PREVALENCE AND RISK FACTORS OF BLASTOCYSTIS SP. INFECTION AMONG PRIMARY SCHOOL CHILDREN IN A RURAL COMMUNITY, CENTRAL THAILAND

Abstract

Background:Blastocystissp., a protozoan parasite, has been globally reported as one of the most common intestinal parasitic infections in humans. Water transmission plays an important role for the route of transmission of this organism to humans. Objectives:To determine the prevalence and risk factors of Blastocystissp.infection among schoolchildren in a rural community, central Thailand. Materials and Methods:In November 2015, schoolchildren from four primary schools (School A, B, C and D) at a rural community of Sanamchaikate district, Chacherngsao Province, central Thailand were enrolled into the study. Stool samples collected from participants were examined using wet preparation, phosphate buffered saline-ethyl acetate and Kato-Katz techniques. Short-term cultivation for Blastocystis sp. was performed using Jone’s medium supplemented with 10% horse serum. Strongyloides stercoralis was also detected using agar plate culture technique. Results:A total of 501 school children were analyzed. The mean age at diagnosis was 9.996±1.59years. The prevalence of overall parasitic infections was 17.8% and were diagnosed as follows: Blastocystis sp. in 64 participants (12.8%), Giardia duodenalis (1.4%), Entamoeba coli (1.0%), Opisthorchis viverrini(0.8%), Enterobius vermicuralis (0.6%), and Strongyloides stercolaris (0.4%). A significantly increased risk of Blastocystis sp.infection was found in children studying at the School B, C and A when compared with those studying at School D (p =0.001, OR =4.36, 95% CI =1.83-10.39, p =0.032, OR= 2.89,95% CI =1.10-7.64, and p =0.033, OR =2.2, 95% CI =1.06-4.54, respectively). Drinking water was suspected to be the source of transmission. However, screening by PCR at the 18S rRNA gene for Blastocystis sp. could not detect the parasites from any sources of drinking water samples collected from the four schools. Conclusion:Themost predominant intestinal protozoa infection in the study school children was Blastocystis sp. The high prevalence of protozoa infection could reflect the hygienic conditions of the children. Thus, health education and the control of intestinal parasitic infections are necessary to these children.