Sin Nombre Virus Infection of Deer Mice in Montana: Characteristics of Newly Infected Mice, Incidence, and Temporal Pattern of Infection

Abstract

ABSTRACT:Sin Nombre virus (SNV), hosted by the deer mouse (Peromyscus maniculatus), is the principal cause of hantavirus pulmonary syndrome (HPS) in North America. To improve our understanding of factors that contribute to the occurrence of HPS, we conducted an extensive field study of the characteristics of newly infected (as determined by recent acquisition of antibody) deer mice and the temporal pattern of antibody acquisition (seroconversion) from 1994 through 2004 in Montana, USA. We sampled 6,584 individual deer mice, of which 2,747 were captured over multiple trapping periods. Among these 2,747 deer mice, we detected 171 instances of seroconversion. There was no relationship between seroconversion and the acquisition of scars. However, recently infected Montana deer mice were more likely to be older, more likely to be males, and more likely to be in breeding condition. In addition, recently infected male deer mice gained less weight over the 1-mo period following seroconversion than did those that did not acquire antibody, suggesting that SNV infection may have negatively impacted the health of infected rodents. Incidence was highly variable among years, and timing of infections was primarily associated with the breeding season (generally early spring through late fall).

Impact of Puumala Virus Infection on Maturation and Survival in Bank Voles: A Capture-Mark-Recapture Analysis

“…Although estimates of survival were markedly different between infected vs. noninfected reproductively inactive bank voles, estimates of survival for infected vs. noninfected reproductively active bank voles did not differ. The latter results are consistent with the findings of Douglass et al (2001) that Sin Nombre virus infection seemed to decrease monthly survival of juvenile and subadult mice by 50%, whereas no difference in survival was found between infected and noninfected adult deer mice. However, their analysis did not account for potential variation in trappability of rodents.…”

“…However, some recent studies no longer support this view. Besides negative effects at the cellular level (Netski et al, 1999) and on body weight (Douglass et al, 2007), indications of lowered host survival due to hantavirus infection have been reported (Douglass et al, 2001;Calisher et al, 2005;Kallio et al, 2007). Furthermore, because of the chronic infection that hantaviruses induce in their host, they are likely to impose a high resource cost throughout their host's lifetime by triggering specific immune responses (Lehmer et al, 2007).…”

“…Allocation models predict that hosts infected with parasites, where impact of infection increases with time, should preferentially allocate resources to reproduction (Gandon et al, 2001). Reproductive activity has indeed been associated with increased infection probability in many hantavirushost studies (Bernshtein et al, 1999;Escutenaire et al, 2002;Douglass et al, 2007;Previtali et al, 2010).…”

Seasonal Variation in Sin Nombre Virus Infections in Deer Mice: Preliminary Results

“…Thus, it is possible that stressful conditions in winter may drive the differences in the proportion of recent infections in May versus September. Additionally, reproductive activity generally begins to increase at the end of winter, peaks during early summer, and declines towards the fall (Douglass et al, 2001). In our study, 79% of adults appeared reproductive in May, compared to only 6% in September.…”

“…46 (28) 31 (13) 33 (18) 33 (6) 29 (17) 100 (5) 17 (18) 50 (2) 13 (16) 0 (2) 0 ( (52) 24 (164) 51 (37) 13 (93) 100 (11) 18 (239) 21 (38) 11 (197) 22 (18) 0 ( mals #14 g were classified as juveniles, whereas those .14 g were classified as adults (Mills et al, 1997;Borucki et al, 2000;Douglass et al, 2001). We collected blood from the retro-orbital sinus upon initial capture during each trapping season.…”