The importance of long-term studies on wildlife diseases and their interfaces with humans and domestic animals: A review

Fibropapillomatosis Dynamics, Severity and Demographic Effect in Caribbean Green Turtles

Habitat degradation induced by human activities can exacerbate the spread of wildlife disease and could hinder the recovery of imperiled species. The endangered green turtle Chelonia mydas is impacted worldwide by fibropapillomatosis (FP), a neoplastic infectious disease likely triggered by the Scutavirus chelonidalpha5 with coastal anthropogenic stressors acting as cofactors in disease development. Here, we studied fibropapillomatosis dynamics and its demographic consequences using an 11-year capture-mark-recapture dataset in Anse du Bourg d'Arlet/Chaudière (ABAC) and Grande Anse d'Arlet (GA), two juvenile green turtle foraging grounds in Martinique, French West Indies. Afflicted turtles had similar mortality and permanent emigration rates to the non-afflicted ones. Fibropapillomatosis was commonly observed in large individuals and disease recovery may take several years. Consequently, permanent emigration before full recovery from the disease is suspected and might affect the developmental migration success. Additionally, the results revealed that the FP had higher prevalence and severity, and progressed two times faster in ABAC than in GA despite the proximity (< 2 km) and the similarity of the two foraging grounds. The reasons for these differences remain unidentified. Locally, further studies should be focused on the determination of the external and internal cofactors related to the observed FP dynamics. Finally, the investigations should be extended at a global regional scale to determine potential deleterious effect of the FP on the adult life-stage. These perspectives improves upon our overall understanding on the interplay between wildlife diseases, hosts and environmental factors.

Early Detection of Wildlife Disease Pathogens Using CRISPR-Cas System Methods

Wildlife diseases are a considerable threat to human health, conservation, and the economy. Surveillance is a critical component to mitigate the impact of animal diseases in these sectors. To monitor human diseases, CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated protein) biosensors have proven instrumental as diagnostic tools capable of detecting unique DNA and RNA sequences related to their associated pathogens. However, despite the significant advances in the general development of CRISPR-Cas biosensors, their use to support wildlife disease management is lagging. In some cases, wildlife diseases of concern could be rapidly surveyed using these tools with minimal technical, operational, or cost requirements to end users. This review explores the potential to further leverage this technology to advance wildlife disease monitoring and highlights how concerted standardization of protocols can help to ensure data reliability.

May Artificial Intelligence take health and sustainability on a honeymoon? Towards green technologies for multidimensional health and environmental justice

The application of Artificial Intelligence (AI) in healthcare and epidemiology undoubtedly has many benefits for the population. However, due to its environmental impact, the use of AI can produce social inequalities and long-term environmental damages that may not be thoroughly contemplated. In this paper, we propose to consider the impacts of AI applications in medical care from the One Health paradigm and long-term global health. From health and environmental justice, rather than settling for a short and fleeting green honeymoon between health and sustainability caused by AI, it should aim for a lasting marriage. To this end, we conclude by proposing that, in the upcoming years, it could be valuable and necessary to promote more interconnected health, call for environmental cost transparency, and increase green responsibility. Highlights Using AI in medicine and epidemiology has some benefits in the short term.AI usage may cause social inequalities and environmental damage in the long term.Health justice should be rethought from the One Health perspective.Going beyond anthropocentric and myopic cost-benefit analysis would expand health justice to include an environmental dimension.Greening AI would help to reconcile public and global health measures.

