Frequently Asked Questions about the West Nile Virus
Learn more about the West Nile Virus

1. What are the symptoms of West Nile Virus?
Most people who are infected with the West Nile virus will not experience symptoms, with only one fifth of those infected experiencing typical symptoms of the virus. These include fever, headache, and body aches, occasionally with a skin rash and swollen lymph glands. The symptoms of severe infection (West Nile encephalitis or meningitis) include headache, tremors, high fever, neck stiffness, stupor, disorientation, coma, convulsions, muscle weakness, and paralysis. One out of every 150 people infected with the disease will experience a severe form of the disease.
2. Does West Nile virus present great risk during pregnancy to a fetus?
It is not known yet whether West Nile virus conclusively harms the fetus as a result of infection. However, due to ongoing concerns that mother-to-child WNV transmission can occur with possible adverse health effects, pregnant women should take precautions to reduce their risk for West Nile virus by avoiding places where mosquitoes live and wearing protective clothing.
3. How is West Nile Virus transmitted from person to person?
West Nile virus is primarily spread through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. The virus eventually spreads to the mosquito’s salivary glands and during feedings the virus may be injected into humans and animals.

During the 2002 West Nile epidemic it became apparent that there were alternative methods of transmission as well, although it is important to note that these other methods of transmission represent a very small proportion of cases and are very rare overall. The West Nile Virus has been transmitted through transplanted organs, although this is rare. It also appears that West Nile virus can be transmitted through breast milk. Laboratory workers are also at risk, as two cases have been reported. However, the risk of all these other types of transmissions is very unlikely to occur in the general populace.
4. How is West Nile encephalitis treated?
Although there is no specific treatment for a West Nile virus infection, in more severe cases, intensive supportive therapy might be utilized involving hospitalization, airway management, respiratory support, intravenous fluids, prevention of secondary infections, and nursing care.
5. How many people with West Nile virus actually die?
The fatality rate among those who catch severe illness due to West Nile Virus ranges from 3% to 15%. It is important to note that less than 1% of all people infected with the virus develop severe illness.
6. What makes the West Nile virus such a potent disease among people?
The West Nile virus is potent because it multiplies in the person's blood system and crosses the blood-brain barrier to reach the brain, interfering with normal central nervous system functioning and causes inflammation of brain tissue.