RESUMO

Monitoring the invasive exotic species and their effect on native fauna is fundamental for their effective control. The objective of this research is to evaluate the spatiotemporal distribution and overlap of medium-large-sized fauna in El Palmar National Park, Argentina, to consider potential negative interactions between native and exotic species. Camera traps were distributed in 27 sites between 2017 and 2019. Spatial and temporal overlap was estimated for every pair of exotic-native taxa. With 2673 camera days, two exotic and seven native taxa were recorded. All species were distributed along the extension of the National Park but in different numbers of sites. Exotic axis deer (Axis axis) was recorded in all sites but one, and exotic wild boar (Sus scrofa) occurred at only one-third of the sites surveyed. The occurrence of native mammals ranged between 26% (Geoffroy's cat, Leopardus geoffroyi) and 67% (capybara, Hydrochoerus hydrochaeris). Spatial overlap between native and exotic species was high overall and was higher in winter when species moved over larger areas to look for limited resources. Except for greater rhea (Rhea americana), which was diurnal, all species had crepuscular or nocturnal patterns. Both exotic species had an intermediate/high overlap in their activity pattern with almost all native species, including some species with similar diets, but the hours of their maximum activities did not strictly coincide. However, the existence of differences in the exotic species' activity patterns compared to their patterns in other areas where they inhabit could indicate segregation in daily activity to relax competition.

RESUMO

Few cases of hantavirus pulmonary syndrome have been reported in northeastern Argentina. However, neighboring areas show a higher incidence, suggesting underreporting. We evaluated the presence of antibodies against orthohantavirus in small rodents throughout Misiones province. Infected Akodon affinis montensis and Oligoryzomys nigripes native rodents were found in protected areas of Misiones.

Assuntos

RESUMO

Hantavirus Pulmonary Syndrome (HPS) is an emerging infectious disease caused by orthohantaviruses in the Americas. In Argentina, since 1995, several reservoirs and virus variants have been described, but the northeastern and central endemic zones in the country include an area without human or rodent infections, despite sharing rodent species with areas with that disease. The aim of this study was to search for orthohantavirus in rodent communities that inhabit this area, which borders two endemic areas of HPS. Small rodents were captured in June of 2022 through a total effort of 644 trap nights distributed in five grids located in the Iberá National Park, Corrientes, Northeastern Argentina. All rodents were sexed, weighed, and the species was recorded. Blood samples were extracted to detect ANDV-specific immunoglobulin G (IgG), and to extract the RNA virus. Trimmed sequences were mapped against reference sequences from GenBank. We captured a total of 36 Oligoryzomys flavescens and 15 Oxymycterus rufus. We detected the O. flavescens species infected with Lechiguanas orthohantavirus in the camping area of the National Park. A nucleotide comparison with previously published sequences shows a 98.34% similarity to the virus obtained from a human case of HPS reported in the adjacent Misiones province. This study demonstrated, for the first time, that O. flavescens is a host of the Lechiguanas orthohantavirus in this zone and contributes to closing information gaps on the distribution of orthohantavirus in Argentina. Additionally, the high similarity with the hantavirus found in the human case of Misiones suggests that the reservoir in that province would also be O. flavescens (not previously confirmed). This information permits us to focus on the preventive measurements to protect the human population.

Assuntos

RESUMO

Previous research conducted in central-east region of Argentina recorded potential orthohantavirus host rodents in diverse environments, but no research has focused particularly on islands, the environments that present the greatest risk to humans. For this reason, the aims of this research were to determine the orthohantavirus host in the rodent community focused on islands of Paraná River Delta, central-east region of Argentina, to identify temporal and spatial factors associated with orthohantavirus prevalence variations, to compare the functional traits of seropositive and seronegative rodents, and to explore the association between orthohantavirus prevalence and rodent community characteristics between August 2014 and May 2018. With a trapping effort of 14,600 trap-nights, a total of 348 sigmodontine rodent specimens belonging to seven species were captured 361 times. The overall antibody prevalence was 4.9%. Particularly, 14.9% of Oligoryzomys flavescens and 1.5% of Oxymycterus rufus, mainly reproductively active adult males, had antibodies against orthohantavirus. Even though O. flavescens inhabit all islands, our results suggest spatial heterogeneity in the viral distribution, with two months after periods of low temperature presenting increases in seroprevalence. This could be a response to the increased proportion of adults present in the rodent population. In addition, an association was found between the high seroprevalence and the diversity of the rodent assemblage. We also found 1.5% of O. rufus exposed to orthohantavirus, which shows us that further investigation of the ecology of the virus is needed to answer whether this species act as a spillover or a new competent host.

Assuntos

RESUMO

Hantavirus pulmonary syndrome (HPS) is a zoonotic emerging infectious disease caused by New World orthohantaviruses (family Hantaviridae) hosted by rodents of the family Cricetidae. In Argentina, one of its main hosts is the sigmodontine rodent Oligoryzomys flavescens, a widely distributed mouse of the Pampas, Delta and Espinal ecoregions of central-east Argentina. Because the abundance of the reservoir and its proportion in the rodent community affects both virus prevalence and human exposure risk, its estimation throughout its known geographical distribution is of key importance for the design of public health strategies to prevent HPS. The aim of this study was therefore to model the relative abundance of O. flavescens in most of the Pampas ecoregion within Buenos Aires Province, Argentina, where hantavirus pulmonary syndrome is endemic. To do this we used owl-pellet samples collected between 2006 and 2008 from 51 sites distributed throughout most of Buenos Aires province. Mammalian prey in each pellet was identified to the lowest possible taxonomic level by examination of the skulls, dentaries and molars. We modelled the frequency of O. flavescens found in each sample as a function of climatic, environmental, and topographic data of each site. The two best models were applied to a Geo referential Information System to build maps of estimated frequency (as a proxy of relative abundance) within Buenos Aires province. Estimated relative abundance of O. flavescens in Buenos Aires province was significantly associated with annual mean temperature, annual precipitation and presence of freshwater bodies, and varied among sub-regions, with the Inland and Rolling Pampas being the regions with highest frequencies. Knowing in which areas O. flavescens abundance is expected to be higher can be used to concentrate limited sanitary efforts in those areas that are most needed in order to reduce transmission and increase detection.