High Exposure to Livestock Pathogens in Southern Pudu (Pudu puda) from Chile

A significant gap in exposure data for most livestock and zoonotic pathogens is common for several Latin America deer species. This study examined the seroprevalence against 13 pathogens in 164 wild and captive southern pudu from Chile between 2011 and 2023. Livestock and zoonotic pathogen antibodies were detected in 22 of 109 wild pudus (20.18%; 95% CI: 13.34-29.18) and 17 of 55 captive pudus (30.91%; 95% CI: 19.52-44.96), including five Leptospira interrogans serovars (15.38% and 10.71%), Toxoplasma gondii (8.57% and 37.50%), Chlamydia abortus (3.03% and 12.82%), Neospora caninum (0.00% and 9.52%), and Pestivirus (8.00% and 6.67%). Risk factors were detected for Leptospira spp., showing that fawn pudu have statistically significantly higher risk of positivity than adults. In the case of T. gondii, pudu living in "free-range" have a lower risk of being positive for this parasite. In under-human-care pudu, a Pestivirus outbreak is the most strongly suspected as the cause of abortions in a zoo in the past. This study presents the first evidence of Chlamydia abortus in wildlife in South America and exposure to T. gondii, L. interrogans, and N. caninum in wild ungulate species in Chile. High seroprevalence of livestock pathogens such as Pestivirus and Leptospira Hardjo in wild animals suggests a livestock transmission in Chilean template forest.

Genetic mechanisms and biological processes underlying host response to ophidiomycosis (snake fungal disease) inferred from tissue-specific transcriptome analyses

Emerging infectious diseases in wildlife species caused by pathogenic fungi are of growing concern, yet crucial knowledge gaps remain for diseases with potentially large impacts. For example, there is detailed knowledge about host pathology and mechanisms underlying response for chytridiomycosis in amphibians and white-nose syndrome in bats, but such information is lacking for other more recently described fungal infections. One such disease is ophidiomycosis, caused by the fungus Ophidiomyces ophidiicola, which has been identified in many species of snakes, yet the biological mechanisms and molecular changes occurring during infection are unknown. To gain this information, we performed a controlled experimental infection in captive Prairie rattlesnakes (Crotalus viridis) with O. ophidiicola at two different temperatures: 20 and 26°C. We then compared liver, kidney, and skin transcriptomes to assess tissue-specific genetic responses to O. ophidiicola infection. Given previous histopathological studies and the fact that snakes are ectotherms, we expected highest fungal activity on skin and a significant impact of temperature on host response. Although we found fungal activity to be localized on skin, most of the differential gene expression occurred in internal tissues. Infected snakes at the lower temperature had the highest host mortality whereas two-thirds of the infected snakes at the higher temperature survived. Our results suggest that ophidiomycosis is likely a systemic disease with long-term effects on host response. Our analysis also identified candidate protein coding genes that are potentially involved in host response, providing genetic tools for studies of host response to ophidiomycosis in natural populations.

Molecular survey and phylogenetic analysis of Bartonella sp., Coxiella sp., and hemoplamas in pudu (Pudu puda) from Chile: first report of Bartonella henselae in a wild ungulate species

Introduction

Recent evidence shows a high diversity of infectious agents in wildlife that represent a threat to human, domestic, and wild animal health. In Chile, wild populations of the most common cervid species, pudu (Pudu puda), have been reported as hosts for novel pathogens such as Mycoplasma ovis-like and a novel ecotype of Anaplasma phagocytophilum. A better understanding of the epidemiology of this group and other intracellular bacteria that might have cervids as hosts would enlighten their population relevance. This study aimed to determine the occurrence and genetic diversity of Bartonella spp., hemotropic mycoplasmas, and Coxiella burnetii in pudus from Chile.

Methods

The DNA was extracted from the blood samples of 69 wild free-ranging and 30 captive pudus from Chile. A combination of real-time (nouG gene for Bartonella and IS1111 element for C. burnetii) and conventional PCR (16S rRNA for hemotropic Mycoplasma spp. and rpoB, gltA, and ITS for Bartonella spp.) was used for pathogen screening and molecular characterization.

Results

DNA of Bartonella spp. was detected in 10.1% [95% CI (5.2-18.2%)] samples, hemotropic Mycoplasma spp. in 1.7% [95% CI (0.08-10.1%)], and C. burnetii in 1.0% [95% CI (0.05-6.3%)] samples. Two sequenced samples were identified as Mycoplasma ovis-like, and one free-ranging pudu was positive for C. burnetii. While one captive and two free-ranging pudus were positive for Bartonella henselae, one wild pudu was co-positive for B. henselae and Bartonella sp., similar to Bartonellae identified in ruminants.

