OBJECTIVEIn order to better understand the epidemiological features of Hantviruses in Inner Mongolia.

METHODSEpidemiological surveillance data during the period of the past 52 years were analyzed. An epidemiological survey was carried out in the main epidemic areas in 2005.

RESULTSA total of 8310 hemorrhagic fever with renal syndrome (HFRS) cases were reported in Inner Mongolia from 1955 to 2006, and distributed in 61 counties. HFRS cases were mainly distributed in the east part of Inner Mongolia before 1990. However, HFRS cases had occurred in the middle and western parts since 1990. Hulunbeier prefecture, from the eastern part of Inner Mongolia, had been the most severe area being hit by HERS since the first outbreak in 1955, with 7369 cases reported over the past 52 years, and accounted for 88.68% of the total cases in the whole autonomous region. Although no HFRS cases had been reported before 1999 in Bayannaoer which located in the western part of Inner Mongolia, a total of 95 cases were reported in 2005. Hantavirus antigens had been detected in 11 species of rodents so far,including Apodemus agrarius, Rattus norvegicus, Mus Musculus, Cricetulus barabensis, meriones meridianus, Microtus maximowiczii , Clethrionomys rutilus, Apodemus peninsulae, Phodopus roborvskii, Dipus sagitta and Allactaga sibirica.

CONCLUSIONResults suggested that the epidemics might remain at a relatively high level in the years to come in Inner Mongolia. Furthermore, there might be other types of Hantaviruses in addition to the already identified Seoul viral type in this area.