Comparison of stool antigen detection kits to PCR for diagnosis of amebiasis

The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of Entamoeba histolytica infections by using fecal specimens submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, and the Institute of Medical and Veterinary Science, Adelaide, Australia. A total of 279 stool samples containing the E complex (E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii) were included in this study. The stool specimens were tested by using two commercially produced enzyme immunoassays (the Entamoeba CELISA PATH and TechLab E. histolytica II kits) to detect antigens of E. histolytica. DNA was extracted from all of the samples with a Qiagen DNA stool mini kit (Qiagen, Hilden, Germany), and a PCR targeting the small-subunit ribosomal DNA was performed on all of the samples. When PCR was used as a reference standard, the CELISA PATH kit showed 28% sensitivity and 100% specificity. The TechLab ELISA (enzyme-linked immunosorbent assay) kit did not prove to be useful in detecting E. histolytica, as it failed to identify any of the E. histolytica samples which were positive by PCR. With the TechLab kit, cross-reactivity was observed for three specimens, one of which was positive for both E. dispar and E. moshkovskii while the other two samples contained E. moshkovskii. Quantitative assessment of the PCR and ELISA results obtained showed that the ELISA kits were 1,000 to 10,000 times less sensitive, and our results show that the CELISA PATH kit and the TechLab ELISA are not useful for the detection of E. histolytica in stool samples from patients in geographical regions where this parasite is not endemic.

Diagnosis of Entamoeba histolytica in symptomatic children, Jeddah City, Saudi Arabia

Amebiasis is one of the most common parasitic infections worldwide. Entamoeba histolytica and Entamoeba dispar are two morphologically indistinguishable human protozoa parasites that are genetically distinct species. Differential diagnosis of E. histolytica (pathogenic) and E. dispar (non-pathogenic) is essential both for treatment decision and public health knowledge. Stool samples from 500 randomly selected children complaining of gastroenteritis were examined microscopically by direct wet smear and subjected to detection of E. histolytica antigen by ELISA using TechLab E. histolytica II test. E. histolytical E. dispar were also identified at molecular level by targeting the 166 bp, and 752 bp sequences of the 18Sr RNA gene of E. histolytica and E. dispar respectively using polymerase chain reaction technique (PCR). The overall prevalence of E. histolytica/dispar by microscopic examination was 30/500 (6%). E. histolytica was positive in 161500 (3.2%) by antigen detection ELISA technique, whereas 10 samples were not detected microscopically. PCR was able to confirm the presence of E. histolytica in 13/16 cases whereas the 3 samples recorded negative were positive by ELISA; even so there was a good agreement k = 0.86 between the two techniques. In conclusion, stool antigen detection test by ELISA is recommended over PCR in detecting and confirming E. histolytica amoebic enteritis.

Long term formalin preserved stool specimens for detection of intestinal parasites from school aged children in Tripoli, Libya

A total of 949 single stool samples were collected from school aged children (5-14 years old) in the city of Tripoli. The samples were preserved in 10% formalin and examined by routine microscopy using normal saline and Lugol's iodine preparations as well as the formol ethyl concentration method after a storage period of twelve months at room temperature. Of 949 samples examined 4.5% were positive. Giardia lamblia and Entamoeba coli were the only protozoan parasites identified with an infection rate of 3.2% & 1.3% respecttively. No helminthes were detected in any of the samples. About 14% of the children had intestinal yeast infection Candida albicans in their stool of which 0.63% was infected with intestinal parasites. No distortion or alteration of morphology was observed particularly in G. lamblia. Preservation in 10% formalin is a very productive means for the accurate identification of protozoan parasites.

Diagnosis of intestinal amoebiasis by using nested polymerase chain reaction-restriction fragment length polymorphism assay

BACKGROUND

Microscopy is unreliable to distinguish the pathogenic Entamoeba histolytica from the nonpathogenic Entamoeba dispar or Entamoeba moshkovskii in stool specimens.

