Seroprevalence of leptospiral antibodies in rodents from riverside communities of Santa Fe, Argentina

Abstract

Background Leptospirosis is a zoonotic disease that can be transmitted by contact with the urine of infected mammals. Rodents play a mayor role in the transmission of leptospires to humans. The province of Santa Fe reports the greatest number of cases in Argentina. Yet, in this region, there are still knowledge gaps regarding the diversity of rodent species that may be hosts of pathogenic leptospires. The aims of this study were to evaluate the presence of leptospiral antibodies in rodents from three riverside communities of Santa Fe, and to identify factors associated with leptospiral infection. Methodology/Principal findings Each community was divided into three environmental settings based on the level of human disturbance, and sampled during two springs (Sep-Oct 2014 and 2015) and one autumn (Mar-Apr 2015). Serum samples of captured sigmodontine and murine rodents were tested for leptospiral antibodies by enzyme-linked immunosorbent assay (ELISA), and microagglutination test (MAT) was used to assess the infecting serovar in seropositive individuals. Factors influencing seropositivity were analyzed using logistic regression models. We caught 119 rodents, of which 101 serums were suitable for analysis. Most frequently trapped species were Scapteromys aquaticus, Akodon azarae and Oligoryzomys spp., with seroprevalences of 41.3%, 42.9% and 55% respectively. Seropositivity was higher in individuals with an average body condition score and in those that were sexually mature, but in the latter the differences were marginally significant.

Emerging Hantaviruses in Central Argentina: first case of Hantavirus Pulmonary Syndrome caused by Alto Paraguay Virus and a novel orthohantavirus in Scapteromys aquaticus rodent

“…S. aquaticus can be found in semi-aquatic habitats, such as swamps, water courses, or flooded areas with low vegetation of the argentine ecoregions of Humid Chaco, Paraná flooded savanna, Espinal, Pampas and Iberá, as well as in western Uruguay, southern Paraguay and southern Brazil [29-31] (Fig 2). This species was also found to be a reservoir of pathogenic leptospires in areas of the Paraná flooded savanna from the provinces of Santa Fe and Buenos Aires [32, 14, 15]. The knowledge gaps on lack of evidence about the role of some rodent species as reservoirs hosts of these hantaviruses, favors the risk of orthohantavirus transmission and hinders HPS prevention.…”

“…Detailed information on the study protocol can be found in Ricardo et al . [14, 15]. Briefly, each community was splitted into 3 study sites based on their level of human disturbance, and 25 trapping stations (consisting of a Sherman trap and a live-cage trap) were set per site during 3 consecutive nights.…”

“…Morphometric and reproductive features, body condition score [16] and presumptive species were recorded for each captured animal. Rodent species were subsequently confirmed by inspection of skull morphology or by molecular identification through mitochondrial genes from liver and/or lung samples [15]. Samples were stored in liquid nitrogen during the trapping session and for their transportation to the laboratory.…”

Emerging hantaviruses in Central Argentina: First case of Hantavirus Pulmonary Syndrome caused by Alto Paraguay virus, and a novel orthohantavirus in Scapteromys aquaticus rodent

“…We placed 25 trapping stations (consisting of a Sherman trap and a live-cage trap) per site during 3 consecutive nights. Traps were placed on vacant lots, road edges, river banks, and houses peridomicile at regular intervals of approximately 10 m. Detailed information on the study protocol can be found in Ricardo et al [ 14 , 15 ]. Blood samples were collected by cardiac puncture and tissue samples by systemic necropsy.…”

Modeling of leptospirosis outbreaks in relation to hydroclimatic variables in the northeast of Argentina

“…Regarding the actual value to be used in the model, a rodent population study could be performed to quantify what percentage is actually infected, as the one carried out by Ricardo et al (2020). On the other hand, controlling such population and minimizing the contact with the human population would be effective measures to reduce the impact of a leptospirosis outbreak, just to mention an example.…”