Prevalence of Intestinal Parasitic Infections, Genotypes, and Drug Susceptibility of Giardia lamblia among Preschool and School-Aged Children: A Cross-Sectional Study in Thailand

Abstract

This study aimed to estimate the prevalence of intestinal parasitic infections in children and assess the drug susceptibility and genotypes/assemblages of Giardia lamblia in Thailand. This cross-sectional study was conducted among children aged 3-12 years in Sangkhlaburi District, Kanchanaburi Province, Thailand, between 25 September 2017 and 12 January 2018. Parasites were identified by stool microscopic examination, cultivation of intestinal parasitic protozoa, and enzyme-linked immunosorbent assay (ELISA). Drug susceptibility and genotype of G. lamblia were performed, respectively, by a resazurin assay and Triosephosphate Isomerase A and B genes using modified primers and probes. Among the 661 participants, 445 had an intestinal parasitic infection, resulting in a prevalence of 67.32% (95% CI: 63.60-70.89%). Blastocystis hominis was the most prevalent protozoa infection (49.32%; 95% CI: 45.44-53.22%), while Ascaris lumbricoides was the most prevalent helminth infection (0.91%; 95% CI: 0.33-1.97%). The prevalence of G. lamblia was 17.40%, with genotype B being the most common. According to our study, intestinal parasitic infections were commonly found in Thai children. G. lamblia was the most common pathogenic protozoa infection identified and exhibited less susceptibility to metronidazole compared to furazolidone and mebendazole.

Keywords: Giardia lamblia; cross-sectional study; drug susceptibility; genotype; intestinal parasite; prevalence.

Figure 1

Location of the study sites at Bann Huay Malai, Border Patrol Police United Bank Bangkok, and United Christian schools, Sangkhlaburi District, Kanchanaburi Province, Thailand.

Figure 2

Drug susceptibility test of G. lamblia isolates from 10 volunteers. The data are expressed as IC₅₀ (µM) ± SD of three independent experiments. X-axis describes individual subjects: (A) Metronidazole; (B) Furazolidone; (C) Mebendazole. The subjects designated as A–J in the X-axis were de-identified from specimen ID without linking to the identifying subject information.