Analysis of D-A locus of tRNA-linked short tandem repeats reveals transmission of Entamoeba histolytica and E. dispar among students in the Thai-Myanmar border region of northwest Thailand

Abstract

Intestinal parasitic infections, including those caused by Entamoeba species, are a persistent problem in rural areas of Thailand. The aims of this study were to identify pathogenic Entamoeba species and to analyze their genotypic diversity. Stool samples were collected from 1,233 students of three schools located in the Thai-Myanmar border region of Tak Province, Thailand. The prevalence of Entamoeba infection was measured by polymerase chain reaction (PCR) using species-specific primers. Thirty-one (2.5%) positive cases were detected for E. histolytica, 55 (4.5%) for E. dispar, and 271 (22.0%) for E. coli. Positive samples for E. histolytica and E. dispar were exclusively obtained from a few school classes, whereas E. coli was detected in all grades. No infections caused by E. moshkovskii, E. nuttalli, E. chattoni, and E. polecki were detected in the students studied. The D-A locus of tRNA-linked short tandem repeats was analyzed in samples of E. histolytica (n = 13) and E. dispar (n = 47) to investigate their diversity and potential modes of transmission. Five genotypes of E. histolytica and 13 genotypes of E. dispar were identified. Sequences of the D-A were divergent, but several unique genotypes were significantly prevalent in limited classes, indicating that intra-classroom transmission has occurred. As it was unlikely that infection would have been limited within school classes if the mode of transmission of E. histolytica and E. dispar had been through the intake of contaminated drinking water or food, these results suggest a direct or indirect person-to-person transmission mode within school classes. Positive rates for three Entamoeba species were 2-fold higher in students who had siblings in the schools than in those without siblings, suggesting that transmission occurred even at home due to heavy contacts among siblings.

Prevalence of Intestinal Protozoan Parasites Among 29,968 School Children in Africa: A Systematic Review and Meta-Analysis

“…The pooled prevalence rate of E. histolytica/ dispar in this metaanalysis was 13.3%, which is consistent with the 14.09% rate reported in Ethiopia [4] and 12.1% in the Philippines [78]. However, the prevalence rate in the present study was lower than that in studies conducted in Malaysia (20.4%) [79], Yemen (16.4) [80] and Tanzania 15% [81] but higher than that in studies in Bangladesh (3.83%) [82] and Thailand (3.7%) [83].…”

“…Similar infection rate (11.0%) was reported from Brazil [84], and a considerably higher prevalence rate was detected in Nepal (46.8%) [85]. Meanwhile, the infection rate in PLOS NEGLECTED TROPICAL DISEASES Bangladesh (6.01%) [82] and Thailand (4.9%) [83] was lower than the present finding. The variations in prevalence rates of E. histolytica/dispar and Giardia spp.…”

Prevalence of intestinal protozoan parasites among school children in africa: A systematic review and meta-analysis

“…histolytica/ dispar in this meta-analysis was 13.3%, which is consistent with the 14.09% rate reported in Ethiopia [ 4 ] and 12.1% in the Philippines [ 78 ]. However, the prevalence rate in the present study was lower than that in studies conducted in Malaysia (20.4%) [ 79 ], Yemen (16.4) [ 80 ] and Tanzania 15% [ 81 ] but higher than that in studies in Bangladesh (3.83%) [ 82 ] and Thailand (3.7%) [ 83 ].…”

“…Similar infection rate (11.0%) was reported from Brazil [ 84 ], and a considerably higher prevalence rate was detected in Nepal (46.8%) [ 85 ]. Meanwhile, the infection rate in Bangladesh (6.01%) [ 82 ] and Thailand (4.9%) [ 83 ] was lower than the present finding. The variations in prevalence rates of E .…”