Cross-species transmission of retroviruses among domestic and wild felids in human-occupied landscapes in Chile

Influence of Host and Landscape-Associated Factors in the Infection and Transmission of Pathogens: The Case of Directly Transmitted Virus in Mammals

BACKGROUND

Among pathogens associated with mammals, numerous viruses with a direct transmission route impact human, domestic and wild species health. Host and landscape factors affect viral infection and transmission dynamics of these viruses, along with barriers to host dispersal and gene exchange. However, studies show biases toward certain locations, hosts and detected pathogens, with regional variations in similar host-virus associations.

METHODS

Using a systematic review, in two electronic repositories for articles published until December 2022, we analysed the available information on host- and landscape-associated factors influencing the infection and transmission of directly transmitted viruses in mammals.

RESULTS

In the analysis, about 50% of papers examined either host traits, landscape composition or configuration measures, while approximately 24% combined host and landscape-associated factors. Additionally, approximately 17% of the articles included climatic data and 30% integrated factors related to anthropogenic impact, as these variables have a role in host density, distribution and virus persistence. The most significant and frequent host traits used as predictor variables were sex, age, body weight, host density and species identity. Land cover was the most evaluated landscape attribute, while some explored configuration variables like edge density and fragmentation indexes. Finally, temperature, precipitation and features such as human population density and human footprint index were also typically measured and found impactful.

CONCLUSION

Given the many contributions host- and landscape-related factors have in pathogen dynamics, this systematic study contributes to a better knowledge of host-virus dynamics and the identification of variables and gaps that can be used for disease prevention.

High prevalence and risk factors of feline leukemia virus infection in Chilean urban cats (Felis catus)

Feline Leukemia Virus is a retrovirus causing fatal disease in domestic cats. While FeLV has been controlled in many countries, it remains a major concern in Latin American countries. This study conducted an epidemiological survey of FeLV in 182 Chilean domestic cats using PCR to detect provirus infection. The results were analysed using Multivariate Logistic Regression to examine risk factors associated with FeLV detection. The FeLV prevalence was 54.95 %, and statistically significant associations (p < 0.05) were found for two protective factors and one risk factor. Cats from Concepcion city (95 %CI 0.08-0.56 %) and cats sampled in 2022 (95 %CI 0.1-0.06 %) had lower odds ratios for provirus positivity, whereas non-vaccinated cats (95 %CI 2.3-15.8 %) had an increased odds ratio. No other factors were statistically significant. The high FeLV prevalence is similar to other Latin American countries and the geographical differences highlighted in this study likely correspond to the socioeconomic status of the owners. This study highlights the need for improved FeLV control measures such as promoting FeLV vaccination, implementing health screening prior to adoption of new cats, and educating owners about FeLV to control its circulation.

Global seroprevalence and factors associated with seropositivity for feline immunodeficiency virus (FIV) in cats: A systematic review and meta-analysis

The feline immunodeficiency virus (FIV) is a retrovirus of the Lentivirus genus, distributed worldwide, that causes persistent infection with a significant impact on the cats' health. Due to the importance of this infection in feline medicine, this pioneering study aimed to obtain an integrated estimate of the global seroprevalence of FIV in cats and to characterize the factors associated with this infection. Four electronic databases were screened for observational studies with FIV seroprevalence in cats published globally for this systematic review and meta-analysis. The initial search method returned 873 studies, of which 113 met all predefined criteria and were therefore included in this review. Meta-analysis with general data was performed, and a combined global seropositivity of 9.43 % (95 % CI: 8.24 % - 10.78 %) was found. Seropositivity was 14.34 % (95 % CI = 10.92 % - 18.61 %) in Asia, 11.90 % (95 % CI = 9.82 % - 14.34 %) in Oceania, 10.90 % (95 % CI = 5.71 % - 19.82 %) in Central America, 9.43 % (95 % CI = 6.95 % - 12.66 %) in South America, 9 % (95 % CI = 0 - 80 %) in Africa, 8.98 % (95 % CI = 7.31 % - 10.98 %) in Europe, and 5.93 % (95 % CI = 4.33 % - 8.07 %) in North America. Meta-analysis of factors associated with seropositivity demonstrated that FIV seroprevalence was higher in male (Prevalence ratio [PR] = 2.53, 95 % CI = 2.16 - 2.95), adult (PR = 2.83, 95 % CI = 2.24 - 3.56), unowned status (PR = 1.47, 95 % CI = 1.07 - 2.03), sick status (PR = 2.46, 95 % CI = 1.97 - 3.06), and cats with outdoor access (PR = 4.38, 95 % CI = 2.26 - 8.47). The results demonstrated that FIV is globally distributed and has a high seroprevalence in some geographical areas. Information compiled from this research is relevant to understanding the worldwide epidemiology of FIV. It presents the potential to contribute to the planning of strategies focused on controlling and reducing cases in cat populations.

