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FINDINGS: West Nile virus causes a dengue-like illness usually lasting less than a week. Fever may be biphasic, and rash is common. Meningoencephalitis is a complication. [CCDM, p. 45-8] It is estimated that about 80% of WNV infections are asymptomatic, 20% are "West Nile Fever," and less than 1% are CNS infections. Encephalitis usually occurs in people who are older or chronically ill. In the last two years, more cases of flaccid paralysis have been reported. Paralysis often affects young, healthy patients and may precede the symptoms of headache and fever. Paralysis may involve one extremity only; it is associated with pain but not numbness. [www.cdc.gov] The symptoms of West Nile fever are myalgia, fever, rash, lymphadenopathy, headache, weakness, backache, conjunctival injection, and pharyngitis. Other findings observed in outbreaks of WNV infections are confusion, stiff neck, diarrhea, and leukocytosis or leukopenia. Complications include pancreatitis, myocarditis, optic neuritis, radiculitis, myelitis, and hepatitis. [ID, p. 2129] Other findings in West Nile fever are hepatomegaly (20% of patients), splenomegaly (10% of patients), liver dysfunction, abdominal pain, cough, and fatigue. Patients with neurological disease may have ataxia, tremors, and rigidity. [PPID, p. 1940] EPIDEMIOLOGY: Transmission by transfusion and percutaneous occupational exposure has been reported. WNV infections are an occupational hazard for people working outside when mosquitoes are biting. Turkey breeder farm workers have become infected with WNV, but the mode of transmission is not known. [www.cdc.gov] Birds are the reservoir for WNV. Other animals that may become infected include horses, dogs, camel, cows, donkeys, water buffalo, sheep, bats chipmunks, squirrels, rabbits, rats, and skunks. [ID, p. 2128] |
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