Entamoeba Histolytica/Entamoeba Dispar Infections in Human Immunodeficiency Virus-Infected Patients in the United States [Lowther SA, et al. CID 2000; 30: 955]: This is a report from the CDC Adult and Adolescent Spectrum of HIV Disease Project concerning the frequency of E. histolytica or E. dispar by stool microscopy in 34,063 HIV-infected patients followed for 82,518 person-years. The incidence was 13.5 cases per 10,000 patient-years and was most common in gay men.
Comment: This is the largest study of Entamoeba infections in a developed country and shows a low prevalence of 3.3%. Unfortunately, the laboratory diagnosis was largely limited to stool microscopy, which does not distinguish E. histolytica and E. dispar. The distinction is critical because E. histolytica is responsible for enteric disease and liver disease whereas E. dispar is nonpathogenic and does not require therapy. The distinction is made by serologic testing or by stool ELISA. In this report, there were only two cases clearly ascribed to E. histolytica, but 101 were treated. In an accompanying editorial by Sharon Reed [CID 2000; 30: 959] the author points out the imperfections in studies to distinguish these two Entamoeba species using serology or antigen detection assays and that new and better tests are needed. posted 8/11/2000