Studies on the lethal effect of ultraviolet light onTrichomonas vaginalis

Abstract

Following cultivation in Asami medium, centrifugation and resuspension in saline or in water from a medicinal spring, Trichomonas vaginalis trophozoites were exposed to well-defined doses of ultraviolet (UV) light (254 nm). We used 24- and 48-h-old trichomonads at concentrations of 1 x 10(5) and 5 x 10(4) trophozoites/ml in a total volume of 20 ml for these studies. The apparatus for UV irradiation was especially constructed for batch experiments. After irradiation at doses ranging from 80 to 160 mJ/cm2, the mobility of the parasites was reduced and morphological alterations appeared: rounding of the cells, vacuolization of the cytoplasm and even cytolysis. A dose of 401.7 mJ/cm2 killed 99.8% of the 48-h-old trichomonads when irradiation occurred in saline at a cell density of 1 x 10(5) trichomonads/ml and 98.9% when irradiation was done at a cell density of 5 x 10(4) trichomonads/ml. A dose of 362.1 mJ/cm2 killed only the more sensitive 24-h-old trichomonads. In mineral water, 241 mJ/cm2 was sufficient to kill up to 99.5% of the 48-h-old trichomonads. When 48-h-old trichomonads that had been exposed to a radiation dose of 160-240 mJ/cm2 were subcultured, they lost their ability to propagate. At a dose of 80 mJ/cm2, both the trichomonads that had been harvested during the log phase and the 48-h-old organisms suspended in mineral water lost their ability to propagate on subculture. These results indicate that 24-h-old trichomonads were more sensitive than 48-h-old organisms. Furthermore, the experiments demonstrated that a higher dose of UV radiation must be applied to T. vaginalis trophozoites than to the more sensitive bacterial strain Escherichia coli ATCC 11229 so as to achieve comparable killing results.

Giardiasis: A Histologic Analysis of 567 Cases

“…'I'his is in keeping with results published by Seitz and his colleagues, who lound that 4% of all stool specimens stiliinittetl were positive for Giariliu cysts (12). 'I'his is in keeping with results published by Seitz and his colleagues, who lound that 4% of all stool specimens stiliinittetl were positive for Giariliu cysts (12).…”