Relationship between “purulent bronchitis” in military populations in Europe prior to 1918 and the 1918–1919 influenza pandemic

Purulent bronchitis was a distinctive and apparently new lethal respiratory infection in British and American soldiers during the First World War. Mortality records suggest that purulent bronchitis caused localized outbreaks in the midst of a broad epidemic wave of lethal respiratory illness in 1916-1917. Probable purulent bronchitis deaths in the Australian Army showed an epidemic wave that moved from France to England. Purulent bronchitis may have been the clinical expression of infection with a novel influenza virus which also could have been a direct precursor of the 1918 pandemic strain.