Disseminated Necrosis of the Pulmonary Capillaries in Influenzal Pneumonia

The Pathology of Influenza Virus Infections

“…Most notable among them are the classic 1918 pandemic studies by Goodpasture (75) Wolbach described the hyaline membranes and the diffuse alveolar damage (21). LeCount described the focal capillary and small vessel thromboses typical of influenza viral pneumonia (77). MacCallum (72) and Winternitz et al (20) confirmed the above observations and described the underlying primary pulmonary lesion as most probably caused by an unknown nonbacterial (viral) agent.…”

“…This dilatation is responsible for the diffuse red color of the affected areas (20). Fibrinous capillary thrombi, first described by LeCount in 1919, are found in both the walls of alveolar ducts and in the alveolar septa (77). Leukocyte infiltration of the hyperemic alveolar septa is always present in the early stages of influenza virus pneumonia.…”

“…Necrosis of the alveolar wall may be a result of capillary thrombosis (77). The extent and number of necrotic sites vary.…”

“…,Klotz (76), LeCount(14,77), MacCallum (72), Opie et al(71,74),Walker (78),Winternitz et al (20),Wolbach (21), and Wolbach & Frothingham(79).Even though the first isolation of human influenza virus did not occur until 1933 (80), many pathologists had long suspected an underlying primary influenza viral pneumonia could be described separately from secondary bacterial pneumonias. Many pathologists in 1918 rejected the hypothesis that Bacillus (now Haemophilus) influenzae (Pfeiffer's bacillus) was the causative agent of influenza because in a number of series it was recovered in only a minority of cases at autopsy (81).Wolbach performed large autopsy studies in Boston and at nearby Camp Devens during the pandemic (21) and in 1923 wrote, Pathologists who have reported on the pulmonary lesions have not always endeavored to separate the lesions due to the virus of the epidemic and those dependent on the complicating organisms.…”

The 1918 Influenza Pandemic: Insights for the 21st Century

“…Clinical and autopsy series [22][23][24][25][26][27][28][29][30][31][32][33] suggest that excess influenza deaths (i.e., deaths above the expected background level for influenza) during 1918-1919 seem to have been associated with 2 overlapping clinical-pathologic syndromes (figure 1). The most common appears to have been an acute aggressive bronchopneumonia featuring epithelial necrosis, microvasculitis/vascular necrosis, hemorrhage, edema, and widely variant pathology in different parts of the lung, from which pathogenic bacteria could usually be cultured at autopsy (figure 1; also see [28]).…”