Abstract
We found eleven human immunodeficiency virus (HIV)-positive practicing homosexual men with amebic infection in Japan. Clinical symptoms compatoble with invasive amebiasis were demonstrated in ten of them. Actively motile trophozoites of ameba with ingested erythrocytes, identified as Entamoeba histolytica, were detected in the stool or liver abscess pus from five of the symptomatic cases, whereas in another symptomatic case ameba, also identified as E. histolytica, was histologically found from a biopsied specimen of the colon. Anti-E. histolytica antibody was not detected in one of thse six cases irrespective of the serologic methods employed, and gel diffusion precipitin test (GDP) was negative in another one of them. Among the remaining five individuals, two were negative by GDP, and one of the two also by enzyme-linked immunosorbent assay; however, these 2 GDP-negative cases were judged positive by polymerase chain reaction using E. histolytica-specific primers. These findings suggest that serologic tests for invasive amebiasis, in particular GDP, sometimes show misleading reactions in the case concurrently infected with HIV and E. histolytica. In contrast to western contries, invasive amebiasis by E. histolytica appears to be associated with acquired immunodeficiency syndrome (AIDS) in Japan.
Key words: Entamoeba histolytica; Protozoa, parasitic; sexually transmitted amebiasis; acquired immunodeficiency syndrome (AIDS); serology.