Distribution and Differential Diagnosis ofEntamoeba HistolyticafromEntamoeba Disparby the PCR-RFLP Method in Central Iran

Abstract

Background: Entamoeba histolytica and Entamoeba dispar are two morphologically indistinguishable human protozoan parasites that are genetically distinct species. The potential invasive pathogenic Entamoeba histolytica and non-invasive parasite Entamoeba dispar can be differentiated by molecular and other methods. We used polymerase chain reaction (PCR) to determine the ratio of the two species in a population in Tehran and Karaj in central Iran. Materials and Methods:Human stool samples (n=12 148) were randomly collected in Tehran and Karaj and examined for E. histolytica/E. dispar cysts with direct and formalin-ether methods. Eighty-seven (0.7%) cases were positive, of which 49 (62.8%) isolates were successfully cultured in Robinson's medium. A pair of oligonucleotide primers designed from sequence data for genomic DNA coding the 30-KD surface antigen of E. histolytica/E. dispar was used to amplify a 374 base-pair (bp) fragment. The electrophoretic pattern of the PCR product digested with Hinfl restriction enzyme was used for differentiation of the two species. Results: The restriction fragment length polymorphism (RFLP) pattern obtained from a standard E. histolytica isolate had two fragments (219 bp and 155 bp), but the standard isolate of E. dispar showed three fragments (155,152 and 67 bp Entamoeba histolytica is a cosmopolitan human protozoan parasite responsible for amoebic colitis and extraintestinal amoebiasis. Although 90% of infected individuals are asymptomatic, WHO estimates that every year more than 40 to 50 million cases of invasive amoebiasis occur in the world, resulting in up to 100 000 deaths. 1,2After malaria, amoebiasis is the second most fatal human protozoan parasitic diseases in the world. Many people infected with E. histolytica are asymptomatic and never develop clinical symptoms.3 What was earlier known as E. histolytica actually comprises two genetically distinct but morphologically identical species, one potentially pathogenic and the other non-pathogenic. 4 On the basis of biochemical, immunological and genetic data, a formal re-description of E. histolytica was published in 1993, separating E. histolytica (potential pathogenic) from the harmless commensal, E. dispar.5 Diagnosis and differentiation of the two species is important in therapy and also from an epidemiological point of view. Analysis of restriction fragment length polymorphism (RFLP) and direct sequencing of various genes amplified by polymerase chain reaction (PCR) has revealed 2.2% to 17% differences in the nucleotide sequences of E. histolytica and E. dispar. 6 These findings show that PCR and restriction enzyme digestion could be used as a powerful tool for distinguishing E. histolytica from E. dispar.In Iran, there are no accurate data on E. dispar. This study was carried out to determine the ratio of E. histolytica and E. dispar in a population in Tehran and Karaj in central Iran. Distribution and Differential Diagnosis of Entamoeba Histolytica from Entamoeba Dispar by the PCR-RFLP Method in Central Iran Annals of...

Detection and differentiation of Entamoeba histolytica and Entamoeba dispar by enzyme linked immuno sorbent assay

“…This espouse that amoebiasis infect male more than female, as indicated by [13,15,16] that males were more infected than females, which may be due to that males are more susceptible or they spend more time than females outdoor. But this result was not in agreement with those reported by [2,17] that both sexes have an equal rate of infection, or that the infection rate in women is higher than man [18] .…”

Sexually transmitted penile amoebiasis in Iran: a case series

“…However, the precise incidence or prevalence of invasive intestinal amoebiasis among inner-city residents of Tehran is unknown. In two recent epidemiological studies, prevalence of E histolytica varied between 6.1% and 7.9% when 49 and 102 intestinal amoebic isolates were tested, respectively 11 12. We hypothesised that unprotected insertive anal intercourse practiced by our patients facilitated transmission of colonic amoeba from their most recent sexual partners who were asymptomatic intestinal carries of E histolytica to the external male genitalia which, in turn, resulted in sexually transmitted PA.…”