[Study on geographic epidemiology of epidemic hemorrhagic fever (EHF) in China]

The distribution, epidemic intensity and the focus type of EHF at county's level in China was studied by the method of discriptive, serological and geographic epidemiology. The EHF foci distributed in 1,257 counties within 25 provinces (cities, autonomous regions) by 1986, 633 of them were found before 1980 and the other 624 after it. The epidemic area have extended nearly twice in the last years. The extension of rattus type focus was most significant. The number of focus of Rattus type increased from 20 counties in 1980 (account for 3.73% of total foci) to 288 in 1986 (26.77%); the mixed type also enlarged from 98 (18.28%) to 267 (24.81%); while the Apodemus type was relatively steady. More than 250,000 small animals were captured and tested in this research. 4 orders 8 families and 37 species were found carrying EHF virus antigen. The research pointed out that the main kinds of the reservoir were limited. In addition, the animals which carry EHF virus were found also in 111 non-case-reported counties, so these areas could be a potential EHF's foci. The relationship between the distribution of EHF focus (especially Apodemus type) and natural geographic factors, such as the physical features of a place, precipitation and water system etc, was analysed. The preventive strategies and suggestions were also discussed.