Epidemiological survey of infectious agents in free-ranging maned wolves (Chrysocyon brachyurus) in Northeastern Brazil

Infectious diseases are one of the most concerning threats to maned wolves (Chrysocyon brachyurus) due to the potential impact on free-ranging populations. The species is currently classified as vulnerable according to the national list of threatened species and occurs mainly in open habitats, such as the Cerrado, a tropical savannah, which comprises its main distribution area in Brazil. In the northeastern region, it occurs in the Cerrado of Bahia, Piauí, Maranhão, and Tocantins states. Therefore, this study aimed to investigate the occurrence of infectious agents in Chrysocyon brachyurus through an epidemiological assessment of free-ranging individuals in western Bahia, specifically in the Barreiras microregion, a Cerrado area intensely fragmented and anthropized by agricultural activity. Eleven specimens were evaluated for serological titration, antigen research, and genetic material research for canine distemper virus (CDV), canine parvovirus (CPV), adenovirus-canine-type 1 (CAdV-1), canine coronavirus (CCoV), Leptospira interrogans and Toxoplasma gondii from 2020 to 2022. In addition to maned wolves, domestic dogs were also evaluated and tested. All maned wolves (100%) evaluated by the dot-ELISA technique exhibited immunoglobulin M (IgM) and seven (64%) exhibited immunoglobulin G (IgG) against CDV and CPV, while 100% exhibited IgG against CDV when using the immunochromatographic technique. Regarding CAdV-1, 90% were seropositive for IgG, while 64% exhibited IgG against T. gondii. Nine dogs from the region were also sampled, and all (100%) exhibited IgM and IgG against CDV and CPV. For IgG against T. gondii and against CAdV-1, 90% of the animals were seropositive. Molecular evaluation yielded negative results for all maned wolves and dogs assessed for CAdV-1, CDV, and T. gondii, as well as the CCoV antigen. These data indicate the occurrence of viral agents and Toxoplasma gondii in maned wolves and dogs, suggesting circulation in both populations.

Occurrence of Typical Domestic Animal Viruses in Wild Carnivorans: An Emerging Threat to the Conservation of Endangered Species

