The Relation of Influenza Virus and Bacteria in the Etiology of Pneumonia 12

Abstract

Evidence is accumulating that influenza virus plays a role in the etiology of certain pneumonias generally considered to be primarily bacterial in origin. The earliest recorded observations (1, 2) describe influenza as a mild self-limited disease of the upper respiratory tract which progressed occasionally in certain individuals to produce more serious symptoms involving the pulmonary tissue. Soon after the discovery of bacteria, clinicians (3) pointed out that pneumonia caused by streptococci, staphylococci and pneumococci often followed symptoms of influenza.During the pandemic of 1918 influenza was frequently complicated by bacterial pneumonia. Certain investigators (4, 5) believed that the primary disease was of unknown virus etiology and that the pulmonary involvement was a manifestation of the secondary invasion of the respiratory tissues by pathogenic organisms.Epidemiological data (6-10) show a significant increase in pneumonia deaths accompanying and following epidemics of clinical influenza. Other similar data (11,12) indicate that localized epidemics of pneumococcus pneumonia have been associated with outbreaks of clinical influenza.Laboratory evidence (13-22) on clinical cases of bacterial pneumonia in man and experiments on laboratory animals (23-28) during the past decade have further supported these observations.The studies reported herein show that there was a simultaneous infection with pneumococci and influenza virus in about one-half of the human cases of lobar pneumonia studied during an influenza epidemic. Such mixed infections were also observed during interepidemic periods.

The relationship between influenza and pneumonia

“…The results of this investigation are in general similar to those of the only other large-scale studies on pneumonia and influenza yet reported (Finland et al 1948;Maxwell et al 1949 A point of contrast between the results of the present investigation and those of the Baltimore workers lay in the nature of the bacteria present in the sputum or lung. All of the virus-positive cases of pneumonia identified in Baltimore during the epidemic yielded pneumococci, whereas the staphylococcus was an important organism in our own cases and particularly in the fatal illnesses.…”

“…Several observers have drawn attention recently to a possible connexion between influenza and pneumonia (Commission on Acute Respiratory Diseases, 1945;Finland, Ory, Meads & Barnes, 1948;Maxwell, Ward & van Metre, 1949). It has of course long been known that a general relationship exists between influenza and pneumonia in that an increase in incidence of pneumonia occurs during outbreaks of influenza, but the exact role of the virus infection in such cases is obscure.…”

Studies on Influenza in the Pandemic of 1957-1958. Ii. Pulmonary Complications of Influenza*†

“…In one of these patients the effusion was present prior to admission. Typical X-ray pictures are presented in Figures 17,19,20 Cough, chest pain, dyspnea, and cyanosis graded in severity from 0 to + + +. 224 findings.…”

Insights into the Interaction between Influenza Virus and Pneumococcus

“…They described the recovery of virus from a febrile man who then developed pneumococcal pneumonia 7 days into his convalescence and died (6). Once the viral etiology of influenza was firmly established, a series of detailed studies on the pathology, bacteriology, and epidemiology of bacterial pneumonia during influenza followed over the next decade (47,97,120,132,145,156). Influenza A and B viruses were both shown to predispose to bacterial infections, with S. pneumoniae and S. aureus as the most often cited invaders.…”