Venezuelan equine encephalitis is a flu-like illness. Some patients have pharyngitis and painful cervical lymphadenopathy. Case fatality rates range from 0.2-1% for infected patients to 10-25% for patients with encephalitis. Reservoirs for epizootic cycles are mosquitoes, horses, and humans.
CASES/YEAR
1 (US); 100 (Global)
OTHER NAMES
VEE; Venezuelan equine encephalomyelitis virus disease; Venezuelan equine fever;
INCUBATION
Usually 3-14 days; [CCDM]
INITIAL SYMPTOMS
Flu-like illness with headache, fever, myalgia, retro-orbital pain, vomiting, and injection of conjunctiva and pharynx; [CCDM, 19th Ed., p. 49] Some patients have pharyngitis and painful cervical lymphadenopathy. [PPID, p. 1243]
COMMENTS
FINDINGS:
Most patients have a mild illness lasting 3-5 days. A biphasic fever is seen in some cases. Pneumonia may occur. [CCDM, 19th Ed., p. 49-51] Infection is associated with leukopenia and elevated liver enzymes. [PPID, p. 1243] Pharyngitis, cervical lymphadenitis, and abdominal tenderness are common. [Guerrant, p. 523]
EPIDEMIOLOGY:
Case fatality rates range from 0.2-1% for infected patients to 10-25% for patients with encephalitis. [PPID, p. 1243] Reservoirs for enzootic cycles are mosquitoes and rodents. Reservoirs for epizootic cycles are mosquitoes, horses, and humans. Laboratory personnel may become infected by inhalation, and a vaccine has been used to protect these workers. A vaccine for horses is commercially available. [CCDM, 19th Ed., p. 49-51] "The prevention of epizootic Venezuelan equine encephalitis depends on vaccination of horses with the attenuated TC-83 vaccine or with an inactivated vaccine prepared from that strain." [Harrison ID, p. 964]
DIAGNOSTIC
Culture; PCR; Paired sera; IgM detectable within the first weeks after onset; [CCDM] Detect specific IgM antibody in serum or CSF; PCR of blood or pharynx positive after 7 days of illness; [PPID, p. 1243]
SCOPE
Central and South America; [PPID, p. 1243]
SIGNS & SYMPTOMS
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>fatigue, weakness
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>fever
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>fever, biphasic or relapsing
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>myalgia
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E dysphagia
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E pharyngitis
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G abdominal pain
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G diarrhea
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G liver function test, abnormal
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G nausea, vomiting
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H leukopenia
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H lymphadenopathy
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H thrombocytopenia
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N headache
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N lethargy
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N seizure
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N stiff neck
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O conjunctivitis, acute
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*cranial neuropathy
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*encephalitis
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*meningitis
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*paralysis
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*pneumonia
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*pneumonitis
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*stupor, coma
RESERVOIR
Horses, Rodents, Human
RISK FACTORS
- Travel to endemic area
- Victim--air release of infectious agents
- Work in a medical or research lab
TREATMENT
No antimicrobial therapy; [CCDM]
REFERENCES FOR CASES/YEAR
1. (US) Rare cases in children; [Cecil, p. 2229t]
2. (Global) Last outbreak was in Venezuela and Columbia in 1995 with 85,000 cases; [Cecil, p. 2231] Annual number of cases is unknown. [Harrison ID, 2nd Ed, p. 1038t] Guesstimate: 100;