Seroprevalence ofEntamoeba histolyticaat a voluntary counselling and testing centre in Tokyo: a cross-sectional study

Abstract

BackgroundAmebiasis, which is caused byEntamoeba histolytica, is a re-emerging public health issue owing to sexually transmitted infection (STI) in Japan. However, epidemiological data are quite limited.MethodsTo reveal the relative prevalence of sexually transmittedE. histolyticainfection to other STIs, we conducted a cross-sectional study at a voluntary counselling and testing (VCT) centre in Tokyo. Seroprevalence ofE. histolyticawas assessed according to positivity with an ELISA forE. histolytica-specific IgG in serum samples collected from anonymous VCT clients.ResultsAmong 2083 samples, seropositive rate forE. histolyticawas 2.64%, which was higher than that for HIV-1 (0.34%, p<0.001) and comparable to that for syphilis (rapid plasma reagin (RPR) 2.11%, p=0.31). Positivity forChlamydia trachomatisin urine by transcription-mediated amplification (TMA) was 4.59%. Seropositivity forE. histolyticawas high among RPR/Treponema pallidumhemagglutination (TPHA)-positive individuals and it was not different between clients with and without other STIs. Both seropositivity ofE. histolyticaand RPR were high among male clients. The seropositive rate for anti-E. histolyticaantibody was positively correlated with age. TMA positivity for urineC. trachomatiswas high among female clients and negatively correlated with age. Regression analysis identified that male sex, older age and TPHA-positive results are independent risk factors ofE. histolyticaseropositivity.ConclusionsSeroprevalence ofE. histolyticawas 7.9 times higher than that of HIV-1 at a VCT centre in Tokyo, with a tendency to be higher among people at risk for syphilis infection. There is a need for education and specific interventions against this parasite, as a potentially re-emerging pathogen.