Wild species are susceptible to several typical domestic animal pathogens, and the increasingly close contact between these groups is a predictive factor for disease exposure. Some viruses are important and old-known, and others are emerging or reemerging for domestic carnivorans and have been identified as threats to the conservation of wild mammals. The purpose of the study was to investigate the occurrence of bocaparvoviruses (BoVs, Parvoviridae family, Parvovirinae subfamily, Bocaparvovirus genus), parvoviruses (Parvoviridae family, Parvovirinae subfamily, Protoparvovirus genus, Protoparvovirus carnivoran1), hepadnaviruses (Hepadnaviridae family), coronaviruses (Coronaviridae family, Orthocoronavirinae subfamily), paramyxoviruses (Paramyxoviridae family) and canine distemper virus (Orthoparamyxovirinae subfamily, Morbillivirus genus, Morbillivirus canis), poxviruses (Poxviridae family), feline herpesvirus (Orthoherpesviridae family, Alphaherpesvirinae subfamily, Varicellovirus genus, Varicellovirus felidalpha1), feline calicivirus (Caliciviridae family, Vesivirus genus, FCV), feline immunodeficiency virus (Retroviridae family, Orthoretrovirinae subfamily, Lentivirus genus, FIV), feline leukemia virus (Retroviridae family, Orthoretrovirinae subfamily, Gammaretrovirus genus, FeLV), and gammaherpesviruses (Orthoherpesviridae family, Gammaherpesvirinae subfamily) in wild carnivorans. A total of 30 biological samples from the families Canidae, Felidae, Mephitidae, Mustelidae, and Procyonidae were evaluated. All animals were victims of vehicular collisions in the state of Mato Grosso do Sul, Brazil. Canine parvovirus (CPV-2) DNA was detected in the spleen of a bush dog (Speothos venaticus), a jaguarundi (Puma yagouaroundi), and a jaguar (Panthera onca), FeLV proviral DNA was found in the spleen of an ocelot (Leopardus pardalis); while CDV RNA was detected in the liver of a jaguarundi. Phylogenetic analysis carried out with the partial sequence of the CPV-2 VP2 gene and the U3 (LTR) gag region of FeLV showed 100% identity with strains obtained from domestic dogs and cats, respectively. The approximation between wild and domestic animals favors the transmission of pathogens, especially between phylogenetically close species, such as members of the Canidae and Felidae families. Identification of the DNA and RNA of potentially fatal viruses such as CPV-2, FeLV, and CDV in four wilds endangered to extinction and understudied species contributes to our understanding of the pathogens circulating in this free-ranging and vulnerable population.

Domestic Cat Hepadnavirus and Pathogenic Retroviruses; A Sero-Molecular Survey of Cats in Santiago, Chile

Cat ownership is common in Chile, but data on the regional prevalence of infectious agents are limited. A sero-molecular survey of 120 client- or shelter-owned domestic cats in greater Santiago was performed. Whole blood DNA was tested for the novel hepatitis-B-like virus, domestic cat hepadnavirus (DCH) by conventional PCR (cPCR) and quantitative PCR (qPCR), and for feline leukaemia virus (FeLV) by qPCR. Point-of-care serology for FeLV p27 antigen and antibodies recognising feline immunodeficiency virus (FIV) p15 and p24 was performed. DCH DNA was detected in the serum of 2/120 cats (1.67%). Sequencing and phylogenetic analysis showed that the DCH detected in Chile occupies a position outside the main clustering of DCH in the near-complete genome tree. Progressive (antigen-positive, provirus-positive) and regressive (antigen-negative, provirus-positive) FeLV infections were identified in 6/120 (5%) and 9/120 (7.5%) of cats. A total of 2/120 (1.7%) cats had dual FeLV/FIV infection, and another 2 cats had FIV infection alone. This study shows that the global footprint of DCH includes South America with a low molecular frequency in Chile, similar to that reported in the USA. Progressive FeLV infection is relatively common in urban Chile, and male cats are at greater risk than females. Testing and control measures for pathogenic retroviruses are indicated. The potential impact of FeLV, FIV and DCH on Chile's wildcat species is worthy of further investigation.

Assessing micro-macroparasite selective pressures and anthropogenic disturbance as drivers of immune gene diversity in a Neotropical wild cat

Anthropogenic environmental change is reducing available habitat for wild species, providing novel selection pressures such as infectious diseases and causing species to interact in new ways. The potential for emerging infectious diseases and zoonoses at the interface between humans, domestic animals, and wild species is a key global concern. In vertebrates, diversity at the major histocompatibility complex MHC is critical to disease resilience, and its study in wild populations provides insights into eco-evolutionary dynamics that human activities alter. In natural populations, variation at MHC loci is partly maintained by balancing selection, driven by pathogenic selective pressures. We hypothesize that MHC genetic diversity differs between guigna populations inhabiting human-dominated landscapes (higher pathogen pressures) versus more natural habitats (lower pathogen pressures). We predict that MHC diversity in guignas would be highest in human-dominated landscapes compared with continuous forest habitats. We also expected to find higher MHC diversity in guignas infected with micro and macro parasites (higher parasite load) versus non infected guignas. We characterized for the first time the genetic diversity at three MHC class I and II exons in 128 wild guignas (Leopardus guigna) across their distribution range in Chile (32-46° S) and Argentina, representing landscapes with varying levels of human disturbance. We integrated MHC sequence diversity with multiple measures of anthropogenic disturbance and both micro and macro parasite infection data. We also assessed signatures of positive selection acting on MHC genes. We found significantly higher MHC class I diversity in guignas inhabiting landscapes where houses were present, and with lower percentage of vegetation cover, and also in animals with more severe cardiorespiratory helminth infection (richness and intensity) and micro-macroparasite co-infection. This comprehensive, landscape-level assessment further enhances our knowledge on the evolutionary dynamics and adaptive potential of vertebrates in the face of emerging infectious disease threats and increasing anthropogenic impacts.