METHODS

Nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was carried out to detect E. histolytica, E. dispar, and E. moshkovskii DNA in stool samples of 202 patients positive for E. histolytica, E. dispar, or E. moshkovskii by microscopy or culture and in 35 controls. The TechLab E. histolytica II enzyme-linked immunosorbent assay (ELISA) was performed to detect Gal/GalNAc lectin in 45 stool samples positive for E. histolytica, E. dispar, or E. moshkovskii by microscopy or culture. Rapid-indirect hemagglutination assay (IHA) was performed to detect serum antiamoebic antibodies in the 85 patients positive for E. histolytica, E. dispar, or E. moshkovskii in their stool specimens and in the 35 controls.

RESULTS

Nested PCR-RFLP was positive in 175 of 202 (86.6%) patient stool samples and was negative in all 35 negative control stool samples. ELISA was positive in 29 of 45 (64.4%) patient stool samples. The IHA test was positive in 19 of 85 (22.4%) patient serum samples and in one (2.8%) of the 35 control serum samples. Nested PCR-RFLP detected E. histolytica DNA in stool specimens of 12 (63.2%) of 19 seropositive patients, and in 31 (47%) of 66 seronegative patients. TechLab E. histolytica II ELISA detected E. histolytica antigen in stool specimens of six (54.5%) of 11 seropositive patients, and in 23 (67.6%) of 34 seronegative patients.

CONCLUSIONS

Nested PCR-RFLP was useful for the specific detection of E. histolytica, E. dispar, and E. moshkovskii in stool samples.

Prevalence of intestinal parasitic infestation in HIV/AIDS patients with diarrhea in Madurai City, South India

The prevalence and pattern of parasitic infestation among 80 HIV/AIDS patients with diarrhea in Madurai, south India, was studied by microscopy. Eighty HIV-negative patients were used as controls. Intestinal parasites were detected in 31 HIV/AIDS patients (38.7%) and in 14 (17.5%) HIV-negative patients, a difference that was statistically significant (P < 0.05). In HIV/AIDS patients with diarrhea, protozoa accounted for the majority of diarrhea cases (Entamoeba spp. 37.5%, Cryptosporidium parvum 28.7%). It is therefore suggested that enteric infections are more common in HIV-infected patients than in HIV-negative persons in south India, and this may be due to differences in immunological profile, susceptibility as well as factors related to sanitation and the environment.

Laboratory diagnostic techniques for Entamoeba species

The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

An Entamoeba sp. strain isolated from rhesus monkey is virulent but genetically different from Entamoeba histolytica☆

An Entamoeba sp. strain, P19-061405, was isolated from a rhesus monkey in Nepal and characterized genetically. The strain was initially identified as Entamoeba histolytica using PCR amplification of peroxiredoxin genes. However, sequence analysis of the 18S rRNA gene showed a 0.8% difference when compared to the reference E. histolytica HM-1:IMSS human strain. Differences were also observed in the 5.8S rRNA gene and the internal transcribed spacer (ITS) regions 1 and 2, and analysis of the serine-rich protein gene from the monkey strain showed unique codon usages compared to E. histolytica isolated from humans. The amino acid sequences of two hexokinases and two glucose phosphate isomerases also differed from those of E. histolytica. Isoenzyme analyses of these enzymes in the monkey strain showed different electrophoretic mobility patterns compared with E. histolytica isolates. Analysis of peroxiredoxin genes indicated the presence of at least seven different types of protein, none of which were identical to proteins in E. histolytica. When the trophozoites from the monkey strain were inoculated into the livers of hamsters, formation of amebic abscesses was observed 7 days after the injection. These results demonstrate that the strain is genetically different from E. histolytica and is virulent. Revival of the name Entamoeba nuttalli is proposed for the organism.

