Occurrence and maintenance of hantavirus infections among rodent populations in their natural habitat--results of a field study from Podkarpackie province, Poland 2010-2012.

UNLABELLED: Human cases of hantavirus infection have been reported annually in Poland's Podkarpackie province, since 2007. In 2014 the number of cases reported significantly increased prompting a rise in studies focusing on the infection.

OBJECTIVE: The purpose of this study was to evaluate the prevalence, maintenance and the dynamics of hantavirus infection among rodent species, including the bank vole (Myodes glareolus) and yellow-necked mouse (Apodemus flavicollis) which act as reservoirs of hantavirus in the environment.

MATERIAL AND METHODS: Rodent capture was carried out on seven research grids in the Podkarpackie province, from summer 2010 to spring 2012. They were caught in live-capture traps used in accordance with the protocol CMR (Catch-Mark-Release). The population was estimated as MNA (Minimum Number Alive). Blood samples were collected for serological testing on live animals by puncture of saphenous vein. In order to determine the hantavirus infection we used ReaScan Ab-Dect Puumala IgG--Reagena® for bank voles, and for mice ELISA--Mouse Hanta Virus Test ELISA Kit (Version with Control Antigen Wells)--BioCat GmbH®. The relationship between age, gender, seasons, population size and prevalence of hantavirus infection was tested by Pearson's chi-squared test or Fisher's exact test and by calculating the Pearson's correlation coefficient.

RESULTS: A total of 854 rodents were captured: 222 bank voles, 592 yellow-necked mice, 4 common voles and 36 striped field mice. Of these, 564 were tested. The presence of specific anti-hantavirus was found in 9.7% of bank voles and 9.5% of yellow-necked mice. There was a statistically significant difference in the frequency of infection between the groups of male and female yellow-necked mice as well as in the groups of adult group in both species. The dynamics of spread of hantavirus infection was clearly evident in the studied area of Sanok. The correlation coefficient between the number of individuals caught and the prevalence of hantavirus infection in yellow-necked mice was -0,87 but for the bank vole it was 0,76.

SUMMARY AND CONCLUSIONS: The results of the study indicate that hantavirus infection among yellow-necked mice and bank voles are unevenly distributed in certain hot spots, vary over time, and are most in the spring season. In addition, differences observed in the dynamics of infection depended on the species of animal hosts. It would be advisable to conduct long-term study, which would allow for a risk assessment of the possibility of turning the spot located outbreaks into endemic area of hantavirus occurrence.