ON THE OCCURRENCE OF ECHINOCOCCOSIS MULTILOCULARIS IN HULUNBEIER PASTURE, NEI MONGOLIAN AUTONOMOUS REGION

The steppe pasture of Hulurnbeiheel, Inner Mongolia is one of three biggest pastures of the world, situated on 47-53° North Latitude and 115.5-126° East Longitude in North China. While it is a beautiful pasture with luxuriant growth of grasses, there exist endemic areas of a dreadful malady Echinococcosis. A number of infected persons including adult male and female as well as children coming to seek for surgical operations were recorded in regional hospital. The youngest child is only six years of age. The infections are, however, presumably sylvatic in nature occurring only where the wild animals exist.In the year 1985, from May to October, investigations were conducted on grasslands in four counties, nemely, West, Chen, Ghauwenke and East County. From our survey it was found that the rodent intermediate hosts of Echinococcus multilocularis are the voles, Microtus brandti Radde and Mongolian gerbil, Meriones unguiculatus Mile-Edwards.Of the 2,635 Microtus brandti examined, 64 (2.43%) were found infected with alveolar hydatids. The infection rates in different counties were found as follows: East County pasture 1.93% (29/1,505; of the 1,505 examined, 738 were newly born rats), West County pasture 3.8% (18/474), Ghauwenke County pasture 2.7% (6/222) and Chen County pasture 2.54% (11/ 434).Among 2,635 voles, all the newly born individuals, 738 in number, were found to be free of infection. Only 2 (0.78%) of the 418 young voles, 20 (2.36%) of the adolescent adults born in this year, and 42 (6.66%) of the over-wintering full grown voles examined were infected. The infection rates of over-wintering voles were 5.23%-14.29%. It is evident that Microtus brandti is the most important intermediate host of E. multilocularis in the region. However, another rodent, Meriones unguicolatus, has also been found to be infected with the alveolar hydatid, the infection rate was 16.67% (1/6).Six foxes of the species Vulpes corsac were captured from East County pasture and examined, 2 of them (33.33%) were found infected with adults of E. multilocularis. The number of worms is enormous, it reached more than ten thousands. Judging from the morphological features of protoscolice and adult of our specimens, they resemble closely to E. multilocularis sibiricensis (Rausch and Schiller, 1954) Vogel, 1957.Larval E. granulosus also occurs in cattle, sheep and camel in Hulurnbeiheel Pasture. The adults of this species also have been found in dogs.