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Malaria - and its cousin, yellow fever - had significant implications during the war and the debilitating consequences of the disease were already certain before the Civil War had started in earnest and well before its final history had been written.
Yellow fever is a serious, potentially deadly flu-like disease spread by mosquitoes. Characterized by a high fever and jaundice, it is most prevalent in certain parts of Africa and South America. The disease is not curable, but is preventable with the yellow fever vaccine.