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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.
Malaria grows and multiplies in the liver, and yellow fever can lead to liver failure (the yellow in the name comes from one of its most obvious symptoms â jaundice). Both diseases can be prevented by oral medication and vaccination respectively.