Abstract
Background
Epidemiological studies carried out using culture or microscopy in most of the amoebiasis endemic developing countries, yielded confusing results since none of these could differentiate the pathogenic Entamoeba histolytica from the non-pathogenic Entamoeba dispar and Entamoeba moshkovskii. The Northeastern part of India is a hot spot of infection since the climatic conditions are most conducive for the infection and so far no systemic study has been carried out in this region.
Methodology/Principal Findings
Following a cross-sectional study designed during the period 2011–2014, a total of 1260 fecal samples collected from the Northeast Indian population were subjected to microscopy, fecal culture and a sensitive and specific DNA dot blot screening assay developed in our laboratory targeting the Entamoeba spp. Further species discrimination using PCR assay performed in microscopy, culture and DNA dot blot screening positive samples showed E. histolytica an overall prevalence rate of 11.1%, 8.0% and 13.7% respectively. In addition, infection rates of nonpathogenic E. dispar and E. moshkovskii were 11.8% (95% CI = 10.2, 13.8) and 7.8% (95% CI = 6.4, 9.4) respectively. The spatial distributions of infection were 18.2% (107/588) of Assam, 11.7% (23/197) of Manipur, 10.2% (21/207) of Meghalaya, and 8.2% (22/268) of Tripura states. Association study of the disease with demographic features suggested poor living condition (OR = 3.21; 95% CI = 1.83, 5.63), previous history of infection in family member (OR = 3.18; 95% CI = 2.09, 4.82) and unhygienic toilet facility (OR = 1.79; 95% CI = 1.28, 2.49) as significant risk factors for amoebiasis. Children in age group <15 yr, participants having lower levels of education, and daily laborers exhibited a higher infection rate.
Conclusions/Significance
Despite the importance of molecular diagnosis of amoebiasis, molecular epidemiological data based on a large sample size from endemic countries are rarely reported in the literature. Improved and faster method of diagnosis employed here to dissect out the pathogenic from the nonpathogenic species would help the clinicians to prescribe the appropriate anti-amoebic drug.
Most epidemiologic studies in developing countries carried out for amoebiasis is either based on microscopy alone or culture/ microscopy used as a screening tool, have poor sensitivity and specificity and thus fails to figure out its true magnitude. The purpose of this study was to assess the true prevalence of amoebiasis in selected North Eastern states of India using DNA based screening technique followed by PCR assay for species discrimination. In addition, PCR assay confirmed that only 55.8% of the samples, resembling E. histolytica by microscopy, were true E. histolytica, implying that remaining 44.2% of so-called infections were due to other nonpathogenic Entamoeba spp. We found a higher prevalence of amebiasis (13.7%) using DNA dot blot screening compared to conventional microscopy and culture based screening. Poor living condition, previous history of infection in a family member, unhygienic toilet facility, children in age group <15 yr, participants having lower levels of education and daily laborers were identified as significant risk factors for amoebiasis. Thus, the techniques like DNA dot blot hybridization and PCR based detection adopted in the present study over and above the conventional screening methods can reduce misdiagnosis of the disease appreciably from the population living in this endemic area.
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