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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.
Sylvatic (or jungle) yellow fever: In tropical rainforests, monkeys, which are the primary reservoir of yellow fever, are bitten by wild mosquitoes which pass the virus on to other monkeys. 1  Occasionally humans working or travelling in the forest are bitten by infected mosquitoes and develop yellow fever.