Molecular Detection of the Carriage Rate of Four Intestinal Protozoa with Real-Time Polymerase Chain Reaction: Possible Overdiagnosis of Entamoeba histolytica in Nigeria

Abstract

Abstract. Diarrhea remains the second largest killer of children worldwide, and Nigeria ranks number two on the list of global deaths attributable to diarrhea. Meanwhile, prevalence studies on potentially diarrheagenic protozoa in asymptomatic carriers using molecular detection methods remain scarce in sub-Saharan countries. To overcome sensitivity issues related to microscopic detection and identification of cysts in stool concentrates, real-time polymerase chain reaction (PCR) was used to analyze genomic DNAs extracted from stool samples from 199 healthy school children for Entamoeba histolytica, E. dispar, Giardia intestinalis, and Cryptosporidium. Questionnaires were administered for epidemiological data collection. E. histolytica was not detected in any of the samples, whereas Giardia (37.2%), E. dispar (18.6%), and Cryptosporidium (1%) were found. Most of the children sourced their drinking water from community wells (91%), while the majority disposed of feces in the bush (81.9%). Our study is the first to use real-time PCR to evaluate the epidemiology of E. histolytica, Giardia, and Cryptosporidium in Nigeria where previous studies using traditional diagnostic techniques have suggested higher and lower carriage rates of E. histolytica and Giardia, respectively. It is also the first study to accurately identify the prevalence of common potentially diarrheagenic protozoa in asymptomatic carriers in sub-Saharan Africa.

Evaluation of the BD MAX Enteric Parasite Panel for the detection of Cryptosporidium parvum/hominis, Giardia duodenalis and Entamoeba histolytica

“…• infecting species of the parasite E. histolytica and E. dispar are morphologically indistinguishable by light microscopy 3 . Of the two species, only E. histolytica is capable of causing invasive disease.…”

Epidemiological Aspects of Blastocystis Colonization in Children in Ilero, Nigeria

“…Study site, study population, acquisition of sociodemographic data, and DNA extraction is described in the recent articles by Efunshile and others. 13,14 In brief, samples were collected in Ilero, Nigeria, from preschool nursery children and schoolchildren between 2 and 14 years of age. Demographic data available for analysis included data on gender, religion, toilet facilities, and water sources.…”

“…In this study, 199 genomic DNAs, previously extracted directly from stool from 199 unique children by use of the QIAamp DNA Stool Mini Kit (Qiagen GmBH, Hilden, Germany) and screened for Entamoeba histolytica, Entamoeba dispar, Giardia intestinalis, and Cryptosporidium spp. by real-time PCR, 13 were all screened for Blastocystis using the real-time PCR method previously described, and cycle threshold (Ct) values were recorded for each positive sample. 9 Subsequently, all PCR-positive samples were subtyped by barcoding according to Scicluna and others 12 and Stensvold.…”

“…To further this understanding, knowledge on the prevalence and distribution of STs in the background population in different parts of the world is important for reference. In this study, we surveyed a cohort of Nigerian children 13 for Blastocystis with a view to elucidating aspects of its epidemiology, including prevalence and distribution of STs and ST alleles in a cohort of individuals representing the background population.…”

Use of real-time polymerase chain reaction to identify Entamoeba histolytica in schoolchildren from northwest Mexico

“…For example, in southwestern Nigeria, 199 stool samples of children (6-14 years of age) from a semirural community were analyzed by real-time PCR, and none was positive for E. histolytica [25]. Similarly, not a single positive sample was detected among 363 stool samples of primary schoolchildren from various regions of Ethiopia, also analyzed by real-time PCR.…”