Surveillance for hemorrhagic fever with renal syndrome and evaluation of immunization effect in Gaoan, Jiangxi, 2005-2012

Objective To understand the incidence trend and epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in Gao'an county, Jiangxi province, from 2005 to 2012 and provide evidence for the development of HFRS prevention and control strategies. Methods Descriptive epidemiological analysis was conducted on the incidence data of HFRS during this period, which were collected from national disease reporting information system, and the host surveillance data. Rats were captured by using traps. The Hantaan virus carriage in rats was detected by using immunofluorescent assay and the serum Hantaan virus antibodies in rats were detected by using ELISA. Results From 2005 to 2012, a total of 584 HFRS cases were reported including 30 deaths. The average annual incidence rate was 8.65/lakh, the mortality was 0.44/lakh and the case fatality rate was 5.14%. The annual incidence was relatively stable with two peaks during a year. Most cases were adults, and the majority of them were farmers. The incidence rate in males was higher than that in females (2=67.42, P=0.00). The antibody positive rate in healthy population was 29.26% after supplementary HFRS immunization (2009-2012), which was significantly higher than that before HFRS immunization (2005-2008). The average density of rat was 2.54%, but it increased significantly in 2012. The major indoor host was Rattus norvegicus, while the major outdoor host was Rattus losea. The average index of rat with virus was 0.0198 and increased significantly during 2011-2012. Conclusion The risk of HFRS in Gao'an increased significantly from 2011 to 2012. It is suggested to conduct supplement HFRS immunization and evaluate the effect of HFRS immunization.