Followup of Blastomycin Sensitivity in an Epidemic Area

Abstract

In a 2-year followup of a survey performed in an epidemic area of North American blastomycosis in Grifton, North Carolina, 43 persons were studied with skin and complement-fixation tests to blastomycosis and histoplasmosis. Blastomycin (a Blastomyces vaccine) skin sensitivity was found to be retained for as long as 2 years in the absence of clinical disease or histoplasmin sensitivity. One third of the previous blastomycin reactors and 91% of the positive blastomycosis complement-fixation tests reverted to negative over the 2-year period. Loss of reactivity to histoplasmin was also observed. It was postulated that changes in, or loss of, reactivity to these antigens with the passage of time may serve to help differentiate the cross-reaction from the sub-clinical or clinical dual infection.