A new study of West Nile virus and its survivors shows that those who are infected may never fully recover from it.
The main route of human infection with West Nile virus is through the bite of an infected mosquito. It 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. In infected individuals the ratio between the three states is roughly 110:30:1.
The second, febrile stage has an incubation period of 3-8 days followed by fever, headache, chills, diaphoresis, weakness, lymphadenopathy, and drowsiness. 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 7-10 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.
About 108 patients were examined during a 5-year period of study in attempt to single out outcomes and rates of recovery.
According to the research, the number of participants who had symptoms (second and third stages) and didn’t recover from the infection at the end of the first year constituted 60%. About 40% of patients showed symptoms 5 years after infection.
The researcher explained that on the whole, the recovery is traced down in the first two years, but if a patient hasn’t shown any recovery signs by that time, they are likely not to recover at all.