Patterns of infection with Laguna Negra virus in wild populations of Calomys laucha in the central Paraguayan chaco.

Abstract

Abstract. In 1995, an outbreak of hantavirus pulmonary syndrome occurred in the central Paraguayan chaco. The primary reservoir of the virus, Laguna Negra virus, was identified as the vesper mouse, Calomys laucha. Over a 15-month period, we collected 1,090 small mammals at 12 locations representing 4 habitats common in the central Paraguayan chaco. Calomys laucha was common in agricultural habitats and uncommon in the native forest habitat. Populations of C. laucha were greater during the dry season months and declined during the wet season. A total of 643 small mammals were tested for antibodies cross-reactive to Sin Nombre virus. All of the antibody-positive animals were C. laucha (crude antibody prevalence ratio 12.1% [25 of 206]). Antibody prevalence ratio increased with body size and was more common among male (18%; n ϭ 115) than among female (4%; n ϭ 96) vesper mice. Antibody prevalence ratio was highest among animals from cropland habitats (18%; n ϭ 72), followed by thorn scrub (13%; n ϭ 46) and pastureland (7%; n ϭ 81) and may be positively correlated to the proportion of C. laucha in the small mammal community. These data suggest that community-level dynamics, in addition to population-level dynamics, may be involved in the transmission of the virus through natural populations of vesper mice.

Prevalence of infection with hantavirus in rodent populations of central Argentina

“…The higher rates of hantavirus seroprevalence found in larger and reproductively active (i.e., older) individuals of A. azarae, and specially in males, is in agreement with that observed in O. longicaudatus in Southern Argentina by Cantoni et al (2001), in C. laucha in Paraguay by Yahnke et al (2001) in species of Peromyscus in the United States (Abbott et al 1999, Kuenzi et al 1999, and in C. musculinus infected with Junín virus (Mills et al 1994). Differences in seroprevalence among age classes and sexes have been related to horizontal transmission that involves a higher chance of older individuals of being infected, since they have a longer period of exposition to the virus (i.e., the "age factor").…”

“…Strong variations in seroprevalences are not only evident when comparing studies conducted by different authors, but also within habitats and times (Abbott et al 1999. In Argentina and other areas of the Americas seroprevalence range between 3-14% (Calderón et al 1999, Cantoni et al 2001, Yahnke et al 2001. However, the difference in seroprevalence could also be attributed to the different type of antigen used to estimate seroprevalence in each study (Sin Nombre and AND antigens for Calderón et al's and our study, respectively), although Toro et al (1998) did not find differences in serologic results obtained with these two types of antigen.…”

“…Calomys laucha was identified as the reservoir of the virus Laguna Negra, the etiologic agent of HPS in Paraguay (Yahnke et al 2001), while three species of Oligoryzomys have been related to hantavirus transmission: O. longicaudatus (in Chile and Southern Argentina), O. chacoensis (in Northern Argentina, Padula et al 2002), and O. flavescens in Central Argentina and Uruguay (Levis et al 1998, González della Valle et al 2002.…”

Association between Hemorrhagic Fever with Renal Syndrome Epidemic and Climate Factors in Heilongjiang Province, China

“…34 In addition, other studies have shown that rodent populations had a higher proportion of adults in spring-summer months than during the months of autumn and winter. 35,36 As for the present study, monitoring the fluctuations of monthly maximum temperature in the area could be used as an indicator to temporally target the surveillance for HFRS infections.…”

An annotated checklist of the mammals of Paraguay

“…They are valuable in ecological studies, including those concerning anthropogenic disturbance such as landscape and climate change (de la Sancha 2014; de la . Rodents are also important hosts for human pathogens, including hantaviruses, which are known from Paraguay (Yahnke et al 2001;Chu et al 2003Chu et al , 2006Goodin et al 2006;Padula et al 2007;Chu et al 2009;). Studies dealing with population dynamics of rodents in Paraguay have been severely handicapped by lack of field identification tools; reliable keys and much more basic work are still needed in Paraguay.…”