Orthohantavirus infection in two rodent species that inhabit wetlands in the central-east region of Argentina

Abstract

Hantavirus pulmonary syndrome (HPS) is an emerging infectious disease caused by orthohantaviruses associated to rodents of the Cricetidae family, Sigmodontinae subfamily, in the American continent. Previous research carried out in central-east region of Argentina, recorded potential orthohantavirus host rodents in diverse environments, but infected rodents were particularly present on Paraná wetlands islands. The aims of this research were (1) to determine the orthohantavirus host in the rodent community focused on islands of Paraná River Delta, an endemic zone of HPS, (2) to identify temporal and spatial factors associated with orthohantavirus prevalence variations, (3) to compare the individual characteristics of seropositive and seronegative rodents and, (4) to explore the association between orthohantavirus seroprevalence and rodent community characteristics in the Paraná River Delta, central-east region of Argentina. Capture of small rodents was done between August 2014 and May 2018 on seven islands located in central-east region of Argentina. In this HPS endemic zone, 14.9% of Oligoryzomys flavescens and 1.5% of Oxymycterus rufus of the sampled rodents had antibodies against orthohantavirus. The individuals that were more likely to become seropositive were the reproductively active adult males. Even though O. flavescens inhabit all islands, the seropositive individuals were only present in two of these, suggesting spatial heterogeneity in the viral distribution. We found that two months later of periods with low temperature, seroprevalence increased probably due to a higher proportion of adults in the population. Additionally, higher seroprevalence was associated with greater diversity of the rodent assemblage. This association could support the idea that a rescue effect or amplification of the prevalence of orthohantavirus would be taking place by means of secondary host as O. rufus, a novelty for this species and for the region. This finding may be significant if one takes into account that O. rufus was the second most abundant species in the area of islands studied and is one of the most abundant species on the islands and riparian sectors of the study zone. In conclusion, the relative risk of HPS could be high on wetlands of Paraná River Delta in the central-east region of Argentina where several favourable factors for the transmission of orthohantavirus are combined, such as the presence of several host species, two of them numerically dominant, high percentages of infection and a high degree of occupational exposure of the human population due to rural activities, the most frequently associated nationwide with HPS.

Filling the gaps in the Argentinian distribution of orthohantavirus: First finding of Lechiguanas virus in rodents from Corrientes, Argentina

“…This study was conducted during autumn, when the proportion of young rodents (not yet infected) was high, but hantavirus prevalence is likely to be higher during other periods of the year, due to a delayed density dependence on the incidence of infection (Engelthaler et al, 1999; Kuenzi et al, 2007; Suzán et al, 2009) or to a major proportion of adults by the end of winter (e.g. individuals most likely to be infected; Maroli, Bellomo, et al, 2022; Maroli, Burgos, et al, 2022). Despite the low viral prevalence, the dominance of the reservoir species in the rodent community, and the use of an area constantly frequented by humans (such as the camping area), high risk of transmission to humans is shown.…”