Association between amoebiasis and sexually transmitted infections in Japan

Abstract

Background: Amoebiasis is an infectious disease caused by Entamoeba histolytica and presents mainly colitis and liver abscess as a food and water-borne infection or sexually transmitted infections (STIs). Amoebiasis is known to occur more frequently among the persons who are living with HIV, especially men who have sex with men in developed countries. However, the association between amoebiasis and STIs is not clear. Methods & Materials: Cases of amoebiasis treated at our hospital between 2005 and 2019 were retrospectively examined based on medical records. Amoebic colitis (AC) patients were determined as cases who were detected Entamoeba spp. by microscopic examination of stool or pathological examination of the mucosa of the large intestine. Amoebic liver abscess (ALA) patients were determined as cases who were detected Entamoeba spp. from pus or whose amoebic antibody was positive. Results: There were 267 cases of amoebiasis, including 228 AC cases (85%) and 39 ALA cases (15%). Age (median [IQR]) was 46 [38–56] years, 91% was male and 98% was Japanese. The history of hepatitis B, hepatitis C, syphilis and HIV were positive in 46%, 9%, 39% and 37%. Sixty-six percent had history of either STIs, and STI-related amoebiasis were significantly more ALA (risk ratio [95% CI]: 2.6 [1.1–6.5]). Individually, hepatitis B, HIV and syphilis related amoebiasis were significantly more ALA (6.0 [2.6–14.1], 3.7 [1.8–7.8], 2.1 [1.0–4.2]). Of 75 HIV related amoebiasis, 32% were under antiretroviral therapy (ART), median CD4 count was 275 [96–432]/μL and median HIV load was 35,000 [50–98,000] copies/mL. Presence of ART, CD4 count and HIV load were not significantly related to ALA. Conclusion: Cases of amoebiasis associated with hepatitis B, HIV and syphilis had progressed significantly more frequently to ALA. Among HIV related amoebiasis, level of cellular immunity and presence of ART were not related to progression to ALA. So, we consider that sexually transmitted amoebiasis may be related to progression to ALA.