Comparison of multiplex-PCR and antigen detection for differential diagnosis of Entamoeba histolytica

Amebiasis is an infection caused by Entamoeba histolytica. However, differentiation between E. histolytica and Entamoeba dispar, which are morphologically identical species, is essential for treatment decision, precaution of the invasive disease and public health. The purpose of the present study was to evaluate a Multiplex -PCR for detection and differentiation of E. histolytica from E. dispar from fresh stool samples in comparison with the coproantigen commercial ELISA. Microscopic examination of stools using the Coprotest method, detection of stool antigen by enzyme-linked immunosorbent assay kit and a home made Multiplex-PCR, were used for the diagnosis of amoebiasis infection. Analysis of the 127 stools samples by microscopy examination demonstrated that only 27 (21%) samples were positive for E. histolytica/E. dispar complex. Among these stool samples, 11 were positive by Multiplex-PCR, with nine presenting the diagnostic fragment characteristic of E. dispar (96 bp) and two presenting diagnostic fragment of E. histolytica (132 bp). Among negative samples detected by microscopic examination, three positive samples for E. dispar and one positive for E. histolytica by Multiplex-PCR was observed. This denotes a low sensibility of microscopic examination when a single stool sample is analyzed. Assay for detection of E. histolytica antigen was concordant with multiplex-PCR in relation to E. histolytica. Statistical analysis comparing the sensibility tests was not done because of the low number of E. histolytica cases. The results demonstrate the importance of the specific techniques use for the differentiation between E. histolytica and E. dispar.

[Occurrence of Entamoeba histolytica/Entamoeba dispar in ambulatory patients of Recife, PE]

The objective this study was to determine the occurrence of the species Entamoeba histolytica/Entamoeba díspar in clinical samples of ambulatory patients in Pernambuco. A specific assay for Entamoeba histolytica was used in this study, which identified no positive fecal samples among the 213 patients. These results confirm that E. dispar is the dominant species in Pernambuco State.

Prevalence of intestinal parasites among primary schoolchildren in Derna District, Libya

The prevalence of intestinal parasites and some hygienic factors was evaluated in primary schoolchildren in Derna District. A total of 1039 stool specimens were examined by direct smear and formaline-ether concentration methods. The results showed that 31% of the children were infected with at least one or two parasites. These parasites were Giardia lamblia (12.7%), Blastocystis hominis (6.7%), Entamoeba histolytica/ Entamoeba dispar (6.6%), Entamoeba coli (3.2%), E. hartmanni (1.0%), Enterobius vermicularis (0.6%), Ascaris lumbricoides (0.1%) and Hymenolepis nana (0.1%). A significant difference was between infection rate and parent's education (P = 0.000), socio-economic status of the family (P = 0.000), family size and number of rooms in houses (P = 0.000). Also, there was a significant differences between infection rate and source of water for human consumption (P = 0.05).

Detection and differentiation of Entamoeba histolytica and Entamoeba dispar isolates in clinical samples by PCR

A total of 140 out of 180 outpatients attended MISR University for Science and Technology Hospital complained of abdominal pain, diarrhoea and/or dysentery. Stool examination showed 47 (33.6%) had Entamoeba sp., 36 (25.7%) had cysts and 11 (7.9%) had trophozoites. Of 40 asymptomatic ones, 4 (10%) had cysts. A total of 51 positive stool samples for Entamoeba sp. (40 cysts & 11 trophozoites) were tested by Ne-sted Polymerase Chain Reaction (N-PCR) and Restriction Enzyme Digestion (RED) to clarify true E. histolytica from E. dispar. The results showed that 9/51 (17.6%) had E. dispar, while 31 (60.8%) had E. histolytica and 11 (21.6%) had dual infection with both E. histolytica and E. dispar. All E. histolytica PCR proved cases were from the symptomatic group, 11 had trophozoites and 34 had cysts. Thus, the result showed the potential use of molecular tools in detection of E. histolytica and E. dispar, and is a promising tool for epidemiology, particularly to differentiate pathogenic and non pathogenic Entamoeba sp.

