Surveillance of Hemorrhagic Fever with Renal Syndrome in Yunnan Province, China, in 2004

Objective To understand epidemiological characteristic of hemorrhagic fever with renal syndrome(HFRS) and to offer a guidance of HFRS control and prevention in Yunnan province. Methods Collecting the data of cases of HFRS in Yunnan province and collecting human sera and the lung tissue and sera of rodents in the surveillance counties and detecting the antibody and antigen of hantavirus. Results The 55 cases and 2 deaths had been reported in Yunnan province in 2004. The incident rate was 0.13/100 000 and the case fatality rate was 3.64%. The main attacked areas were in Dali prefecture, Kunming city, Honghe prefecture, and Chuxiong prefecture. The 10 species of 803 rodents had been captured and the 314 rodent sera and 313 human sera had been collected in Luxi, Xundian and Yongsheng counties which were the surveillance areas. The rodents of Rattus norvegicus and Rattus flavipectus were the dominant species in human living areas and the rodents of Apodemus agrarius was the dominant species in these fields. The hantavirus carrying rate was 3.89% ( 26/668) in rodents and the virus carrying rodents were Rattus norvegicus, Rattus flavipectus,Mus musculus, Apodemus agrarius, Suncus murinus and Blarinella guadraticauda. The positive rate of the antibody in human and rodent was 3.50% and 2.24% respectively. The 16 species of 896 rodents had been captured in 10 counties (or city) of the western Yunnan province and the rodents of Eothenomys miletus was the dominant species. The hattanvirus carrying rate was 3.01% ( 27/896) in rodents and the rodents of virus carrying were R.norvegicus, R.flavipectus, M.musculus, R.nitidus, A.agrarius, S.murinus and B.guadraticauda. Conclusion There are the Rattus foci with the hosts of the main rodents of R.norvegicus and R.flavipectus and there are the Apodemus foci with the host of the main rodents of A.agrarius and E.miletus in the surveillance areas too. The incident had been increasing as the density of rodents and the rate of infected virus in the rodents was going up.