Clinical Features of Yellow fever
المؤلف:
Baijayantimala Mishra
المصدر:
Textbook of Medical Virology
الجزء والصفحة:
2nd Edition , p293-294
2025-12-18
38
Yellow fever causes a wide range of symptoms varying from no symptoms to mild febrile illness to severe disease with multiorgan involvement with a high fatality rate.
Incubation period of YF is 3–6 days from the day of mosquito inoculation to development of symptoms with a median of 4 days. Clinical manifestations of YF has been classically divided into three different phases, namely; infection, remission and intoxication (Fig. 1).
Fig1. Time course of yellow fever virus infection
Period of infection: This includes the onset of symptoms which is typically abrupt and presents with fever, headache, malaise, vomiting. This period corresponds with peak viremia during which YFV can be detected in blood by virus isolation or molecular methods. During this period, the person is infectious to mosquitoes. It lasts for about 3–6 days. Majority of the infected persons recover within one week of initial illness.
Period of remission: Some patients may experience a short period of remission following the infection phase with resolution of fever and improvement in symptoms and signs. Most of the patients recover during this phase.
Period of intoxication: A subset of 15% YFV infected patients develop severe form of disease called phase of intoxication. This phase is marked by return of fever with severe epigastric pain, nausea, vomiting, jaundice (causing yellow skin from which the name yellow fever is given). Hepatic dysfunction, renal failure and bleeding diathesis leading to the manifestations of hemorrhagic fever are the prominent clinical features of severe YF disease. Hemorrhagic manifestations occur due to consumptive coagulopathy and reduce production of clotting factors. Hepatorenal failure along with circulatory collapse leads to metabolic disturbances, coma and death. About 20–50% of patients who enters the period of intoxication die within 7–10 days.
This phase is characterized by absence of viremia and detectable anti-YF antibodies.
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