Background: In an era of unprecedented socio-ecological changes, managing wildlife health demands high-quality data collection and the engagement of local communities.Blastocerus dichotomus, the largest South American deer, is Vulnerable to extinction mainly due to habitat loss. Diseases have been recognised as a potential threat, and winter mortality has been historically described in marsh deer populations from Argentina. Field difficulties have, however, prevented in-depth studies of their health status.Results: Between May 2014 and April 2017, we investigated marsh deer morbidity and mortality in the two largest populations in Argentina. We collected data by means of a passive surveillance system that involved a network of researchers, field partners (veterinarians, park rangers, and local community), and decision makers. We sampled marsh deer during as well as outside mortality events. A total of 44 marsh deer with different body condition scores were evaluated. We obtained haematology and biochemistry values from animals with good body condition score. Marsh deer with poor body condition had a high burden of the ticksAmblyomma tristeandRhipicephalus microplus. Vector-borne agents such asTheileria cervi,Trypanosoma theileri, Trypanosoma evansi, Ehrlichia chaffeensis, Anaplasma platys, Anaplasma odocoilei, Anaplasma marginale, andCandidatus Anaplasma boleensewere also found.Haemonchusspp.,Ostertagiaspp., andTrichostrongylusspp. were the most frequent gastrointestinal parasites in deer with poor body condition. A Multiple Correspondence Analysis reinforced a possible association of winter period with lower body score condition, high tick loads, infection withE. chaffeensis, and presence of harmful gastrointestinal parasites.Conclusions: Our approach allowed the establishment of a participatory surveillance network of marsh deer morbidity and mortality in Argentina. We report and analyse the first data obtained opportunistically within the framework of this network, providing information on the infectious and parasitic agents in marsh deer populations. The occurrence ofFasciola hepaticaandLeptospira interrogansserovarpyrogenesis reported for the first time in wild marsh deer from Argentina. Our data will be useful to improve the interpretation of future mortality events. The field implementation of a surveillance network is key to a holistic approach to wildlife diseases.

Vaccines to preventTrypanosoma cruziinfection in humans or animals are not available, and in many settings, dogs are an important source of domestic infection for the insect vector. Identification of infected canines is crucial for evaluating peridomestic transmission dynamics and parasite control strategies. As immune control ofT. cruziinfection is dependent on humoral and cell-mediated immune responses, we aimed to define a serodiagnostic assay and T cell phenotypic markers for identifying infected dogs and studying the canineT. cruzi-specific immune response. Plasma samples and peripheral blood mononuclear cells (PBMCs) were obtained from forty-two dogs living in aT. cruzi-endemic region. Twenty dogs were known to be seropositive and nine seronegative by conventional serologic tests two years prior to our study. To determine canine seroreactivity, we tested sera or plasma samples in a multiplex bead array against eleven recombinantT. cruziproteins. Ninety-four percent (17/18) of dogs positive by multiplex serology were initially positive by conventional serology. The frequency of IFNγ-producing cells in PBMCs responding toT. cruzi correlated to serological status, identifying 95% of multiplex seropositive dogs. Intracellular staining identified CD4⁺and CD8⁺T cell populations as the sources ofT. cruzilysate-induced IFNγ. Low expression of CCR7 and CD62L on CD4⁺and CD8⁺T cells suggested a predominance of effector/effector memory T cells in seropositive canines. These results are the first, to our knowledge, to correlateT. cruzi-specific antibody responses with T cell responses in naturally infected dogs and validate these methods for identifying dogs exposed toT. cruzi.

The maned wolf Chrysocyon brachyurus, the fourth largest canid, is categorized as Near Threatened on the IUCN Red List. The objectives of this study were to update information on the occurrence of this species in Argentina, compare the current distribution to that previously described for 1988–2008, and indicate the areas in which the species is exposed to particular hazards. We created a database that included 1,051 new records of C. brachyurus for 2009-2021, in addition to records for 1988–2008 that had not been reported previously. We calculated the area of occupancy of the species in Argentina to be 500,000 km². Most of the new records of C. brachyurus are in the Chaco Seco, Espinal and Pampas ecoregions. Our findings indicate a current area of occupancy 61% higher than that calculated from records for 1988–2008. However the location and frequency of reported threats and the intense environmental transformation that characterizes the areas for which we obtained new records suggest counterintuitive implications for the conservation of the species because of increased human–wildlife interactions. Our study reveals the need for systematic research to improve the understanding of the ecological processes that affect the maned wolf in Argentina, and will aid in the development of conservation strategies for the species.

Anaplasma marginale, a well-known cattle pathogen of tropical and subtropical world regions, has been previously molecularly characterized in a giant anteater (Myrmecophaga tridactyla) from Corrientes, Argentina. Ticks or other hematophagous arthropod involved in the wild transmission cycle remained unknown. The aim of the present study was to analyze the simultaneous occurrence of A. marginale in blood samples and ticks from giant anteaters from Corrientes in order to investigate if ticks could be relevant in the transmission among these mammals. Blood samples from 50 giant anteaters collected in different years and 26 ticks Amblyomma dubitatum and A. sculptum were studied through the molecular amplification of two unequivocal species-specific genes from A. marginale: msp5 and msp1β. Twenty five giant anteaters and tick organs (salivary glands, gut and oviduct) from 11 ticks tested positive to the A. marginale DNA amplification. The further molecular characterization through MSP1a tandem repeats analysis revealed the presence of genotypes circulating among giant anteaters that had been previously identified in cattle blood samples from the same geographical region. These results confirm the presence of A. marginale in giant anteaters in Corrientes and suggests that A. dubitatum and A. sculptum ticks could be involved in the transmission among giant anteaters. Future studies will determine the role of these tick species in the wild transmission cycle in the study area and the eventual connection with the domestic cycle.

Las modificaciones ambientales generan entornos de interfaz en los que la transmisión de Leptospira spp. puede verse afectada. Con el objetivo de identificar y analizar variables ecoambientales asociadas a potenciales reservorios de Leptospira spp. en la Reserva Ecológica Costanera Sur (RECS) (Buenos Aires, Argentina) y áreas urbanizadas contiguas, se realizó un muestreo por conveniencia en líneas transectas, estratificado y proporcionado. Fueron capturados 170 mamíferos de 11 especies y se analizó la presencia de Leptospira spp. por serología, cultivo y PCR. En áreas conservadas, se registraron mayormente Didelphis albiventris y Deltamys kempi, mientras que el Oligoryzomys flavescens también fue hallado en áreas degradadas, y la Rattus norvegicus solo fue encontrada en áreas degradadas. No se detectó Leptospira spp. en los mamíferos silvestres. Un perro sin tenedor responsable resultó positivo por ser0ología. Las condiciones ambientales de la RECS sugieren un ecosistema poco propicio para Rattus, evidenciando la importancia de la conservación de áreas naturales en entornos urbanos.