Discussion

To the best of our knowledge, this is the first report of B. henselae in wild ungulate species, and C. burnetii and Bartonella spp. in wild ungulate species in South America. Further research will be necessary to evaluate the potential role of pudu as reservoirs of infection and identify the sources for disease transmission among humans and wild and domestic animals.

Comparative analysis of gut DNA viromes in wild and captive Himalayan vultures

Introduction

Himalayan vultures (Gyps hinalayensis) are widely distributed on the Qinghai-Tibetan Plateau and play a crucial role in maintaining the ecological balance by feeding on decayed corpses of wild and domestic animals. Large-scale culture and metagenomics studies have broadened our understanding of viral diversity in animals' gastrointestinal tracts. However, despite the importance of gut viral communities in regulating bacterial diversity and performing symbiotic functions, no gut viral study has been conducted on Himalayan vultures. Furthermore, the impact of captivity on the gut virome of these vultures remains unknown.

Methods

In this study, metagenomic sequencing methods targeting DNA of virus-like particles enriched from feces were used to characterize the gut DNA viromes of wild and captive Himalayan vultures.

Results

In total, 22,938 unique viral operational taxonomic units (vOTUs) were identified and assigned to 140 viral genera in 41 viral families. These families included viruses associated with bacteria, animals, plants, insects, and archaea. Phage communities, including Siphoviridae, Microviridae, Myoviridae, Inoviridae, and Herelleviridae, dominated the gut virome of Himalayan vultures. Wild vultures exhibited higher viral richness and diversity compared with those in captivity. The functional capacity of the gut virome was characterized by identifying 93 KEGG pathways, which were significantly enriched in metabolism and genetic information processing. Abundant auxiliary metabolic genes, such as carbohydrate-active enzyme, and antibiotic resistance genes, were also found in the vultures' gut virome.

Discussion

Our findings reveal the complex and diverse viral community present in the gut virome of Himalayan vultures, which varies between wild, and captive states. The DNA virome dataset establishes a baseline for the vultures' gut virome and will serve as a reference for future virus isolation and cultivation. Understanding the impact of captivity on the gut virome contributes to our knowledge of vultures' response to captivity and aids in optimizing their rehabilitation and implementing protective measures.

The heterogeneous herd: Drivers of close-contact variation in African buffalo and implications for pathogen invasion

Many infectious pathogens are shared through social interactions, and examining host connectivity has offered valuable insights for understanding patterns of pathogen transmission across wildlife species. African buffalo are social ungulates and important reservoirs of directly-transmitted pathogens that impact numerous wildlife and livestock species. Here, we analyzed African buffalo social networks to quantify variation in close contacts, examined drivers of contact heterogeneity, and investigated how the observed contact patterns affect pathogen invasion likelihoods for a wild social ungulate. We collected continuous association data using proximity collars and sampled host traits approximately every 2 months during a 15-month study period in Kruger National Park, South Africa. Although the observed herd was well connected, with most individuals contacting each other during each bimonthly interval, our analyses revealed striking heterogeneity in close-contact associations among herd members. Network analysis showed that individual connectivity was stable over time and that individual age, sex, reproductive status, and pairwise genetic relatedness were important predictors of buffalo connectivity. Calves were the most connected members of the herd, and adult males were the least connected. These findings highlight the role susceptible calves may play in the transmission of pathogens within the herd. We also demonstrate that, at time scales relevant to infectious pathogens found in nature, the observed level of connectivity affects pathogen invasion likelihoods for a wide range of infectious periods and transmissibilities. Ultimately, our study identifies key predictors of social connectivity in a social ungulate and illustrates how contact heterogeneity, even within a highly connected herd, can shape pathogen invasion likelihoods.

