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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.

SUBMITTER: Pattanawong U

PROVIDER: S-EPMC7924757 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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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.

Pattanawong Urassaya U Putaporntip Chaturong C Kakino Azumi A Yoshida Naoko N Kobayashi Seiki S Yanmanee Surasuk S Jongwutiwes Somchai S Tachibana Hiroshi H

PLoS neglected tropical diseases 20210218 2

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. Thirt ...[more]

PMID: 33600446

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Project description:This study aimed to determine the frequency of Entamoeba histolytica and Entamoeba dispar infection in school children in the community of Tlaltizapan, in order to understand the dynamics of infection within the school and family spheres of this population. Amoebiasis is an unsolved public health problem and an endemic disease in Mexico. The incidence rate varies depending on the state; the most affected states show the highest numbers of new cases of amoebiasis per year. Previously, we reported the molecular frequency of infection with E. histolytica and/or E. dispar in other rural communities of the state of Morelos.Children from 3 schools were studied to estimate the frequency of intestinal parasites through microscopic examination of fresh stool samples. The number of studied individuals were 309 school children. The molecular characterization of E. histolytica or E. dispar was carried out by Polymerase Chain Reaction (PCR) using species-specific primers to amplify short tandem repeats (STR) in non-coding sequences associated with the tRNA gene; the amplified fragments were sequenced and analyzed.Eight different genotypes were obtained from E. dispar isolates with the molecular marker NKD3-D5. None of the cases in which the species E. histolytica was detected developed symptoms attributable to an invasive process of disease. Moreover, the parasitized condition appeared to have no significant impact on the development or nutritional status of affected children. Genotype 1, which corresponds to the reference strain E. dispar SAW760, considered a non-pathogenic amoeba, was the most prevalent.The comparison of the genotypes of Entamoeba species did not show a correlation between children and their relatives. In this community, the species Entamoeba dispar genotype 1 was the most widespread. Based on the indicators of growth, development and nutrition status, the studied community seems to be reasonably adapted to constant exposure to intestinal parasites, since there were no evidences of a serious impact of the parasitized condition on the children's health.

Project description:BackgroundAmebiasis is a protozoal infection caused by Entamoeba histolytica, while the morphologically indistinguishable E. dispar is considered as non-pathogenic. Polymerase chain reaction (PCR) assays are necessary to differentiate both species. The most common clinical presentations of E. histolytica disease are amebic colitis and amebic liver abscess, but asymptomatic infection is also possible. We assessed the frequency and pattern of clinical symptoms and microscopic features in travelers/migrants associated with E. histolytica intestinal infection and compared them to those found in individuals with E. dispar infection.MethodsWe conducted a retrospective study at the travel clinic of the Institute of Tropical Medicine, Antwerp, Belgium on travelers/migrants found from 2006 to 2016 positive for Entamoeba histolytica/dispar through antigen detection and/or through microscopy confirmed by PCR. All files of individuals with a positive PCR for E. histolytica (= cases) and a random selection of an equal number of Entamoeba dispar carriers (= controls) were reviewed. We calculated the sensitivity, specificity and likelihood ratios (LRs) of clinical symptoms (blood in stool, mucus in stool, watery diarrhea, abdominal cramps, fever or any of these 5 symptoms) and of microscopic features (presence of trophozoites in direct and in sodium acetate-acetic acid-formalin (SAF)-fixed stool smears) to discriminate between E. histolytica and E. dispar infection.ResultsOf all stool samples positive for Entamoeba histolytica/dispar for which PCR was performed (n = 810), 30 (3.7%) were true E. histolytica infections, of which 39% were asymptomatic. Sensitivity, specificity and positive LRs were 30%, 100% and 300 (p 0.007) for presence of blood in stool; 22%, 100% and 222 (p 0.03) for mucus in stool; 44%, 90% and 4.7 (p 0.009) for cramps and 14%, 97% and 4.8 (p = 0.02) for trophozoites in direct smears. For watery diarrhea, fever and for trophozoites in SAF fixated smears results were non-significant.ConclusionsE. histolytica infection was demonstrated in a small proportion of travelers/migrants with evidence of Entamoeba histolytica/dispar infection. In this group, history of blood and mucus in stool and cramps had good to strong confirming power (LR+) for actual E. histolytica infection. Trophozoites were also predictive for true E. histolytica infection but in direct smears only.

Project description:BACKGROUND:Utilization of oral health services has been low among rural populations in Thailand, especially for minority ethnicity populations living along the borders. The aim of this study was to increase understanding of the determinants of the underutilization of oral health services among these populations. METHODS:A qualitative study using in-depth interview and semi-structured interview was conducted among participants of Karen ethnicity living in Mae Tan Sub-district, Thasongyang District, Tak Province, Thailand. The interviews focused on exploring the participants' perceptions of oral health problems, oral health and hygiene, and oral health-seeking behaviors. The verbatim-transcribed interviews were analyzed using thematic analysis. RESULTS:A total of 101 participants (50 adults and 51 children) with a Karen ethnic background took part in the interviews. Most participants could not identify oral health problems and did not perceive dental disease as a problem unless there was severe pain that could not be relieved by painkillers. The Karen ethnic community worked as subsistence farmers, and their busy daily activities consisted of farming, going to the forest to hunt and gather, performing housework, and taking care of their children. Dental health was given a lower priority compared with general health. The perceived value of primary teeth was low, which was identified as an underlying factor resulting in delayed oral health care seeking among this population. The participants had relied on self-care throughout their lifetimes, using either traditional medicines or modern painkillers to relieve toothaches. Fear of dental procedures among children was also described as a barrier to seeking dental health care. CONCLUSIONS:This study found that the lifestyle and traditions of Karen people living in this area influence their oral health care and hygiene activities as well as their health-seeking behaviors. Further research should emphasize how to improve oral health promotion by providing necessary services and health education appropriately to Karen ethnic populations living along the Thai-Myanmar border.

Dataset Information

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.

Publications

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.

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