The disease mainly affects the liver leading to midzone necrosis and is manifested by jaundice (hence the name "yellow" fever).
The incubation period is in the range of 3-6 days.
The phase of infection: this is characterized by fever, malaise, headache, retrobulbar pain, myalgia and flushing of the face. There may also be relative bradycardia.
The phase of remission: fever subsides for 4-5 days.
The phase of intoxication: The fever increases and the patient develops jaundice, hepatomegaly, ecchymoses and bleeding tendency. The kidneys may also become affected with acute tubular necrosis leading to renal failure.
A rising titre for the neutralizing antibody in serum establishes the diagnosis of infection. Other lab findings include hyperbilirubinemia, elevated liver enzymes.
Supportive measures with fluid replacement, blood transfusion and oxygen adminstration. Severe cases require admission to intensive care units. Nursing should occur under mosquito nets to prevent further infection of mosquitoes.
Travelers to endemic areas should be vaccinated with the chick embryo vaccine.