Studies of the Etiology of Influenza

For many years the etiology of influenza has been the subject of an interesting and continuous discussion. A number of microscopically visible organisms have been assigned a certain causative relationship to this disease. The most important of these microorganisms is H. influenzae, the significance of whose relationship to influenza was first brought out by Pfeiffer. This organism has continued to hold a prominent position on the stage of debate concerning the disease. Another question that has led to much discussion is the degree of uniformity of nature of the pathological and clinical entity described as influenza. Interest in this regard has largely centered upon the identity or non-identity of the so-called pandemic and inter-pandemic forms of the disease. Clinically, examples of the disease in pandemic and in inter-pandemic periods may resemble each other so closely as to be indistinguishable. Whether they are the same condition from an etiologic standpoint can not, however, as yet be answered. In recent years, with increasing knowledge of filterable viruses, this group of micro-organisms has been prominently considered in discussions of the etiology of influenza. Some evidence, , , , has already been brought out tending to implicate them in the disease and it is with this aspect of influenza that the present work is concerned. During an outbreak of influenza of the inter-pandemic type in the winter of 1930, an effort was made to communicate the disease to chimpanzees by means of bacteria-free filtrates of nasopharyngeal washings obtained from patients with typical attacks of the disease. The washings were obtained during the first 36 hours of the attack, passed rapidly through Seitz filters and inoculated intranasally in chimpanzees.