Absence of detectable local antibody in genitourinary tract secretions of male contacts of women infected with Trichomonas vaginalis.

Samples of semen and urine were obtained from 37 male contacts of women with proved Trichomonas vaginalis infection; on culture, eight (22%) of the men were shown to harbour the parasite. However, significant amounts of antitrichomonal antibody were found in only two of these samples, and the amounts present were very small. A further 10 samples were tested but none was found to contain antibody. The asymptomatic nature and low parasite numbers commonly described in infections in men is thus unlikely to be due to a vigorous local immune response.