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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.
According to the CDC, yellow fever is a mosquito-borne viral disease present in Africa and South America. The infection can range from mild to severe. Vaccination is the best protection against this virus. Mild symptoms of yellow fever include: fever, nausea, vomiting, headache, abdominal and muscle pains.