Epidemiological Investigation of Parasitic Infection of Schoolchildren from Six Elementary Schools in Sakon Nakhon Province, Thailand.

We conducted an epidemiological study of intestinal parasitic infection in 572 schoolchildren aged 4 to 12 years old from six elementary schools in Sakon Nakhon Province, Thailand from June 2013 to August 2014. We collected fecal, blood, and urine samples to investigate parasitic infection and conducted a questionnaire survey. Soil samples were examined for egg contamination. Fecal examination, using the formalin-ether sedimentation method, revealed that 39% of schoolchildren were infected with eight genera and eight species of parasites; three nematodes, two trematodes, one cestode, and two protozoa. Prevalence rates across the six schools (schools A through F) were: A (13%), B (15%), C (53%), D (11%), E (20%), and F (43%). Schools C and F showed significantly higher prevalence rates than the other schools (p<0.05). In school C, Necator americanus was detected in 49% of schoolchildren tested, while in school F a high prevalence of Opisthorchis viverrini and Heterophyes heterophyes, at a rate of 23% and 21%, respectively, was detected. The questionnaire survey revealed that health, hygiene practices and awareness were poor in school C. However, school F showed high levels of cognizance and practices relating to the prevention of infection. The schoolchildren ate a staple diet of undercooked river fish and the results revealed a high rate of fish-borne parasites. Soil samples showed Toxocara sp. contamination in and around the campus. Toxocara antibodies were detected in over 6% of schoolchildren. The use of urine samples, as opposed to serum samples, was found to be effective for antibody testing.