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The following text is from an archived Red Book® edition and may not reflect current recommendations or information. To view the current edition, click here.
Section 3. Summaries of Infectious Diseases
Arboviruses
(Including California Encephalitis [Primarily La Crosse], Eastern and Western Equine Encephalitis, Powassan Encephalitis, St Louis Encephalitis, Venezuelan Equine Encephalitis, West Nile Encephalitis, Colorado Tick Fever, Dengue, Japanese Encephalitis, and Yellow Fever)Clinical Manifestations
Etiology
Epidemiology
Diagnostic Tests
Treatment
Isolation of the Hospitalized Patient
Control Measures
CLINICAL MANIFESTATIONS: Arboviruses (arthropodborne viruses) are spread by mosquitoes, ticks, or sandflies and produce 4 principal clinical syndromes: (1) central nervous system (CNS) infection (including encephalitis, aseptic meningitis, or myelitis); (2) an undifferentiated febrile illness, often with rash; (3) acute polyarthropathy; and (4) acute hemorrhagic fever, usually accompanied by hepatitis. Infection with some arboviruses produces perinatal illness.
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Selected arboviruses transmitted in the Western hemisphere associated with central nervous system involvement are shown in Table 3.1 (p 200). Eastern equine encephalitis (EEE) virus is the most severe arthropodborne encephalitis in the United States. The other principal arboviruses transmitted in North America mainly produce asymptomatic infections. When present, clinical illness ranges in severity from a self-limited febrile illness with headache and vomiting (especially in children) to a syndrome of aseptic meningitis or acute encephalitis. The La Crosse (LAC) virus produces aseptic meningitis or encephalitis with acute seizures and focal findings in more than 25% of cases and stupor or coma in 50%, but death occurs in less than 1%. Eastern equine encephalitis typically is a fulminant illness leading to coma and death in one third of cases and serious neurologic sequelae in another one third. The clinical severity of western equine encephalitis (WEE) is intermediate, with a case-fatality rate of 5%; neurologic impairment is common in infants. Powassan encephalitis is associated with long-term morbidity and has a case-fatality rate of 10% to 15%. Characteristics of symptomatic infection caused by St Louis encephalitis (SLE) include confusion, fever, headache,
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