Monitoring study on hemorrhagic fever with renal syndrome (HFRS) in Hunan Province

Objective The present study was conducted to find out the epidemiological characteristics and tendency of hemorrhagic fever with renal syndrome (HFRS) during the years from 2002 to 2005 in Hunan Province, so as to formulate specific pertinent prevention and control measures. Methods Descriptive epidemiologic methods were used to analyze the epidemic situation: at the 5 monitoring sites, the blood serum samples of healthy people were collected to investigate the covert infections; the night trapping method was used to capture the indoor and outdoor small animals; the HV antigens and antibodies were examined by immunofluorescence assay (DFA, IFA) and enzyme-linked immunosorbent assay (ELISA), and they were classified by monoclonal antibody; the quality monitoring was conducted to the laboratory rats; and the suspected cases received examinations of dynamic HV-IgG/IgM antibodies. Results During the years from 2002 to 2005, the incidence of HFRS declined significantly in Hunan Province. And HFRS concentrated from November to the following January, and the lower peak was at August and September. There were high incidences in Xiangtan, Changsha City, Shaoyang City, Yiyang and Huaihua City; the cases were mainly young male farmers, and the sex ratio of the incidence was 2.05∶1. The laboratory positive rate of suspected cases was 26.84%. The interanimal investigation showed that the total density of rats was 3.4%, with indoor density 3.31% and outdoor 3.59%; Apodemus agrarius was advantageous host in the field while rattus norvegicus was advantageous host indoor. The differences of the capture rates and viruliferous rate at the monitoring sites were of statistical significance. Apodemus agrarius mainly carries Hantavirus I and Rattus norvegicus mainly carries Hantavirus II. The covert rate of healthy populations was 5.88%. And the positive rate of HV antibodies of laboratory rats was 1.72%. Conclusion Hunan Province is a mixed type of hemorrhagic fever with renal syndrome (HFRS) epidemic area. To effectively prevent and control the disease of hemorrhagic fever with renal syndrome (HFRS), the monitoring and prevention measures should be reinforced and the deratization and preventive inoculation work should be strengthened.