Experimental Rubella in Human Volunteers

Abstract

Summary: Typical rubella has been produced by the inoculation of human volunteers by the respiratory route. The agent responsible remained viable in the presence of 200 O. U. of penicillin per ml and the evidence suggests that it was filterable through an 800 mμ membrane. It is therefore probably a virus. The virus was present in throat washings taken on the first day of the rash. The virus remained infective for at least 90 days when stored as frozen throat washings at −70 C. The incubation period in human subjects infected by inhalation ranged from thirteen to twenty days to the appearance of a rash. Lymphadenopathy preceded the onset of the rash by up to six days in some instances. Susceptible individuals were infected by contact with the experimental disease. Symptoms were not induced in any of nine subjects giving a history of rubella six to nine years previously. Evidence is presented for the existence of subclinical or unnoticed rubella. It is concluded that immunity to rubella is of high grade and persists probably beyond the six to nine year period covered by these results. There is no evidence that the artificially induced disease differs in any way from natural rubella and the immunity produced should be equally effective.