Entamoeba histolytica and Entamoeba dispar infection in Mexican school children: genotyping and phylogenetic relationship.
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.
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Liliana
L
Rojas
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Patricia
P
Morán
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Alicia
A
Valadez
Research Unit of infectious Diseases, Pediatric Hospital, XXI Century Medical Center, Mexican Institute of Social Security (IMSS), Mexico City, Mexico.
Alejandro
A
Gómez
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Enrique
E
González
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Eric
E
Hernández
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Oswaldo
O
Partida
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Miriam
M
Nieves
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Marco
M
Gudiño
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico.
Ulises
U
Magaña
Research Unit of infectious Diseases, Pediatric Hospital, XXI Century Medical Center, Mexican Institute of Social Security (IMSS), Mexico City, Mexico.
Javier
J
Torres
Research Unit of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Dr Balmis No148 Col. Doctores, CP 06726, Mexico City, Mexico. cximenez@unam.mx.
Cecilia
C
Ximénez
D000293:Adolescent; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D017931:DNA Primers; D016054:DNA, Protozoan / Q000032:analysis; D004747:Entamoeba / Q000235:genetics / Q000302:isolation & purification*; D004748:Entamoeba histolytica / Q000235:genetics / Q000302:isolation & purification; D004749:Entamoebiasis / Q000453:epidemiology* / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D005260:Female; D005838:Genotype; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000453:epidemiology* / Q000469:parasitology; D008297:Male; D008800:Mexico / Q000453:epidemiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D015995:Prevalence
D017931:DNA Primers; D016054:DNA, Protozoan
E. dispar; E. histolytica; Frequency; Genotype; Patterns of transmission; Phylogenetic relationship