The relation between size and pathogenicity of Trichomonas vaginalis.

Abstract

SummaryVaginal trichomoniasis was found in 7.6 per cent of women admitted to medical and surgical wards of a general hospital. Three‐quarters of the infected patients had small trichomonads (average diameter less than 16μ), and half of these reported vaginal discharge and sometimes irritation; most of them had marked inflammatory changes in desquamated vaginal squamous cells. Patients infected with large trichomonads (16μ or more) were asymptomatic. During culture in vitro of small trichomonad strains for up to 30 days, the organisms present tended to become progressively larger and giant forms appeared. With large trichomonad strains there was some decrease in size during the first three days, but thereafter changes in the cultures resembled those seen in cultures derived from small strains. After prolonged culture, size and morphology of organisms derived from small and large strains became identical. Patients with carcinoma in situ of the cervix and vaginal trichomoniasis tended to harbour small trichomonads.