De Jaegere F, Chalon P, Sulon J, Beckers J-F, Rozenfeld F, Pastoret P-P, Escutenaire S. 2003. Relationship between steroid hormones concentrations and Puumala virus infection in adult male bank voles (Clethrionomys glareolus). 52nd Annual meeting of the American Society of Tropical Medicine and Hygiene. Dec. 3-7. Philadelphia (USA). [Poster 538]
Population densities, breeding and aggressive behaviors are involved in the epidemiology of hantavirus infection in rodents. The hormonal status, influenced by the social environment, could also play a role in rodent susceptibility to hantavirus infection. The stress hormone corticosterone and testosterone are reported to depress immunity and to increase risks of infections. In a Belgian capture-mark-recapture survey, population densities and the prevalence of Puumala virus (PUUV) infection in bank voles (Clethrionomys glareolus) were the highest in 1996 and 1999 epidemic years for hemorrhagic fever with renal syndrome. During this study, serum testosterone and fecal corticosterone concentrations in adult males were measured by radioimmunoassay. Tested sera were collected from spring 1997 to fall 1999.Feces were available in fall 1998 and spring 1999. In 1997 and 1999, testosterone concentrations were lower in fall, i. e. at the end of the breeding season, than in the previous spring. No decrease in testosterone concentrations was recorded in fall 1998 before the peak in population density.Concentrations of corticosterone were higher in spring 1999 than in the previous fall, as was the prevalence of infection. Breeding activity and the presence of wounds were associated with higher testosterone concentrations in negative males. In contrast, breeding activity in positive rodents tended to be associated with lower testosterone concentrations and higher corticosterone levels. In spring 1999, concentrations of testosterone were significantly lower and those of corticosterone tended to be higher in positive breeding males than in negative ones. Stress induced by high population densities and among breeding animals is suggested to increase the risk of PUUV infection in adult male bank voles.Testosterone could play a role in the epidemiology of infection notably by enabling an extension of reproductive activities before peak years. A negative effect of corticosterone or PUUV infection on testosterone levels is also suggested.