West Nile Infection

West Nile infection is a viral illness caused by the West Nile virus, a member of the flavi virus family, with varying characteristics; ranging from no symptoms to flu like symptoms with an associated red rash and frequent involvement of the central nervous system (meningoencephalitis) with headache, visual complaints, weakness, confusion and possibly paralysis or seizures.

Where does it occur?

It occurs worldwide but is primarily seen in Africa, North America, Europe, Middle East and India.

The most recent significant outbreak occurred in the United States and Canada starting in 1999 and has plateaued as of 2003.

How is it transmitted?

The virus is transmitted to humans through the bite of infected mosquitoes. Birds serve as a reservoir for the virus and their migration plays a role in successive spread of the virus from region to region.

Is it contagious from person to person?

It is not directly contagious from person to person through casual contact; however West Nile Virus can be spread through blood transfusions, organ transplantation, through the placenta to the unborn and via breast milk.

What is the risk for travelers?

The risk for travelers is generally low, however if there were to be areas undergoing a new outbreak the risk increases.

How soon after exposure will one develop symptoms?

Symptoms generally appear anywhere from 3 days to 2 weeks after exposure.

What are the signs and symptoms?

Symptoms start with classic flu like findings including fever, chills, body aches, muscle aches, joint pain and mild headache. Many subsequently develop a red flat or prickly rash; have abdominal pain with nausea, vomiting or diarrhea. Most of these symptoms resolve in a week to 10 days, although one may experience significant fatigue for weeks.

 A significant proportion of patients can develop more serious illness with central nervous system involvement (meningoencephalitis) characterized by severe headache, stiffness of the neck, and visual complaints of blurring, pain with looking at bright light and can progress to decreased level of consciousness, confusion and seizures. One can also sometimes see weakness of the muscles of the face or limbs.

The elderly and those with underlying complex medical problems seem to develop more severe disease. Recovery may take months and could be incomplete.

Are there any lab tests to diagnose the illness?

There are tests to detect antibodies (IgM/IgG) against the West Nile Virus in blood and spinal fluid. PCR tests and viral cultures are also available.

Is there any treatment?

There are no specific antibiotics against the virus; treatment is entirely supportive with fluids, rest, pain medications and rehabilitation.

What preventive measures can be taken?

Avoid travel to a region if it’s undergoing an epidemic, if in an area at risk for infection; prevent mosquito bites by following the following recommendations

 Avoid outdoor activities at dusk and dawn

Wear long sleeve clothing

Apply insect repellant containing at least 30% DEET to clothing and exposed skin areas

 Stay in accommodations with screens

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