distance. At the smallest spatial scale, site-specific climate analyses revealed different relationships to climatic variables for each of the three genera, and these relationships were determined by host ecomode. Variation in bacterial assemblages of terrestrial hosts correlated with landscape-level climatic variability, and this pattern decayed with increasing water dependence of the host. Results from this study highlight host-specific considerations for researchers studying wildlife diseases in co-occurring, yet ecologically divergent, species.

Best genome sequencing strategies for annotation of complex immune gene families in wildlife.

The biodiversity crisis and increasing impact of wildlife disease on animal and human health provides impetus for studying immune genes in wildlife. Despite the recent boom in genomes for wildlife species, immune genes are poorly annotated in nonmodel species owing to their high level of polymorphism and complex genomic organisation. Our research over the past decade and a half on Tasmanian devils and koalas highlights the importance of genomics and accurate immune annotations to investigate disease in wildlife. Given this, we have increasingly been asked the minimum levels of genome quality required to effectively annotate immune genes in order to study immunogenetic diversity. Here we set out to answer this question by manually annotating immune genes in 5 marsupial genomes and 1 monotreme genome to determine the impact of sequencing data type, assembly quality, and automated annotation on accurate immune annotation. Genome quality is directly linked to our ability to annotate complex immune gene families, with long reads and scaffolding technologies required to reassemble immune gene clusters and elucidate evolution, organisation, and true gene content of the immune repertoire. Draft-quality genomes generated from short reads with HiC or 10× Chromium linked reads were unable to achieve this. Despite mammalian BUSCOv5 scores of up to 94.1% amongst the 6 genomes, automated annotation pipelines incorrectly annotated up to 59% of manually annotated immune genes regardless of assembly quality or method of automated annotation. Our results demonstrate that long reads and scaffolding technologies, alongside manual annotation, are required to accurately study the immune gene repertoire of wildlife species.

Sarcoptic mange is an emerging threat to biodiversity in the Qinling Mountains in China.

Sarcoptic mange, a disease caused by the burrowing mite Sarcoptes scabiei, is globally endemic and an emerging threat to wildlife. Although many studies have shown that wildlife diseases play key roles in biodiversity conservation, knowledge about sarcoptic mange is still insufficient. In this study, we aim to improve the understanding of the impacts of sarcoptic mange on wildlife populations, the mechanisms involved in its eco-epidemiology and the associated risks to public and ecosystem health by investigating mass death events in gorals and serows in the Qinling Mountains. We conducted interviews with practitioners and local people in the central Qinling Mountains. From the same locations, we collected 24 cutaneous samples from various animals and surveillance data from infrared cameras. Pathological, parasitological and microbiological examinations of the samples were performed. Mite-induced cutaneous lesions, mites and eggs were observed in samples from dead gorals and one dead serow but not in other species. Molecular analysis confirmed the mites to be S. scabiei and shared the same cox 1 genotype. The data obtained from the interviews and infrared cameras indicated that the death of wildlife was related to sarcoptic mange infection and that there had been a decrease in the goral population since the outbreak of the disease. We confirmed that sarcoptic mange was the major cause of the mass death events and may have spread from the western to eastern Qinling Mountains. Based on our findings, we propose several protection strategies to help preserve biodiversity in the Qinling Mountains.