Why Did Black Soldiers Historically Have More Pneumonia Than White Soldiers in the U.S. Army?

Black U.S. Army soldiers had four times as much bacterial pneumonia as White U.S. Army soldiers during both the U.S. Civil War and World War I (WWI). Pneumonia case fatality rates were a third greater in Black soldiers during the U.S. Civil War, but were the same between the racial groups by WWI. During WWII, the use of antibiotics decreased bacterial pneumonia mortality rates 100-fold and apparently erased racial differences. Similar differences in bacterial pneumonia rates by racial group were observed in African colonial soldiers of the French and British Armies during WWI. Pneumonia rates in Indian, Filipino, and Puerto Rican soldiers suggested that genetic polymorphisms were not a decisive factor determining Black pneumonia mortality. Postmeasles pneumonias did not suggest an immune deficit in Black soldiers. Geographic focus of pneumonia in Black soldiers from the southern U.S. states and other tropical regions raises the possibility that increased bacterial pneumonia rates were related indirectly to malaria infections. Malaria remains a difficult-to-measure but potentially important mortality risk factor in pneumonia.