Adenovirus surveillance in wild carnivores from Brazil

Landscape transformation favors the spread of new pathogens that can be shared between domestic and wild animals. Certain adenoviruses (e.g., canine adenovirus 1 and 2, family Adenoviridae) can infect domestic and wild carnivores. In domestic canids, these viruses are associated with hepatic and respiratory diseases (among others). Nevertheless, information regarding adenovirus pathogenicity and molecular features in wild carnivores is still limited. Herein we surveyed adenovirus in free-ranging carnivores from Brazil. Total DNA was extracted from and subsequently tested by a nested panPCR in spleen and/or lung of 52 carnivores, representing species of the following families: Canidae (n = 4), Felidae (n = 3), Mustelidae (n = 2) and Procyonidae (n = 2). The obtained sequences were compared to others available at GenBank. Available tissue samples from the positive cases were evaluated histopathologically. One out of 52 (1.9%, CI 95%, 0.0-5.7%) carnivores was positive; a roadkilled ocelot (Leopardus pardalis). The obtained sequence presented a low deduced amino acid (78.1%) similarity with the closest adenovirus, identified in a pinniped from the United States of America. This fact and its detection in a novel host suggest it may be representative of a novel species and denominated ocelot adenovirus 1. None of the gross and microscopic findings of the positive case were associated with adenovirus. To the authors' knowledge, this is the first report of adenovirus in wild felids of South America and the second worldwide. Further studies are necessary to assess the epidemiology and potential pathogenicity of this agent in wild carnivores.

Management of Suspected Cases of Feline Immunodeficiency Virus Infection in Eurasian Lynx (Lynx lynx) During an International Translocation Program

The Eurasian lynx (Lynx lynx) population in Switzerland serves as a source for reintroductions in neighboring countries. In 2016–2017, three lynx from the same geographical area were found seropositive for feline immunodeficiency virus (FIV) in the framework of an international translocation program. This novel finding raised questions about the virus origin and pathogenicity to lynx, the emerging character of the infection, and the interpretation of serological results in other lynx caught for translocation. Archived serum samples from 84 lynx captured in 2001–2016 were retrospectively tested for FIV antibodies by Western blot. All archived samples were FIV-negative. The three seropositive lynx were monitored in quarantine enclosures prior to euthanasia and necropsy. They showed disease signs, pathological findings, and occurrence of co-infections reminding of those described in FIV-infected domestic cats. All attempts to isolate and characterize the virus failed but serological data and spatiotemporal proximity of the cases suggested emergence of a lentivirus with antigenic and pathogenic similarities to FIV in the Swiss lynx population. A decision scheme was developed to minimize potential health risks posed by FIV infection, both in the recipient and source lynx populations, considering conservation goals, animal welfare, and the limited action range resulting from local human conflicts. Development and implementation of a cautious decision scheme was particularly challenging because FIV pathogenic potential in lynx was unclear, negative FIV serological results obtained within the first weeks after infection are unpredictable, and neither euthanasia nor repatriation of multiple lynx was acceptable options. The proposed scheme distinguished between three scenarios: release at the capture site, translocation, or euthanasia. Until April 2021, none of the 40 lynx newly captured in Switzerland tested FIV-seropositive. Altogether, seropositivity to FIV was documented in none of 124 lynx tested at their first capture, but three of them seroconverted in 2016–2017. Diagnosis of FIV infection in the three seropositive lynx remains uncertain, but clinical observations and pathological findings confirmed that euthanasia was appropriate. Our experiences underline the necessity to include FIV in pathogen screenings of free-ranging European wild felids, the importance of lynx health monitoring, and the usefulness of health protocols in wildlife translocation.

