THE EPIDEMIOLOGIC association of infection of the upper respiratory tract and primary atypical pneumonia has been reported from many sources.1 Recently, serologic studies have demonstrated a direct causal relation between these diseases.2 During the third epidemic of primary pneumonitis in Minnesota, which is reported elsewhere,3 I observed for the first time babies ill with pneumonitis in the initial twenty-four hours of life. The mothers of several of these babies had evidence of infection of the upper respiratory tract at the time of delivery or shortly thereafter. This observation suggested that a common agent may be responsible for two seemingly different infections in which similar pathologic changes were observed. In the pharyngeal epithelium of both the mother and her baby there were many typical cytoplasmic inclusion bodies.
The frequent association of the common cold and atypical pneumonia is well known. An epidemiologic report by the Commission on Acute