A sample of returned travelers who sought health care from 2007 through 2011 at any of 53 international GeoSentinel-associated clinics showed that most people diagnosed with E. histolytica had traveled for tourism to India, Indonesia, Mexico, or Thailand, as opposed to visiting with friends and relatives or traveling for business. Nevertheless, cases of amebiasis are not restricted to these countries and are distributed worldwide, particularly in the tropics, most commonly in areas of poor sanitation.
Molecular methods using the polymerase chain reaction amplify E. histolytica genes from extracted faecal DNA. Sensitivity and specificity are high (80%–100% and 100%, respectively). The advantage of molecular detection is that it is extremely sensitive (able to detect < 1 parasite) and reliably able to differentiate non-pathogenic Entamoeba species from E. histolytica. Drawbacks of this method are the high level of expertise required and the cost. For symptomatic intestinal infection and extraintestinal disease, treatment with metronidazole or tinidazole should be followed by treatment with iodoquinol or paromomycin.
Most patients have a gradual illness onset days or weeks after infection. Symptoms include cramps, watery or bloody diarrhea, and weight loss and may last several weeks. Occasionally, the parasite may spread to other organs (extraintestinal amebiasis), most commonly the liver. Amebic liver abscesses may be asymptomatic.