Drone-Based Thermal Imaging in the Detection of Wildlife Carcasses and Disease Management

Because animal carcasses often serve as reservoirs for pathogens, their location and removal are crucial in controlling the spread of diseases. During carcass decomposition, heat is emitted due to microbial activity and the development of maggots. Recent studies have shown that infrared sensors can be used to locate animal carcasses, but little is known about the factors influencing detection success. In this study, we investigated the potential of infrared technology to locate wild boar carcasses, as they play an important role in the spread of African swine fever. Specifically, we tested the effects of environmental and carcass conditions on the detection probability. A drone-based thermal camera was used to collect data during 379 flyovers of 42 wild boar carcasses in different stages of decomposition between September 2020 and July 2021. Generalized mixed-effect models and conditional inference trees were used to identify the environmental and carcass conditions that influenced the detection probability. Our results showed that the thermal camera accurately measured carcass temperature (R 2 = 0.75, RMSE = 5.89°C). The probability of finding carcasses was higher in open habitats with air temperatures >3.0°C and thus conducive to maggot development (detection rate ≤80%). A forest canopy openness >29.3% and cloudy conditions or flights at dawn increased the detection rate. Moreover, carcasses infested with large amounts of maggots could be detected even in habitats with a more extensive canopy cover, whereas in dense forests, the detection probability was limited (<25%). Carcasses in an advanced stage of decomposition could still be detected as long as the difference between the carcass temperature and the air temperature was >6.4°C (≤62%). Our study demonstrates the utility of thermal imaging in searching for wild boar carcasses under specific environmental and carcass conditions and thus its use in supporting ground searches.

Attitudes of Young Tri-City Residents toward Game Meat in the Context of Food Neophobia and a Tendency to Look for Diversity in Food

To conduct rational hunting management, a certain number of wild animals must be harvested yearly. However, some countries have a problem with managing the harvested meat. An example is Poland, where game consumption is estimated at 0.08 kg/person/year. This situation leads to environmental pollution as a result of meat exports. The level of environmental pollution depends on the type of transport and distance. However, the use of meat in the country of harvesting would generate less pollution than its export. Three constructs were used in the study, which aimed to determine whether the respondents show food neophobia, whether they are willing to seek diversity in food, and what their attitudes towards game meat are. All the scales used were previously validated. Four-hundred and fifty-three questionnaires were collected using the PAPI method. It was found that the respondents showed ambivalent attitudes towards game meat to the greatest extent (76.6%), 16.34% had positive attitudes, and 7.06% had negative attitudes. It seems essential that most of the respondents were highly inclined to look for variety in food (55.85%). Regarding food neophobia, there were 51.43% of people with medium neophobia, while also many people with a low level of neophobia-43.05%. Such results allow speculation that the respondents are open to the new food, they are looking for it, and the low level of game meat consumption is primarily due to the lack of knowledge and awareness about the value of this meat.

Using integrated wildlife monitoring to prevent future pandemics through one health approach

In the One Health context, Integrated Wildlife Monitoring (IWM) merges wildlife health monitoring (WHM) and host community monitoring to early detect emerging infections, record changes in disease dynamics, and assess the impact of interventions in complex multi-host and multi-pathogen networks. This study reports the deployment and results obtained from a nationwide IWM pilot test in eleven sites representing the habitat diversity of mainland Spain. In each study site, camera-trap networks and sampling of indicator species for antibody and biomarker analysis were used to generate information. The results allowed identifying differences in biodiversity and host community characteristics among the study sites, with a range of 8 to 19 relevant host species per point. The Eurasian wild boar (Sus scrofa) was the most connected and central species of the host communities, becoming a key target indicator species for IWM. A negative relationship between biodiversity and disease risk was detected, with a lower number and prevalence of circulating pathogens in the sites with more species in the community and larger network size. However, this overall trend was modified by specific host-community and environmental factors, such as the relative index of wild boar - red deer interactions or the proximity to urban habitats, suggesting that human-driven imbalances may favour pathogen circulation. The effort of incorporating wildlife population monitoring into the currently applied WHM programs to achieve effective IWM was also evaluated, allowing to identify population monitoring as the most time-consuming component, which should be improved in the future. This first nationwide application of IWM allowed to detect drivers and hotspots for disease transmission risk among wildlife, domestic animals, and humans, as well as identifying key target indicator species for monitoring. Moreover, anthropogenic effects such as artificially high wildlife densities and urbanisation were identified as risk factors for disease prevalence and interspecific transmission.

Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep

Monitoring the prevalence and abundance of parasites over time is important for addressing their potential impact on host life histories, immunological profiles and their influence as a selective force. Only long-term ecological studies have the potential to shed light on both the temporal trends in infection prevalence and abundance and the drivers of such trends, because of their ability to dissect drivers that may be confounded over shorter time scales. Despite this, only a relatively small number of such studies exist. Here, we analysed changes in the prevalence and abundance of gastrointestinal parasites in the wild Soay sheep population of St. Kilda across 31 years. The host population density (PD) has increased across the study, and PD is known to increase parasite transmission, but we found that PD and year explained temporal variation in parasite prevalence and abundance independently. Prevalence of both strongyle nematodes and coccidian microparasites increased during the study, and this effect varied between lambs, yearlings and adults. Meanwhile, abundance of strongyles was more strongly linked to host PD than to temporal (yearly) dynamics, while abundance of coccidia showed a strong temporal trend without any influence of PD. Strikingly, coccidian abundance increased 3-fold across the course of the study in lambs, while increases in yearlings and adults were negligible. Our decades-long, intensive, individual-based study will enable the role of environmental change and selection pressures in driving these dynamics to be determined, potentially providing unparalleled insight into the drivers of temporal variation in parasite dynamics in the wild.

Spatiotemporal monitoring of myxomatosis in European wild rabbit (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems

A long-term active epidemiological surveillance programme was conducted to determine seroprevalence to myxoma virus (MYXV), infection prevalence and spatiotemporal patterns and factors associated with MYXV circulation in wild rabbits (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems. A total of 2376 animals were sampled over four study periods: 2009-2012 (P1), 2012-2015 (P2), 2015-2018 (P3) and 2018-2021 (P4). Antibodies against MYXV were detected by a commercial indirect ELISA in 59.9% (1424/2376; 95% CI: 58.0-61.9) of wild rabbits. At least one seropositive animal was detected on 131 (96.3%) of 136 game estates sampled. MYXV infection was confirmed by PCR in 94 of 1063 (8.8%; 95% CI: 7.3-10.7) wild rabbits. Circulation of the novel recombinant MYXV (ha-MYXV) was not found in wild rabbits analysed during P4. Five statistically significant spatiotemporal clusters of high MYXV seroprevalence were identified using a Bernoulli model: one in P2 and four in P3. A generalized linear mixed model (GLMM) analysis identified sampling season (autumn), age (adult and juvenile), outbreaks of myxomatosis in the month prior to sampling, mean annual temperature, humidity and seropositivity to rabbit haemorrhagic disease virus as factors potentially linked with MYXV seropositivity. GLMM analysis identified outbreaks of myxomatosis in the month prior to sampling, MYXV seropositivity and presence of lesions compatible with myxomatosis as factors associated with MYXV infection. The results indicate high exposure, widespread but non-homogeneous distribution, and endemic circulation of MYXV in wild rabbit populations in southern Spain during the last decade. Prevalence of antibodies against MYXV showed fluctuations both within the year and over the study periods, revealing variations in the immunity of wild rabbit populations in Mediterranean ecosystems that could increase the risk of MYXV re-emergence in immunologically naïve populations. The present study highlights the importance of long-term surveillance to better understand the epidemiology of MYXV in wild lagomorphs.

