Surveillance analysis of HFRS in Jiangsu in 2005

Objective The study was conducted to analyze the surveillance results of hemorrhagic fever with renal syndrome (HFRS) in Jiangsu in 2005 to better understand the human epidemic and virus carrier animals for more effective control and prevention of HFRS. Methods The provincial epidemic surveillance and reporting materials and annual summary were collected for epidemiological analysis. The density of host animals was surveyed by rattrap placed in house and field,and positive rate of antigen and antibody was calculated and compared by testing samples collected from host animals and local residents. Results The HFRS epidemic in human was stable with a declining trend in Jiangsu in 2005,while the epidemic in three surveillance spots showed different degrees of declining compared with year 2004. However,the peak of epidemic altered significantly as the predominant peak presented in autumn and winter. Silent infection rate in general population was 11.9%,though the coincidence of diagnosis among the cases was only 42.9%. The overall density of rats was 2.3%,indoor predominant species being Mus musculus,outdoor being Cricetulus barabensis. The positive rate of antigen was 1.4%,antibody 8.1%. Conclusion The declining epidemic was relatively correlated with the lowering rat density and increasing silent infection rate in population (vaccination). Autumn-winter peaks were correlated with high virus carrier rate of rats in particular regions. It is required to strengthen the epidemic Surveillance and mouse-killing in specific regions to consolidate the prevention and control of HFRS.