Infection secondary to the West Nile virus

Infectious disease caused by a virus from the flaviviridae family.

It is widely spread throughout the United States, Mexico, Central and South America, Africa, the Middle-East and Southern Europe.

It is transmitted by the bite of the culex mosquito, which bites birds and horses, as well as humans.

Most people infected are asymptomatic. When symptoms occur, they usually include general symptoms such as fever, headache, joint pain, body pain, digestive symptoms such as vomiting and diarrhoea, and it can go alongside skin rash. Although rare, there are cases with central nervous system (CNS) involvement in the form of high fever, severe headache, neck stiffness, tremors, convulsions, muscle weakness, numbness, muscle paralysis and low level of consciousness, which can lead to coma. In severe cases with CNS involvement, it can lead to the death of the patient.

The diagnosis of suspicion is clinical, as the symptoms coincide with the possibility of a mosquito bite in an endemic area for the disease. It is confirmed by a blood and/or cerebrospinal fluid test, where IgM antibodies specific for Nile virus are detected. Viral cultures and tests for virus RNA may also be performed.

Symptoms should be treated with antipyretics for fever, analgesics for pain and proper hydration.
In severe cases with CNS involvement, intubation and mechanical ventilation may be necessary to protect the airways in case of low level of consciousness or when flaccid paralysis affects the respiratory muscles.

There is no human vaccine to protect against the disease, so community-based mosquito control programmes are essential. At a personal level, it is advisable to use protective measures to avoid mosquito bites.