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Nested PCR reveals elevated over-diagnosis of E. histolytica in Barcelona, Venezuela
Hectorina Rodulfo1, Beatriz Ahmar, María E Rodríguez
1Laboratorio de Genética Molecular, Instituto de Investigaciones en Biomedicina y Ciencias Aplicadas "Dra. Susan Tai", Universidad de Oriente, Núcleo de Sucre, Cumaná, Venezuela.
Insights
Nested PCR revealed significant over-diagnosis of Entamoeba histolytica by microscopy in children. Molecular methods accurately identify Entamoeba species, improving diagnosis and treatment for parasitic infections.
Area of Science:
- Medical Parasitology
- Molecular Diagnostics
- Infectious Diseases
Background:
- Entamoeba histolytica and Entamoeba dispar are protozoan parasites causing amebiasis.
- Accurate differentiation between E. histolytica and E. dispar is crucial for appropriate patient management.
- Conventional microscopy often struggles to distinguish between these Entamoeba species.
Purpose of the Study:
- To determine the prevalence of Entamoeba histolytica and E. dispar in children using nested PCR.
- To evaluate the diagnostic accuracy of conventional microscopy compared to nested PCR for Entamoeba detection.
- To assess the clinical manifestations associated with Entamoeba infections in pediatric patients.
Main Methods:
- A total of 1,141 fecal samples from children aged 0-10 years were initially examined by conventional microscopy.
- 150 samples positive for E. histolytica by microscopy were further analyzed using nested PCR.
- Nested PCR was employed to differentiate between E. histolytica and E. dispar infections.
Main Results:
- Conventional microscopy diagnosed E. histolytica in 13.2% of cases, with 79.3% presumed to be solely this pathogen.
- Nested PCR confirmed Entamoeba spp. in only 28% of microscopy-positive samples, indicating substantial over-diagnosis.
- Prevalence rates by PCR were: 9.3% for E. histolytica, 4% for E. dispar, and 4.7% for mixed infections.
- Diarrhea, abdominal pain, and fever were common symptoms; bloody stools were associated with both E. histolytica and E. dispar.
Conclusions:
- Nested PCR significantly improves the accuracy of Entamoeba species identification compared to conventional microscopy.
- There is a high rate of over-diagnosis of Entamoeba histolytica when relying solely on microscopy.
- Molecular techniques are essential for precise epidemiological assessment and guiding appropriate treatment strategies for amebiasis.
Abstract:
The aim of this study was to identify the presence of Entamoeba histolytica and E. dispar by nested PCR in children attending the "Dr. Luis Razetti" Hospital, Barcelona, Anzoátegui State. Of the 1,141 fecal samples coproparasitologically evaluated by conventional microscopy, 150 were diagnosed positive for E. histolytica in 0-10 year-old-children, of both sexes. The signs, symptoms and a full coproparasitological report were obtained from all of these and nested PCR was performed to identify E. histolytica and E. dispar. The conventional microscopy results showed a diagnostic frequency of E. histolytica in 13.2% of the cases, of which 79.3% were positive only for this pathogen. However, nested PCR showed that of these, only 28% (42/150) were actually infected by Entamoeba spp., revealing a high over-diagnosis of E. histolytica. We also identified 9.3% E. histolytica, 4% E. dispar and 4.7% mixed infections. Diarrhea was the most common symptom, followed by abdominal pain and fever. Bloody stools were statistically associated with E. histolytica, but were also found for E. dispar infections. This study demonstrates that molecular techniques complementary to conventional methods enable the correct identification of Entamoeba spp., thus contributing to an improved epidemiological assessment of these parasites and implementation of the appropriate treatment.
