The Flu and Richard Pfeiffer

For decades, scientists puzzled over which influenza virus was actually responsible for the Russian pandemic. Finally, in 2014, phylogenetic techniques (examining evolutionary patterns of the virus genes) and seroarcheologic techniques (measuring antibodies likely present in people at various points in time) were applied to the question of which virus caused the Russian flu of 1889–1892. Thus, Pfeiffer’s proclamation that his bacillus caused influenza was finally proven wrong. His identification of Bacillus influenzae in the respiratory tract, however, was a major contribution to the scientific understanding of bacterial infections and moved the field of bacteriology forward in allowing other investigators to unearth its full potential as an important human pathogen. Further, in the course of his studies of B. influenzae, Pfeiffer pioneered the field of nutritional requirements of bacteria. Finally, Pfeiffer’s identification of Haemophilus influenzae launched subsequent studies of the causes of bacterial meningitis and initiated in-depth explorations of bacterial meningitis-causing pathogens that ground our concepts of pathogenesis, and guide our management, of the infection.