Cocirculación de virus Junin y otros mammarenavirus en área geográfica sin casos confirmados de Fiebre Hemorrágica Argentina / Co-circulation of Junin virus and other mammarenaviruses in a geographical area without confirmed cases of Argentine Hemorrhagic Fever

Resumen Desde la identificación del virus Junin en la década del 50, se realizaron numerosos estudios en roedores silvestres dentro del área endémica de la Fiebre Hemorrágica Argentina (FHA) que per mitieron registrar, además, actividad del virus de la coriomeningitis linfocitaria (LCMV) y del virus Latino (LATV). La ausencia de casos confirmados de FHA desde la década del 90 en el departamento Río Cuarto, provincia de Córdoba, promovió la vigilancia ecoepidemiológica y de infección del Calomys musculinus (reservorio del virus Junin) y la búsqueda de reservorios e infección de los otros mammarenavirus. Durante dos años de muestreo estacional, con un sistema de captura, marcación y liberación capturamos 857 roedores, que correspondieron 57.3% a los reservorios: C. musculinus (especie más abundante), C. venustus y Mus musculus. Detectamos anticuerpos y caracterizamos molecularmente los tres agentes virales. Observamos una prevalencia de infección de 3.5% (9/254) para virus Junin, 100% (3/3) para LCMV y 24.1% (21/87) para LATV. En conclusión, demostra mos circulación de virus Junin en su roedor reservorio, en una región considerada histórica para FHA con riesgo potencial para la población y cocirculación espacio-temporal de los tres mammarenavirus en la región central de Argentina.

Abstract Since the identification of Junin virus in the 1950s, many studies were carried out in wild rodents within the endemic area of the Argentine Hemorrhagic Fe ver (AHF) that recorded also the activity of the lymphocytic choriomeningitis virus (LCMV) and the Latino virus (LATV). The absence of confirmed cases of AHF since the 1990s in the department of Rio Cuarto, Córdoba province, promoted ecoepidemiological surveillance of infection of Calomys musculinus (Junin virus reservoir) and the search of reservoirs of the other mammarenaviruses. During two years of seasonal sampling, with a capture, mark and release system, 857 rodents were captured, corresponding 57.3% to the rodent reservoirs: C. musculinus, C. venustus and Mus musculus, being the first the most abundant species. Antibodies were detected and the three viral agents were molecularly characterized, showing a prevalence of infection of 3.5% (9/254) for Junin virus, 100% (3/3) for LCMV and 24.1% (21/87) for LATV. In conclusion, we demonstrated Junin virus circulation in its rodent reservoir in a region considered historic for AHF with potential risk for the population and the spatio-temporal co-circulation of the three mammarenaviruses in the central region of Argentina.

[Co-circulation of Junín virus and other mammarenaviruses in a geographical area without confirmed cases of Argentine Hemorrhagic Fever]. / Cocirculación de virus Junin y otros mammarenavirus en área geográfica sin casos confirmados de Fiebre Hemorrágica Argentina.

Since the identification of Junin virus in the 1950s, many studies were carried out in wild rodents within the endemic area of the Argentine Hemorrhagic Fever (AHF) that recorded also the activity of the lymphocytic choriomeningitis virus (LCMV) and the Latino virus (LATV). The absence of confirmed cases of AHF since the 1990s in the department of Rio Cuarto, Córdoba province, promoted ecoepidemiological surveillance of infection of Calomys musculinus (Junin virus reservoir) and the search of reservoirs of the other mammarenaviruses. During two years of seasonal sampling, with a capture, mark and release system, 857 rodents were captured, corresponding 57.3% to the rodent reservoirs: C. musculinus, C. venustus and Mus musculus, being the first the most abundant species. Antibodies were detected and the three viral agents were molecularly characterized, showing a prevalence of infection of 3.5% (9/254) for Junin virus, 100% (3/3) for LCMV and 24.1% (21/87) for LATV. In conclusion, we demonstrated Junin virus circulation in its rodent reservoir in a region considered historic for AHF with potential risk for the population and the spatio-temporal co-circulation of the three mammarenaviruses in the central region of Argentina.

