Two people have died and 14 are ill from a mosquito-born disease called West Nile fever, the Greek Health Ministry said on Tuesday. All the cases were diagnosed over the past 10 days in northern Greece and confirmed by laboratory tests, the ministry said. "There's no cause for panic. Most people don't show any symptoms, even when they are infected," said Anna Pappa, Deputy Professor for Microbiology at Aristotle University in the northern city of Thessaloniki. Symptoms are headaches and aching limbs, which pass off after a few days. People in the infected areas were advised to use insect repellants or creams. The West Nile virus mainly infects birds, but can also be passed on to humans through the bite of an infected mosquito.
WNV has three different effects on humans. The first is an asymptomatic infection; the second is a mild febrile syndrome termed West Nile Fever; the third is a neuroinvasive disease termed West Nile meningitis or encephalitis. The population proportion of these three states is roughly 110:30:1.
The second, febrile stage has an incubation period of 2 to 8 days followed by fever, headache, chills, diaphoresis (excessive sweating), weakness, lymphadenopathy (swollen lymph nodes), drowsiness, pain in the joints and symptoms like those of influenza or the flu. Occasionally there is a short-lived truncal rash and some patients experience gastrointestinal symptoms including nausea, vomiting, loss of appetite, or diarrhea. All symptoms are resolved within 7 to 10 days, although fatigue can last for some weeks and lymphadenopathy can take up to two months to resolve.
The more dangerous encephalitis is characterized by similar early symptoms but also a decreased level of consciousness, sometimes approaching near-coma. Deep tendon reflexes are hyperactive at first, later diminished. There are also extrapyramidal disorders. Recovery is marked by a long convalescence with fatigue.
More recent outbreaks have resulted in a deeper study of the disease and other, rarer, outcomes have been identified. The spinal cord may be infected, marked by anterior myelitis with or without encephalitis. WNV-associated Guillain-Barré syndrome has been identified and other rare effects include multifocal chorioretinitis (which has 100% specificity for identifying WNV infection in patients with possible WNV encephalitis), hepatitis, myocarditis, nephritis, pancreatitis, and splenomegaly.
10.08.2010
