IntroductionThe increase in the number of reports of anal intraepithelial neoplasia (AIN), carcinoma-in-situ and squamous cell carcinoma in association with anal

In a study of bowel parasites in 128 Australian homosexual men attending a sexually transmitted diseases (STD) clinic, Entamoeba histolytica was detected in 37%, Giardia intestinalis in 3% and at least one protozoan in 81% of the group. There was no evidence of pathogenicity of E. histolytica, nor was there any association between the detection of E. histolytica and sexual practices, gastrointestinal symptoms, proctitis, human immunodeficiency virus antibody result or T-cell subset values. However it was noted that those subjects with an elevated IgM greater than 4 g/l were more likely to harbour E. histolytica trophozoites than those with a level below 4 g/l (OR 6.54, 95% CI 1.3-32.8). Travel to South-East Asia, India, China, Africa, South America or the Pacific islands in the previous 3 years emerged also as an independent factor (OR 2.70, 95% CI 1.12-6.53) associated with detection of E. histolytica.