Epidemiological, clinical, and diagnostic data on intestinal infections with Entamoeba histolytica and Entamoeba dispar among returning travelers

Abstract

Among travelers returning from the tropics, Entamoeba spp. are among the most frequently detected intestinal parasites, mainly the presumable apathogenic E. dispar and the pathogenic E. histolytica. Among 5,378 travelers seeking diagnosis and treatment for intestinal infections at the travel clinic of the University of Munich between 2005 and 2009, 103 laboratory-confirmed amebiasis cases were detected. The study compares the results of various diagnostic tests among these patients, analyzes data on co-infections and clinical symptoms, and determines the risk for acquiring amebiasis. Initial screening tests (stool microscopy, coproantigen enzyme-linked immunosorbent assay [ELISA]) were positive in 82.5 and 93.9%, respectively. Fecal samples from patients with positive screening test results were subjected to polymerase chain reaction (PCR), which detected E. histolytica in 9.7% and E. dispar in 88.3% of the cases. The majority of E. histolytica cases and more than half of the E. dispar cases had intestinal symptoms typical for amebiasis. In 53.4% of the cases, intestinal co-infections were found, mostly Blastocystis hominis (39.8%), Giardia lamblia (10.7%), Campylobacter spp. (4.9%), and Salmonella typhi (2.9%). The risk for travelers to be infected with E. histolytica or E. dispar was highest for destinations in West Africa, East Africa, and South and South-East Asia. Stool microscopy and coproantigen ELISA are appropriate screening tests for intestinal Entamoeba infections among travelers, but intestinal co-infections are common. PCR is highly recommended as the diagnostic method of choice for the differentiation of Entamoeba spp. The presumable apathogenic E. dispar seems to provoke intestinal symptoms.