Prognosis
Infection confers lasting immunity, and no case of reinfection has been documented.
There is a theoretical risk of increased severity of clinical illness in patients with genetic or therapy-induced (i.e., CCR5 inhibitor therapy such as maraviroc) absence of CCR5 chemokine receptors.
Asymptomatic infection
Many patients who acquire the infection have no or minimal symptoms compatible with a nonspecific viral illness, resulting in lifelong immunity. Previous infection with other flaviviruses (e.g., dengue) is believed to afford some cross-protection and increase the chance of a mild illness.
Period of infection
After an incubation period of 3 to 6 days, affected patients experience the abrupt onset of fever, chills, malaise, muscle aches, nausea, and dizziness. Mild jaundice may develop. After an illness lasting 2 to 6 days (average 3.5 days), 75% to 85% of patients recover without further signs or symptoms.[2]
Period of intoxication
In about 15% to 25% of affected patients, the illness reappears after an asymptomatic interval of 24 hours, usually in a more severe form with fever, jaundice, abdominal pain, renal failure, and bleeding. After an average of 7 to 10 days, up to 50% of those living in endemic areas, and up to 89% of travelers, who progress to the period of intoxication, die.[15][2]
Most patients who recover (typically after a 2- to 3-week illness) experience fatigue and weakness for several more weeks. Unless secondary renal tubular necrosis has occurred, liver and kidney function generally recover fully. Reinfection does not occur.
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