Assuntos

RESUMO

Hantavirus Pulmonary Syndrome (HPS) is an emerging infectious disease of the Americas. Eight native rodent species have been identified as HPS virus reservoirs in Argentina. The aim of this work was to detect the orthohantavirus genotypes present in a rodent community that inhabits a zone where a fatal HPS case occurred within an endemic locality of Central Argentina. We captured 27 rodents with a trapping effort of 723 trap nights. We detected 14.3% of infected Akodon azarae with the Pergamino genotype. This result expands the known distribution of this orthohantavirus. Although the Pergamino genotype has not been associated with human cases, the information about its distribution is relevant for risk assessment against potential changes in the virus infectivity.

Assuntos

RESUMO

Hantavirus pulmonary syndrome is an emerging infectious disease caused by viruses of the genus Orthohantavirus. The rodent Oligoryzomys flavescens is distributed along four countries of South America. In Argentina, O. flavescens acts as a reservoir of three genotypes of ANDV orthohantavirus. The aims of this work were to estimate home range size and movements-with spool-and-line and radiotelemetry-of infected and non-infected O. flavescens in order to understand the spread and transmission of the virus. O. flavescens use a wide area to satisfice its requirements, reaching a home range of 1.82 ha during spring. Orthohantavirus infection did not change the behaviour of individuals. We observed a great overlapping in the home range of infected and non-infected individuals resulting in a high probability of virus dispersion on rodent population. These results show that human health risks could be high on island environments and knowledge about the movement ecology of O. flavescens provides useful information on prevention.

Assuntos

RESUMO

Species diversity has been proposed to decrease prevalence of disease in a wide variety of host-pathogen systems, in a phenomenon labeled the dilution effect. This phenomenon was first proposed and tested for vector-borne diseases but was later extended to directly transmitted parasite systems such as hantavirus. Though there seems to be clear evidence for the dilution effect in some hantavirus/rodent systems, the generality of this hypothesis remains debated. In the present meta-analysis, we examined the evidence supporting the dilution effect for hantavirus/rodent systems in the Americas. General linear models employed on data from 56 field studies identified the abundance of the reservoir rodent species and its relative proportion in the community as the only relevant variables explaining the prevalence of antibodies against hantavirus in the reservoir. Thus, we found no clear support for the dilution effect hypothesis for hantavirus/rodent systems in the Americas.

Assuntos

RESUMO

Hantavirus pulmonary syndrome (HPS) is a severe emerging endemic disease of the Americas. Because hantavirus reservoirs are sylvatic rodents, HPS risk has been associated with occupational and recreational activities in natural and rural environments. The aim of this study was to analyze the risk of HPS in an endemic province of Argentina. For this, we explored the relationship between HPS cases occurring in Entre Ríos province between 2004 and 2015 and climate, vegetation, landscape, reservoir population, and rodent community characteristics by means of generalized linear models. We modeled HPS occurrence at each site, and both the incidence and number of cases grouped by department. The resulting best model of each analysis was applied in a GIS to build HPS risk maps. Risk of occurrence of HPS increased with tree cover and decreased with distance to rivers. We identified the south of Entre Ríos as the area with higher HPS risk, and therefore, where HPS prevention measures should be more urgently applied. Risk maps based on data available in the public domain are a useful tool that should be used by decision makers to concentrate surveillance and control efforts in those areas with highest HPS risk.

Assuntos

RESUMO

Hantavirus pulmonary syndrome is a severe cardio pulmonary disease transmitted to humans by sylvan rodents found in natural and rural environments. Disease transmission is closely linked to the ecology of animal reservoirs and abiotic factors such as habitat characteristics, season or climatic conditions. The main goals of this research were: to determine the biotic and abiotic factors affecting richness and abundance of rodent species at different spatial scales, to evaluate different methodologies for studying population of small rodents, and to describe and analyze an ecologically-based rodent management experience in a highly touristic area. A 4-year study of small rodent ecology was conducted between April 2007 and August 2011 in the most relevant habitats of El Palmar National Park, Argentina. Management involved a wide range of control and prevention measures, including poisoning, culling and habitat modification. A total of 172 individuals of 5 species were captured with a trapping effort of 13 860 traps-nights (1.24 individuals/100 traps-nights). Five rodent species were captured, including 2 hantavirus-host species, Oligoryzomys nigripes and Akodon azarae. Oligoryzomys nigripes, host of a hantavirus that is pathogenic in humans, was the most abundant species and the only one found in all the studied habitats. Our results are inconsistent with the dilution effect hypothesis. The present study demonstrates that sylvan rodent species, including the hantavirus-host species, have distinct local habitat selection and temporal variation patterns in abundance, which may influence the risk of human exposure to hantavirus and may have practical implications for disease transmission as well as for reservoir management.

Assuntos