Molecular differentiation of Entamoeba histolytica and Entamoeba dispar from Tunisian food handlers with amoeba infection initially diagnosed by microscopy.

Différenciation moléculaire des amibes Entamoeba histolytica et Entamoeba dispar identifiées chez les manipulateurs de denrées alimentaires en Tunisie

S. Ben Ayed (1) , Abdallah R Ben (1) , M. Mousli (2) , K. Aoun (1) , M. Thellier (3) , A. Bouratbine (1)

1 LR 05-SP 03 - Laboratoire des parasitoses émergentes, Institut Pasteur de Tunis
2 LVGM - Laboratoire d'Immunopathologie, Vaccinologie et Génétique Moléculaire
3 CHU Pitié-Salpêtrière [AP-HP]

The purpose of the study was to obtain more reliable epidemiological data concerning Entamoeba (E.) histolytica infection in Tunisian food handlers using established molecular tools able to differentiate E. histolytica from E. dispar. From 2002 to 2005, 4,266 fresh stools specimens received in the setting of the National program of food handlers' control were analysed by optical microscopy. Twelve (2.8 per thousand) were positive for the presence of four nuclei cysts identified as E. histolytica/E. dispar. Extraction of DNA from the 12 samples, followed by specific amplifications of E. histolytica and E. dispar SSU rDNA, showed that 11 samples (92%) were positive for E. dispar and negative for E. histolytica. Sequencing analysis of 8 PCR products permitted to verify the results obtained with conventional PCR. The remaining sample was negative by PCR amplifying E. histolytica DNA or E. dispar DNA specifically, although it did not show any inhibition. It probably contains protozoan cysts genetically distinct from these two species but morphological similar. Estimation of relative proportions between E. histolytica and E. dispar in cyst carriers showed that all explored individuals harboured the non pathogenic E. dispar strains. This result highlights the need of use in this population of complementary tests that allow specific diagnosis and obviate unnecessary chemotherapy.

Entre 2002 et 2005, 4 266 manipulateurs de denrées alimentaires de la région de Tunis ont bénéficié d’un examen parasitologique des selles dans le cadre du contrôle systématique. Douze (2,8 ‰) étaient porteurs de kystes d’Entamoeba histolytica/dispar. L’extraction d’ADN directement à partir des échantillons de selles positives, suivie respectivement d’une amplification génique de l’ADNr d ’E. histolytica et d’ E. dispar et d’un séquençage des produits d’amplification a permis d’identifier E. dispar chez 11 porteurs de kystes. Aucun manipulateur n’était porteur de l’espèce pathogène E. histolytica. Ces résultats mettent en exergue la nécessité d’examens complémentaires permettant l’identification des espèces E. histolytica et E. dispar et confirment la faible prévalence de l’amibiase dans le nord de la Tunisie.

Mots clés: Tunisia; Entamoeba histolytica; epidemiology; amoebiasis; Entamoeba dispar

Mots clés: Entamoeba histolytica; Entamoeba dispar; amibiase; épidémiologie; Tunisie

Domaines: Biologie structurale [q-bio.BM]

S. Ben Ayed, Abdallah R Ben, M. Mousli, K. Aoun, M. Thellier, et al.. Molecular differentiation of Entamoeba histolytica and Entamoeba dispar from Tunisian food handlers with amoeba infection initially diagnosed by microscopy.. Parasite, 2008, 15 (1), pp.65-68. ⟨10.1051/parasite/2008151065⟩. ⟨pasteur-00605380⟩