Southeast Asian J Trop Med Public Health

A cross-sectional study was performed to evaluate the risk factors of Blastocystis hominis infection in the Thai army population of the 11 Infantry Division, Chachoengsao Province, Thailand. 201 army personnel and their family members were enrolled in this study. Intestinal parasitic infections in this population were assessed by stool examination using simple smear, formalin/ether technique and Kato-thick smear. Approximately one third of the specimens were positive for one or more intestinal parasites. With the prevalence of 21.9%, B. hominis was the most common intestinal parasite found in this population. Our data indicated that blastocystosis in this army population was significantly linked to the quality of drinking water. After being adjusted for potential confounders, consuming neither filtered nor boiled water was independently associated with blastocystosis. Correspondence: Tel/Fax: 66-2-245-8331 BLASTOCYSTOSIS IN THAILAND Vol 31 No. 1 March 2000 113 437, 70 and 97 were privates, non-commissioned officers, commissioned officers and family members, respectively. The army members routinely exercise within the area of this army division. While most of the officers and their families were local people, almost all privates in this division came from northeastern Thailand and had to serve in the army for 2 years. The majority of this community were privates in the age range 20 to 30 years. There were 201 members of this army community who voluntarily enrolled in this study. The water supply of the 11 Infantry Division was mainly tap water and rain water with or without further treatment. Privates were living together in the buildings and consuming water that was available for them, either tap or rain water, while officers and their families were living in separate houses and able to choose any source of drinking water and also its treatment. Stool specimens were collected and examined immediately for B. hominis by simple smear preparation. Saline and lugol iodine preparation of each sample were examined under 10x and 40x magnification. Each stool sample was preserved in 10% formalin solution in order to perform a formalin/ ether concentration technique. Trichrome staining was also done to confirm the suspected specimens. Kato-thick smear technique was used to identify intestinal helminths in every specimen. To determine the risk factors of B. hominis infection in this community, individual was asked to fill the health assessment questionnaires concerning age, rank, sex, type of water consumed, history of diarrhea and other gastrointestinal symptoms. Individual data was compared to his/her result of stool examination. Univariate analysis was performed using Epi Info version 6.04b. Odds ratios with 95% confidence intervals and p-values were calculated to compare outcomes among study groups. Logistic regression using SPSS for Windows version 7.5.2 was performed for multivariate analysis to assess the independent association of risk factors and B. hominis infection.