Virulence differences in mice of type A and B Histoplasma capsulatum yeasts grown in continuous light and total darkness.

Type B yeasts were more virulent for mice than type A under most experimental conditions. Mice infected with type B yeasts grown in the light lived significantly longer than those with type B yeasts grown in the dark. Virulence differences of type A yeasts grown in continuous fluorescent light versus total darkness were not statistically significant.