Which disease caused the largest U.S. Army epidemic during the Spanish-American War?

Typhoid fever caused the largest U.S. Army epidemic during the Spanish-American War.

The epidemic spread through crowded American training and assembly camps in 1898, where sanitation was poor and medical officers had limited understanding of how contaminated water, food, and hands transmitted the disease. Soldiers often became sick before reaching the battlefront, making disease a greater threat than Spanish gunfire.

About 21,738 U.S. soldiers contracted typhoid fever, representing roughly 82 percent of all reported illness among sick soldiers. Approximately 1,590 died, and typhoid accounted for about 87 percent of disease deaths in the Army’s assembly camps. Every regiment was affected, with camps in the United States proving especially dangerous.

Yellow fever, malaria, and dysentery also afflicted American troops, particularly in Cuba, but none matched typhoid’s overall impact on the Army. The crisis exposed severe weaknesses in military sanitation and helped prompt reforms in camp hygiene, medical organization, and disease prevention.