Desde la identificación del virus Junin en la década del 50, se realizaron numerosos estudios en roedores silvestres dentro del área endémica de la Fiebre Hemorrágica Argentina (FHA) que permitieron registrar, además, actividad del virus de la coriomeningitis linfocitaria (LCMV) y del virus Latino (LATV). La ausencia de casos confirmados de FHA desde la década del 90 en el departamento Río Cuarto, provincia de Córdoba, promovió la vigilancia ecoepidemiológica y de infección del Calomys musculinus (reservorio del virus Junin) y la búsqueda de reservorios e infección de los otros mammarenavirus. Durante dos años de muestreo estacional, con un sistema de captura, marcación y liberación capturamos 857 roedores, que correspondieron 57.3% a los reservorios: C. musculinus (especie más abundante), C. venustus y Mus musculus. Detectamos anticuerpos y caracterizamos molecularmente los tres agentes virales. Observamos una prevalencia de infección de 3.5% (9/254) para virus Junin, 100% (3/3) para LCMV y 24.1% (21/87) para LATV. En conclusión, demostramos circulación de virus Junin en su roedor reservorio, en una región considerada histórica para FHA con riesgo potencial para la población y cocirculación espacio-temporal de los tres mammarenavirus en la región central de Argentina.

[Spatial difference in the incidence of Argentine Hemorrhagic Fever and composition and abundance of rodents in the assemblage]. / Diferencia espacial de la incidencia de fiebre hemorrágica argentina y la composición y abundancia de roedores en el ensamble.

BACKGROUND: The Argentine Hemorrhagic Fever (AHF) is a zoonotic disease endemic in a wide area of the humid pampa of Argentina. The etiologic agent is the Junin virus that is maintained in the wild by the rodent Calomys musculinus and transmitted to humans, mainly, through aerosols generated from secretions and excretions. AIMS: To characterize and compare the assemblages of small rodent composition and diversity inside the epidemic, historic and non-endemic zone of AHF and to register C. musculinus abundance in each zone and in each area within each zone, registering the prevalence of infection in rodent populations. METHOD: One central and two peripheral areas were delimited to sample rodents in each zone with different incidence of AHF. Thus, 18 localities were selected to do the sampling in two years. Host abundance between zones and among areas inside each zone and among nearby areas between zones were compared applying nested ANOVA's. RESULTS: In each zone, the rodent assemblage showed differences in composition, diversity and numeric representation of C. musculinus. The epidemic zone was the richest of the three, registering also great host abundance; meanwhile in the historic zone, A. azarae was the dominant numeric species with less number of other species. Regarding the non-endemic zone, the assemblage composition and C. musculinus abundance varied respect the sampled year. Junin virus infection was only detected in C. musculinus individuals corresponding to the epidemic zone, with a prevalence of 2.7 and 1.1% for the years 2007 and 2008, respectively. CONCLUSION: In this system, the abundance of C. musculinus could be impacting over the pathogen dynamic, rather than the assemblage diversity or the A. azarae presence.

Diferencia espacial de la incidencia de fiebre hemorrágica argentina y la composición y abundancia de roedores en el ensamble / Spatial difference in the incidence of Argentine Hemorrhagic Fever and composition and abundance of rodents in the assemblage

