Surveillance analysis of human hemorrhagic fever with renal syndrome in Hunan from 2002 to 2005

Objective The study was conducted to explore the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS),the dynamic variation of serological antibody and the silent infection rate of people in Hunan for further prevention and control of HFRS. Methods The epidemic and laboratory data in Hunan from 2002 to 2005 was collected for epidemiological analysis. The silent infection rate among healthy people was calculated by indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). IgM,IgG detection and further typing were conducted for HFRS suspected sera delivered in the province. Results 3763 cases were reported from 2002 to 2005 in the whole province,of which 17 patients died,and the annual incidence rate and the fatality rate were 1.42/lakh and 0.0064/lakh,respectively. Most infections had occurred from November to January of next year. The high incidence areas were Xiangtan,Changsha,Shaoyang,Huaihua,and Yiyang prefecture,the number of cases in the five prefectures accounting for 56.39%. Farmers were the most affected group. The ratio of male to female was 2.03∶1. The incidence age ranged mainly from 16 to 55. From 2002 to 2005,the incidence showed a declining trend of 66.14%,and 26.82% suspected cases were confirmed by laboratory tests. 86.81% of the confirmed cases presented low liter or negative IgM and IgM at early stage. The silent infection rate among healthy people was 5.88%. Conclusion Hunan is a mixed epidemic area of HFRS where only few suspected cases have been confirmed and the silent infection rate is high. It is necessary to strengthen the preventive approaches combined with mouse-killing and vaccination for risk people. Laboratory diagnosis should be enhanced and clinical diagnosis improved for better prevention and control of HFRS.