First Detection of Salmonella enterica Serovar Choleraesuis in Free Ranging European Wild Boar in Sweden

Following the first detection of Salmonella enterica subsp. enterica, serovar Choleraesuis (S. Choleraesuis) in a Swedish pig herd for more than 40 years and subsequent detection of the same serotype in an enclosure with kept wild boar, a national surveillance for S. Choleraesuis in free living wild boar was launched. A total of 633 wild boar sampled within the active and the enhanced passive surveillance were examined for Salmonella enterica serovars by culture. Of these, 80 animals were culture positive for S. Choleraesuis var. Kunzendorf. All positive animals, including those in the original outbreaks, originated from counties located in the southern and eastern parts of Sweden. Fifty-eight isolates were selected for sequence typing, revealing a relatively homogenous population of S. Choleraesuis with two distinct genetic clusters containing isolates from the southern counties in one and the counties further northeast in the other. Sequenced isolates from domestic pig farms all clustered with wild boar in the same region. S. Choleraesuis appears highly contagious in dense wild boar populations, making it a relevant model for other infectious diseases that may be transmitted to pigs. The many potential routes of introduction and spread of S. Choleraesuis warrant further investigations in order to prepare for other disease threats.

Survey of Culicoides-borne Bluetongue and Schmallenberg viruses at the wildlife-livestock interface in Doñana National Park (Spain)

A cross-sectional study was carried out to assess the circulation of bluetongue virus (BTV) and Schmallenberg virus (SBV) within the wild and domestic ungulate host community in Doñana National Park (southwestern Spain). A total of 440 animals, including 138 cattle, 102 red deer (Cervus elaphus), 101 fallow deer (Dama dama) and 99 wild boar (Sus scrofa) were sampled in 2015 during the seasonal peak of Culicoides spp. (summer-autumn). Serum and spleen samples were analysed to detect exposure (using commercial blocking ELISAs) and infection (by RT-PCR), respectively, to BTV and SBV. Cattle were not tested by BTV-bELISA because all were previously vaccinated against BTV serotypes 1 and 4. High BTV seroprevalences were found in red deer (97.0%) and fallow deer (64.7%). Antibodies against SBV were detected in 37.0% of cattle, 16.8% of red deer, 23.5% of fallow deer and 2.0% of wild boar. Thirty-eight of the 203 deer (18.7%; 17 red deer and 21 fallow deer) were co-exposed to both viral agents. BTV-4 RNA was confirmed in four red deer and two fallow deer. SBV RNA was found in two fallow deer. Co-infections were not detected. Our results indicate high exposure, widespread distribution, and active circulation of BTV and SBV in the ruminant community in the study area. We provide additional evidence for the potential role of wild cervids as reservoirs of these Culicoides-borne viruses in two different epidemiological scenarios: with vaccination (BTV) and without vaccination (SBV) of sympatric livestock. This study highlights the importance of wildlife surveillance, particularly of cervid species, for the proper execution of control programmes of Culicoides-borne diseases in extensively reared livestock. This article is protected by copyright. All rights reserved.

Long-Term Determinants of the Seroprevalence of the Hepatitis E Virus in Wild Boar (Sus scrofa)

Simple Summary

The hepatitis E virus (HEV) is an emerging multi-host pathogen whose main reservoir is suids, and the leading cause of acute viral hepatitis in humans. This study evaluates the main long-term drivers of the exposure to HEV are in the wild boar population from Doñana National Park (southwestern Spain) during a 13-year period (2005–2018). For this purpose, we assay sera from 700 wild boar in which anti-HEV antibodies are widely distributed (46.7 ± 3.8%, 327 out of 700 sampled). The observed marked interannual fluctuations could be explained by the variations in the population control of the wild boar during the study period and its impact on abundance rates. Several factors operating in the medium and long-term (individual, environmental, populational and stochastic) and their interplay explained the exposure to HEV in wild boar. The preferential use of certain areas by wild boar together with its abundance and the meteorological conditions may be behind the level of exposure. Wild boar population control remains a challenge at the international level, and an increase of shared pathogen-related conflicts associated with this species is expected, as exemplified by HEV.

