A SURVEY ON INTESTINAL PARASITE INFECTION OF JAPAN OVERSEAS COOPERATION VOLUNTEERS (1981-1982)

The stool examinations on long-term visiters to developing countries were carried out to investigate the epidemiology of parasitosis imported to Japan. The subjects of the investigation were 716 Japan Overseas Cooperation Volunteers who returned in 1981-1982. The infection rates of parasitosis among the volunteers before departure (Yamaura et al., 1981) were compared as controls of this survey. Formalin-ether sedimentation method, zinc sulfate centrifugation-flotation method and Harada & Mori's test-tube cultivation method were used for stool examination. Rizopoda was identified by Hydenhain's iron-hematoxylin staining.The results are summarized in Table 1 and Table 2 : 1) The infection rates among returned volunteers (28.4% in 1981 and 23.2% in 1982) were much higher than the rate before departure (2.5%, 5/198) (Table 1). No relation between infection rate and sex of the volunteers was recognized.2) The highest infection rate was found for Giardia lamblia (12.6%, 90/716). Entamoeba histolytica was observed in 2.2 per cent (16/716). High infection rate of E. histolytica was observed among the volunteers returned from Ghana (14.7%, 5/34). More than two species of parasites were found in 20.7 per cent of positive cases (Table 2).3) The infection rates of volunteers returned from Bangradesh and from Nepal were 68.0 per cent and 56.1 per cent respectively.These two rates were found to be significantly higher than that from other 24 countries. The ratio of helminth infection to protozoa infection in African and Central-and South American countries was lower than that in Asian and Oceanian countries (Table 2).