Anterior necrotizing scleritis after strabismus surgery in a child

Anterior necrotizing scleritis is a rare but potentially devastating complication of ocular surgery that most often occurs after cataract surgery in elderly patients who may have an underlying systemic autoimmune condition(1) or, less likely, an infectious cause.(2) We describe the management and outcome of a case of bilateral anterior necrotizing scleritis after postoperative infection in a 19-month-old girl who had recently undergone strabismus surgery.

[Confirmation by PCR of the existence in Tunisia of Entamoeba histolytica and Entamoeba dispar]

AIM

Amibias are illness in Tunisia diagnosed until now on the sole basis of the morphological aspects of the parasite. Our aim is to report the first Tunisian results concerning the molecular identification of E. histolytica/E. dispar,

METHODS

25 stools presenting cysts and/or vegetative shapes of E. histolytica/E. dispar were gathered at the "Laboratoire de Parasitologie Hôpital La Rabta Tunis" between 2001and 2004 for PCR. The stools came from 24 subjects, one of them having two samples: 9 Tunisian patients, 5 adressed to the hospital services for abdominal pains or diarrheas and 4 adressed for a systemic tracking (food manipulation), and 15 foreign students for which a tracking is done each fall.

RESULTS

The identification showed thus for the Tunisian patients the presence of : E. histolytica alone for a patient (food manipulator) 11%. E. histolytica associated to E. dispar for two patients 22%. E. dispar alone for six patients 67%. Nearly similar results has been obtained for foreign student's samples: E. histolytica alone in one case (7%), E. histolytica associated to E. dispar in four cases (26%) and E. dispar alone in 10 cases (67%).

CONCLUSION

These results show therefore the existence in Tunisia the two species E. histolytica and E. dispar for symptomatic or non symptomatic patients. The distinction between the two species is very important on the therapeutic level as well as the epidemiologic and public health level.

PCR detection of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from Sydney, Australia

This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.

[Pathogenic Entamoeba histolytica--a rare incidence in persons microscopically positive for cysts in faeces]

BACKGROUND

In the Czech Republic, 40 to 50 cases of Entamoeba histolytica/dispar infections are reported annually to the National Reference Laboratory for diagnostics of intestinal parasitoses. However, the actual number of patients with Entamoeba histolytica infection is unknown as diagnosis relies on cyst detection in faecal samples by microscopy, the method which cannot differentiate between pathogenic E. histolytica and nonpathogenic E. dispar. The aim of this study was (1) to evaluate the proportions between E.histolytica and E. dispar in patients, mainly travellers, using multiplex nested PCR technique, (2) to evaluate specificity of the technique for detection of these species.

METHODS AND RESULTS

Faecal samples from 68 patients microscopically positive for cysts of E. histolytica/dispar were tested by PCR. Of these, 65 persons (95.6%) were positive for E. dispar, whereas only 3 patients (4.4%) were positive for E. histolytica.

CONCLUSIONS

This study shows that the number of patients infected with pathogenic E. histolytica is very low in the Czech Republic and points to the necessity of differentiation of Entamoeba species for physician's decision in treatment of E. histolvtica- or E.dispar-infected persons.

[Screening of intestinal parasites of children in special day nurseries in the city of Rize]

In this study, the carriage of intestinal parasites was investigated in a total of 73 children (35 girls, 38 boys) in the 1-6 age-group in two special day nurseries in the city of Rize. Stool samples and cellophane tape preparations were obtained from children three times a month. Parasite cysts or eggs were found in total of 15.0% of the stool samples or cellophane tape preparations from children. It has been determined that 8.5% of the girls and 21.0% of the boys were parasite porters, and that all of these were asymptomatic carriers. Giardia intestinalis, Entamoeba coli + Iodamoeba bütschlii, Taenia spp. and Enterobius vermicularis were detected at rates of 11.0%, 1.3%, 1.3% and 1.3%, respectively.