Abstract

The hepatitis E virus (HEV) is an emerging zoonotic pathogen whose main reservoir is suids. Most of the ecological and epidemiological aspects of its sylvatic cycle remain unknown. Thus, in this work, we study the drivers of HEV exposure in the wild boar population of Doñana National Park (DNP, southwest Spain) operating in the medium and long-term (2005–2018). Anti-HEV antibodies are widely distributed throughout the wild boar (46.7 ± 3.8%, 327 out of 700 sampled), showing a statistically significant age-increasing pattern. The temporal pattern displayed important interannual fluctuations. This could be mediated by marked variations in the population control of the wild boar, and subsequent changes in abundance rates, and its interplay with climatic conditions; as wet years together with a low abundance of wild boar led to the lowest seroprevalence. The fact that seroprevalence is high during conditions of high abundance, and not affected by rainfall level, is probably due to the increased interactions among the animals, and possibly, the subsequent higher environmental contamination with HEV particles. The proximity to the marshland (the main water body of the study area) is associated with a higher risk of testing positive, which is probably mediated by the preferential use of this area during the dry season and the favourable environmental conditions for the survival of HEV particles. A deeper understanding of the epidemiology of HEV in host communities deserves future research concerning other susceptible species. Most importantly, wild boar population control remains a challenge at the international level, and an increase of shared pathogen-related conflicts associated with this species is expected, as exemplified by HEV. Therefore, surveillance of wild boar diseases, including integrated population monitoring and sustainable population control programmes, will be essential to control the associated risks.

The role of social structure and dynamics in the maintenance of endemic disease

Social interactions are required for the direct transmission of infectious diseases. Consequently, the social network structure of populations plays a key role in shaping infectious disease dynamics. A huge research effort has examined how specific social network structures make populations more (or less) vulnerable to damaging epidemics. However, it can be just as important to understand how social networks can contribute to endemic disease dynamics, in which pathogens are maintained at stable levels for prolonged periods of time. Hosts that can maintain endemic disease may serve as keystone hosts for multi-host pathogens within an ecological community, and also have greater potential to act as key wildlife reservoirs of agricultural and zoonotic diseases. Here, we examine combinations of social and demographic processes that can foster endemic disease in hosts. We synthesise theoretical and empirical work to demonstrate the importance of both social structure and social dynamics in maintaining endemic disease. We also highlight the importance of distinguishing between the local and global persistence of infection and reveal how different social processes drive variation in the scale at which infectious diseases appear endemic. Our synthesis provides a framework by which to understand how sociality contributes to the long-term maintenance of infectious disease in wildlife hosts and provides a set of tools to unpick the social and demographic mechanisms involved in any given host-pathogen system.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00265-021-03055-8.

Long-Term Determinants of the Seroprevalence of Toxoplasma gondii in a Wild Ungulate Community

Toxoplasma gondii is an obligate intracellular protozoan which infects warm-blooded vertebrates, including humans, worldwide. In the present study, the epidemiology of T. gondii was studied in the wild ungulate host community (wild boar, red deer, and fallow deer) of Doñana National Park (DNP, south-western Spain) for 13 years (2005-2018). We assessed several variables which potentially operate in the medium and long-term (environmental features, population, and stochastic factors). Overall, the wild ungulate host community of DNP had high seroprevalence values of T. gondii (STG; % ± confidence interval (CI) 95%; wild boar (Sus scrofa) 39 ± 3.3, n = 698; red deer (Cervus elaphus) 30.7 ± 4.4, n = 423; fallow deer (Dama dama) 29.7 ± 4.2, n = 452). The complex interplay of hosts and ecological/epidemiological niches, together with the optimal climatic conditions for the survival of oocysts that converge in this area may favor the spread of the parasite in its host community. The temporal evolution of STG oscillated considerably, mostly in deer species. The relationships shown by statistical models indicated that several factors determined species patterns. Concomitance of effects among species, indicated that relevant drivers of risk operated at the community level. Our focus, addressing factors operating at broad temporal scale, allows showing their impacts on the epidemiology of T. gondii and its trends. This approach is key to understanding the epidemiology and ecology to T. gondii infection in wild host communities in a context where the decline in seroprevalence leads to loss of immunity in humans.