With the increasing incidence of primary atypical pneumonia in recent years it has become desirable to establish an etiologic diagnosis whenever possible. It is only during the past decade that this disease has come to be recognized as a definite clinical entity. Numerous reports concerning this condition are to be found in the current literature, most of which have come out of military establishments. Owen1 reviewed the literature concerning primary atypical pneumonia and noted that over 1,750 cases had been reported from military posts since 1935. To these he added another 738 cases occurring at Scott Field during 1942. He also was able to find over 1,100 cases originating from civilian sources. It is significant that most of the reports available are concerned with epidemic outbreaks of the disease showing seasonal variations, being most frequent in the spring and late fall.
Atypical pneumonia occurs in a sporadic form as
LEVINSON DC, GIBBS J, BEARDWOOD JT. ORNITHOSIS AS A CAUSE OF SPORADIC ATYPICAL PNEUMONIA. JAMA. 1944;126(17):1079-1084. doi:10.1001/jama.1944.02850520021009