Resumen La fiebre hemorrágica argentina (FHA) es una enfermedad zoonótica endémica en una amplia zona de la pampa húmeda de Argentina. El agente etiológico es el virus Junin que es mantenido en la naturaleza por el roedor Calomys musculinus y transmitido, principalmente, al humano a través de aerosoles generados de las secreciones y excreciones. Objetivos: Caracterizar la composición y diversidad de los ensambles de pequeños roedores, determinar la abundancia del hospedador C. musculinus y la prevalencia del virus de la FHA en las zonas epidémica, histórica y no endémica de dicha enfermedad en Argentina. Métodos: Para el muestreo de roedores en cada una de las zonas se demarcaron un área central y dos periféricas para 18 localidades de la región central de Argentina (incluyendo las provincias de Córdoba, Buenos Aires y Santa Fe) muestreadas en dos años. Se comparó la abundancia de C. musculinus entre zonas y entre las áreas dentro de cada zona y áreas cercanas entre zonas, utilizando modelos de análisis de varianza anidados. Resultados. Dentro de cada zona, el ensamble de roedores mostró diferencia espacial en la composición específica, diversidad y abundancia de C. musculinus. La zona epidémica registró mayor número de especies y mayor abundancia del hospedador. En zona histórica se capturó el menor número de especies (de roedores) y Akodon azarae fue la más abundante. En zona no endémica la composición del ensamble y la abundancia de C. musculinus variaron entre los dos años. Sólo se detectó infección por virus Junin en C. musculinus correspondientes a la zona epidémica con una prevalencia de 2,7 y 1,1% para los años 2007 y 2008, respectivamente. Conclusión: En este sistema, la abundancia del hospedador estaría afectando la dinámica espacial de este virus, más que la diversidad del ensamble o la presencia de A. azarae.

Background. The Argentine Hemorrhagic Fever (AHF) is a zoonotic disease endemic in a wide area of the humid pampa of Argentina. The etiologic agent is the Junin virus that is maintained in the wild by the rodent Calomys musculinus and transmitted to humans, mainly, through aerosols generated from secretions and excretions. Aims: To characterize and compare the assemblages of small rodent composition and diversity inside the epidemic, historic and non-endemic zone of AHF and to register C. musculinus abundance in each zone and in each area within each zone, registering the prevalence of infection in rodent populations. Method: One central and two peripheral areas were delimited to sample rodents in each zone with different incidence of AHF. Thus, 18 localities were selected to do the sampling in two years. Host abundance between zones and among areas inside each zone and among nearby areas between zones were compared applying nested ANOVA's. Results: In each zone, the rodent assemblage showed differences in composition, diversity and numeric representation of C. musculinus. The epidemic zone was the richest of the three, registering also great host abundance; meanwhile in the historic zone, A. azarae was the dominant numeric species with less number of other species. Regarding the non-endemic zone, the assemblage composition and C. musculinus abundance varied respect the sampled year. Junin virus infection was only detected in C. musculinus individuals corresponding to the epidemic zone, with a prevalence of 2.7 and 1.1% for the years 2007 and 2008, respectively. Conclusion: In this system, the abundance of C. musculinus could be impacting over the pathogen dynamic, rather than the assemblage diversity or the A. azarae presence.

Temporal and spatial host abundance and prevalence of Andes hantavirus in southern Argentina.

Andes virus (AND) is a hantavirus hosted by the sigmodontine rodent Oligoryzomys longicaudatus in southern Argentina, where it is responsible for most cases of hantavirus pulmonary syndrome (HPS). Our study provides data about the spatial variation in abundance of the rodent host of AND hantavirus. We report results of a longitudinal study performed in a locality of the Andean region of Chubut Province. From November 2003 (spring) to July 2006 (winter), O. longicaudatus was the most common species captured (63%) and it showed significant differences in abundance among habitats and seasons. Most antibody-positive rodents were O. longicaudatus (9.2%), followed by A. longipilis (3.6%) and A. olivaceus (1.5%). The highest number of antibody-positive animals was observed for males that belonged to the heaviest mass classes. Antibody-positive O. longicaudatus were more abundant in brush habitats. We found low richness of rodents and abundance of O. longicaudatus in areas affected by anthropogenic activity. The infection seems to be regionally persistent, but the risk to humans in a landscape would be localized. To develop accurate models for predicting HPS outbreaks, further research is needed to characterize rodent movement patterns across the landscape.