Prevalence of parasitism among students of the Karen hill-tribe in Mae Chame district, Chiang Mai province, Thailand.

Infection caused by intestinal parasites is still a common health problem in a poor-hygiene population especially for children in developing countries. A cross-sectional study was conducted among 781 Karen students (age: 3 to 19, males: 325, females: 456) to determine the current status of intestinal parasitic infections in a mountainous area in the North of Thailand. The study was drawn from three schools in the Doi Inthanon region, in Mae Chame district of Chiang Mai province, from December 2002 to June 2003. The techniques used for the diagnosis were: stool concentration by using the 'formalin-ether' technique and perianal region examination by using the 'Scotch-tape' technique. The average rate of intestinal parasites for the group tested using the stool concentration technique was 42.06% (male: 46.87%, females: 38.82%); and 22.66% (males: 28.92%, females: 18.20%) when using the Scotch-tape technique.Among helminth-infected individuals, enterobiasis was found at the highest prevalence (15.49%). Other common infections were ascariasis (9.78%), trichuriasis (5.90%) and hookworm infection (2.20%). Strongyloildiasis was found only in 0.92%. For protozoa infection, the major cause is the non-pathogenic species "Entamoeba coli" (27.68%). The other non-pathogenic protozoa (Endolimax nana, Chilomastix meslini and Iodamoeba butschlii) had a low prevalence from ranged 0.18%-4.79%. The prevalence of pathogenic Giardia lamblia infection was 2.21%. Entamoeba histolytica infection was found in only one case. Based on the two techniques used, the results from the Scotch-tape provided a higher sensitivity for the detection of Taenia spp. and Enterobius vermicularis eggs. Drug treatment was given to all the infected students. School-based health education should be implemented in order to prevent and control the infections.