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.

No abstract

No abstract

No abstract

No abstract

In this study, we examined the role of interspeciWc competition between native species and Mus musculus by a removal experiment conducted in vacant areas of the city of Río Cuarto. Abundance, demographic parameters, and habitat occupancy of M. musculus were recorded in grids where native species were removed (experimental grids) and in grids without removal (control grids) from November 2004 to April 2005. During the study period, we observed an increasing trend in the abundance and habitat occupancy by M. musculus in experimental grids, suggesting that interspeciWc competition could be determining the numbers and habitat use of M. musculus in vacant areas of the city of Río Cuarto. Understanding the population ecology of M. musculus in an urban area is crucial to the development of ecologically based pest management to provide eVective management of a pest species.

Since the beginning of the 20th century, man has domesticated his environment and caused the modification of hydraulic conditions during floods. In parallel, civil engineering has strongly progressed in the domain of hydraulic structures but especially the construction of dams and dikes has also massively increased and part of the population has lost the culture of risk by thinking they were completely out of danger from flooding. Events of hydrometeorological origin over the last 25 years has reminded man that the hydraulic infrastructures in place for a few centuries now, are not unalterable. An unmanaged vegetal colonization along the edge of watercourses (protection dikes, retention dams, appointed river banks, ect« FDQ SUHVHQW three types of inconvenience as (i) overflow in the case of watercourse containment, (ii) formation of woody jams which generate a risk of bridge obstructions or water retention, (iii) the presence of trees and their roots which damages the containment systems protecting the territories. It is important to manage the development of this vegetation in order to conserve the positive effects on the area while also limiting the negative impacts. The current boom in vegetation engineering techniques shows that man is relearning how tR OLYH DV D µWHDP´ ZLWK QDWXUH

Argentine hemorrhagic fever (AHF) is a serious endemic disease in Argentina, produced by Junín virus, whose host is the Sigmodontinae rodent . Within the endemic area, human incidence and proportion of infected rodents remains high for 5-10 years after the first appearance of the disease (epidemic [E] zone) and then gradually declines to sporadic cases (historic [H] zone). We tested the hypothesis that host populations within the E zone are large and well connected by gene flow, facilitating the transmission and maintenance of the virus, whereas those in the H and nonendemic (NE) zones are small and isolated, with the opposite effect. We estimated parameters affected by levels of gene flow and population size in 14 populations of: population effective size (), genetic variability, and mean relatedness. Our hypothesis was not supported: the lowest levels of variability and of and the highest genetic relatedness among individuals were found in the H zone. Populations from the NE zone displayed opposite results, whereas those in the E zone showed intermediate values. If we consider that populations are first NE, then E, and finally H, a correlative decrease in was observed. Chronically infected females have a low reproductive success. We propose that this would lower because each cohort would originate from a fraction of females of the previous generation, and affect other factors such as proportion of individuals that develop acute infection, probability of viral transmission, and evolution of virulence, which would explain, at least partly, the changing incidence of AHF.