[Intestinal protozoa in children of child day care centers and orphanages of Moscow]

On the basis of an analysis of the contamination with intestinal protozoa in 373 Moscow children and comparison of the data of a randomized protozoological study of matched groups of 543 children from three towns of the Russian Federation in the past 15 years, the authors revealed profound changes in the pattern of intestinal parasitocenosis in the examinees: preponderance of B. hominis recently reclassified as a protozoan in all groups of examinees; a reduction in the detectable protozoan types up to a single type both among parasitic amoebas (E. coli) and flagellates (L. intestinalis). The incidence of giardiasis among the children's collective bodies averaged 3.5% and that in the kindergartens was 0.5%.

Differentiation of Entamoeba histolytica and Entamoeba dispar by PCR: a preliminary study in Izmir, Turkey

The causative agent of amoebiasis is currently attributed to two distinct species (E. histolytica and E. dispar). The aim of this study was to differentiate these species by PCR in stool samples. Isolated genomic DNA was amplified by PCR and band products of 101 bp (E. dispar) were obtained. All seven stool samples were found to be E. dispar, not E. histolytica. Our results demonstrated the significance of E. histolytica/dispar differentiation in the diagnosis of amoebiasis. This study is preliminary to our current research project entitled "Investigation of the prevalence of amoebiasis and Entamoeba species in Izmir and its hinterland".

[Occurrence of human intestinal parasites in selected populations of Cracow region in the years 2000-2006 on the basis of parasitological stool examinations performed in the Laboratory of Parasitology of the District Sanitary-Epidemiological Center]

BACKGROUND

Infections with intestinal parasites are the most frequent parasitic diseases in all human populations. According to available epidemiological data enterobiosis, giardiosis and ascariosis are the most prevalent in Poland. The aim of this study was to evaluate the prevalence of human intestinal parasites in three selected populations in Cracow between 2000-2006.

MATERIAL AND METHODS

As many as 5383 stool samples were tested with the use of coproscopic methods and ELISA for the presence of Giardia intestinalis coproantigen.

RESULTS

In 283 stool samples different species of intestinal parasites were detected. The prevalence of human intestinal parasites was minimal in 2002, with the ratio of 3.30%, while the maximal prevalence was noted in 2005 (8.86%). The mean prevalence of intestinal parasites in 2000-2006 was 5.26%. In this period of time the most prevalent intestinal parasite among children and adults was Enterobius vermicularis (2.35% and 1.84% respectively), and in the population of citizens returning from the tropics were Entamoeba coli (6.98%). Besides, a gradual trend of decrease in the number of patients referred directly to our laboratory for parasitic examination of stool samples was noted over the last years.

Intestinal protozoan infections and echinococcosis in the inhabitants of Dornod and Selenge, Mongolia (2003)

The status of intestinal parasitic infections and seroprevalence of cystic echinococcosis in the inhabitants in Dornod and Selenge, Mongolia, was observed with stool and serum samples from 165 and 683 residents from August 9 to August 15, 2003. A total of 10 inhabitants (6.1%) were found to be infected with protozoan cysts or oocysts by stool examinations; 7, 1 and 2 cases with Entamoeba coli, Giardia lamblia and Cryptosporidium parvum, respectively. A total of 62 people (9.1%) revealed significantly high levels of specific antibodies against Echinococcus granulosus by enzyme-linked immunosorbent assay (ELISA). The surveyed areas are rural areas and the sanitized tab water is not available. There is a possibility of endemic transmission of water-borne protozoan diseases in these areas. The clinical echinococcosis is needed to be searched from the seropositive inhabitants.

