Etiology of Whooping Cough. ∗

Abstract

Three beliefs exist in regard to the etiology of whooping cough: That the disease is caused by H. pertussis, that the agent is a filtrable virus, or that both play a part. H. pertussis is practically always present in the disease and absent in health. 1 That the organism plays a most important rôle has been shown by occasional successful transmission experiments 2 , 3 , 4 and by reports of effective protection with suitable H. pertussis vaccine. 1 , 4 , 5 The recent description of intranuclear inclusion bodies 6 taken together with certain other considerations has led some^3,7 to believe that a virus plays either a specific etiological rôle or, accompanied by H. pertussis, acts as primary infective agent. Attempted transmission experiments with filtrates have been equivocal or negative. 3 , 4 Because of too recent isolation of the organism or of inoculation with filtrate shortly before 4 the few successful transmission experiments with H. pertussis are open to the criticism that a virus may have been present. It seemed necessary to devise experiments in which H. pertussis or virus effects were clearly separated. In this communication we are reporting successful whooping cought transmission by means of what we believe to be virus-free H. pertussis.

The newer knowledge of the phases of H. pertussis 8 , 9 and their precise differentiation by electrophoresis 10 provided the desired approach. When first isolated H. pertussis differs culturally, morphologically, serologically, and electrophoretically from older laboratory cultures. Leslie and Gardner call the former, Phase I, and the variations rapidly appearing on subculture, Phases II, III, IV. It is possible 9 , 10 that this change represents the well-known virulent (“S”) to avirulent (“R”) transition of other bacteria.