Patterns of Exposure and Infection with Microparasites in Iberian Wild Carnivores: A Review and Meta-Analysis

We use a suite of meta-analytic and comparative methods to derive fundamental insights into how sampling effort, pathogen richness, infection prevalence, and seroprevalence vary across Carnivora taxa and Iberian geography. The red fox was the most studied species, the wolf and Iberian lynx were disproportionally studied, and the Arctoidea were understudied. Sampling effort was higher in Mediterranean areas, but central Spain showed the higher pathogen richness. Excluding studies analyzing fecal samples, 53 different pathogens have been detected in Iberian carnivores, including 16 viruses, 27 bacteria, and 10 protozoa but no fungi. Sampling effort and pathogen diversity were generally more similar among closely related carnivore species. Seropositivity to viruses was lower and higher in the Mustelinae and the Canidae, respectively, and seropositivity to protozoa was higher in both taxa. Canine distemper virus exposure was greatest in canids and mustelids. Carnivore protoparvovirus-1 exposure was greatest in the Atlantic regions, and the Felidae and the Musteloidea had lower infection prevalence. A subclade of the Mustelidae had a greater prevalence of Leishmania infection. We observed no relationships between host phylogenetic distance and pathogen sharing among species. Lastly, we identify important research pitfalls and future directions to improve the study of infectious disease in Iberian wild carnivore communities.

Puma (Puma concolor) in the Neighborhood? Records Near Human Settlements and Insights into Human-Carnivore Coexistence in Central Chile

Simple Summary

The presence of carnivores near human settlements is a poorly studied topic that generates concern and perception of risk in some human communities, especially for medium to large felids. Apart from the conflict of the potential predation of livestock, there is the insecurity perception of a potential attack on people. To gain a better understanding of how, when, and how close pumas approached human settlements, we analyze 51 puma records near populated areas over eight years in central Chile. The results show that pumas approached human-populated areas; in 23.5% of the records pumas are found between 0 and 999 m from the nearest human settlement, 25.5% are between 1000 and 4999 m, and 51% are over 5000 m. We associate puma records with landscape features, such as mountain ranges, land-use, road, and urban infrastructure; and based on previous knowledge of puma biology, behavior, and habitat preference, we identify their area of occupation and the potential biological corridor used for their movements from the Andes Range to the coast. Our results show the adaptability of pumas to human-dominated landscapes, and their capacity to overcome landscape barriers, such as human infrastructure, contributing to a better understanding of the population dynamics in the study area. Studies on human–carnivore coexistence, through formulas that consider local realities and the reduction of implicit risks for humans, are urgently needed, both globally and locally, and likely the only way to secure the long-term conservation of pumas in human-dominated landscapes.

Abstract

The wildland–urban interface lies at the confluence of human-dominated and wild landscapes—creating a number of management and conservation challenges. Wildlife sightings near human settlements have appeared to increase in the last years. This article reports 51 records of presences, sightings, and livestock attacks of Puma concolor, a large-sized felid, collected from 2012 to 2020 across the O’Higgins region in central Chile. Puma records were concentrated in the east of the region in the Andes Range and foothills (90%). The number of puma records is higher in the last four to six years than in previously studied years. Of the 51 records, 23.5% are between 0 and 999 m from the nearest human settlement (classified as very close), 25.5% are between 1000 and 4999 m (moderately close), and 51% are over 5000 m (distant). Most of the sightings are recorded in the summer (35%) and spring (29%). We identify an area of approximately 9000 km² of suitable habitat as the most probable corridor effectively connecting pumas moving between eastern and western areas, encompassing the Angostura de Paine mountain range. Our results contribute to the understanding of the presence and movements of P. concolor near urban areas and human settlements, confirming their persistence in and adaptation to human-dominated landscapes. We also provide insights into human–carnivore coexistence in the current global context in the densely populated central Chile.