Differential detection of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii by a single-round PCR assay

A single-round PCR assay was developed for detection and differential diagnosis of the three Entamoeba species found in humans, Entamoeba moshkovskii, Entamoeba histolytica, and Entamoeba dispar, that are morphologically identical as both cysts and trophozoites. A conserved forward primer was derived from the middle of the small-subunit rRNA gene, and reverse primers were designed from signature sequences specific to each of these three Entamoeba species. PCR generates a 166-bp product with E. histolytica DNA, a 752-bp product with E. dispar DNA, and a 580-bp product with E. moshkovskii DNA. Thirty clinical specimens were examined, and the species present were successfully detected and differentiated using this assay. It was possible to detect as little as 10 pg of E. moshkovskii and E. histolytica DNA, while for E. dispar the sensitivity was about 20 pg of DNA. Testing with DNA from different pathogens, including bacteria and other protozoa, confirmed the high specificity of the assay. We propose the use of this PCR assay as an accurate, rapid, and effective diagnostic method for the detection and discrimination of these three morphologically indistinguishable Entamoeba species in both routine diagnosis of amoebiasis and epidemiological surveys.

Differentiation of Entamoeba histolytica from Entamoeba dispar by PCR-coupled nonisotopic SSCP analysis

Entamoeba histolytica is a pathogenic protozoan parasite, which causes amoebic colitis, dysentery and liver abscesses in humans. Since the cyst and small trophozoite stages of this parasite are indistinguishable by light microscopy from Entamoeba dispar (which is nonpathogenic), specific diagnosis is compromised. To overcome this limitation, a PCR-coupled SSCP approach, utilising a sequence difference of 4.6% in a short region ( approximately 173-174 bp) of the small subunit of nuclear ribosomal DNA, was evaluated for the differentiation of the two species of Entamoeba. Including a range of well-defined control DNA samples (n = 67) to evaluate the specificity of the PCR, 45 DNA samples representing E. histolytica and E. dispar from human faecal samples were tested by SSCP, and unequivocal delineation between the species was achieved. This SSCP approach should provide a practical tool for the specific diagnosis of E. histolytica in humans and for investigating its epidemiology.

Overdiagnosis of Entamoeba histolytica and Entamoeba dispar in Nicaragua: a microscopic, triage parasite panel and PCR study

BACKGROUND

Based on stool microscopy, an E. histolytica/E. dispar prevalence of 18.6% was found in León, Nicaragua about 10 years ago. Since then, new non-microscopic methods have been developed to discriminate between pathogenic E. histolytica and nonpathogenic E. dispar. The main objectives of the present study were to evaluate the true prevalence of E. histolytica among individuals with diarrhea and to assess the diagnostic procedures carried out at the health center level.

METHODS

A descriptive study was carried out on patients with diarrhea. Parasite detection was performed by conventional microscopy on native preparations or concentrated and stained specimens, Triage Parasite Panel and by PCR for both E. histolytica and E. dispar.

RESULTS

In 134 individuals with diarrhea, the prevalence of intestinal parasites was 69% as detected by direct stool examination. E. histolytica/E. dispar was found in eight (6%) of the samples, but the health centers reported 24%. In the Triage Parasite Panel only one case of E. histolytica/E. dispar was found. Analysis by PCR showed E. dispar in ten (7.5%) and E. histolytica in two cases (1.5%). The detection of intestinal coccidia and Dientamoeba fragilis required additional staining methods.

CONCLUSIONS

PCR results showed that E. histolytica is a rare finding in patients with diarrhea. At the health centers, E. histolytica, E. histolytica/E. dispar were clearly overdiagnosed, with the consequence of overtreatment.

Comparison of a stool antigen detection kit and PCR for diagnosis of Entamoeba histolytica and Entamoeba dispar infections in asymptomatic cyst passers in Iran

The present study was conducted to compare stool antigen detection with PCR for the diagnosis of Entamoeba sp. infection in asymptomatic cyst passers from Iran. Entamoeba dispar and, in one case, E. moshkovskii were the Entamoeba spp. found in the amebic cyst passers. There was a 100% correlation between the results from the TechLab E. histolytica II stool antigen kit and those from nested PCR. We concluded that E. dispar is much more common in asymptomatic cyst passers in Iran and that antigen detection and PCR are comparable diagnostic modalities.