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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 endemic in the sylvatic setting in sub-Saharan Africa and the tropical regions of South America. In the intermediate or savannah cycle, the infection is transmitted to humans via mosquitoes that bite infected monkeys or other humans living or working in jungle border areas in Africa.