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West Nile Virus Questions Answered

5. Should I continue breastfeeding if I have symptoms of West Nile virus?

At least one woman appears to have passed West Nile virus to her child during breastfeeding. This appears to happen only rarely.

The benefits of breastfeeding far outweigh the potential risk of West Nile infection to an infant.

6. What are the chances of dying from West Nile virus infection?

The odds of getting the most severe forms of West Nile disease are about one in 150. The overall death rate in severe disease is about 10%. That makes the overall odds of dying from a West Nile infection about one in 1,500.

These odds aren't the same for everyone. People over age 50, especially those who are elderly, are more likely to suffer severe consequences from West Nile infection.

7. How does West Nile virus actually cause severe illness and death in humans?

West Nile virus causes severe disease when it crosses the blood/brain barrier and infects the brain and spinal cord. The virus disturbs normal brain function -- including disruption of the nerve impulses needed for breathing -- which can be fatal.

8. Should people avoid donating blood or getting blood transfusions or organ transplants?

Blood is lifesaving and often in short supply. Donating blood is safe, and we encourage blood donation now and in the future. Approximately 4.5 million persons receive blood or blood products annually. Although persons needing blood transfusions or organ transplants should be aware of the risk for WNV infection, the benefits of receiving needed transfusions or transplants outweigh the potential risk for WNV infection.

9. How do health care providers test for West Nile virus?

If your doctor suspects you have a West Nile virus infection, he or she will send a sample of your blood to a lab for tests. The most common tests look for antibodies against the virus, showing that you've recently been infected.

If you have symptoms of more severe disease, your doctor may perform a spinal tap to collect spinal fluid. As with blood, the spinal fluid sample is sent to a lab for tests.

10. Who is at risk for getting West Nile virus infection?

Mosquitoes carrying West Nile virus are found in all of the lower 48 states. Mosquitoes are most plentiful in late summer. West Nile season usually peaks in August and September.

People who spend a lot of time outdoors are at highest risk of infection. The mosquitoes that transmit West Nile virus are most active at dawn and dusk. Being outdoors during those hours increases the risk of infection.

People over age 50 are more likely to develop symptoms of West Nile disease, but it's not clear whether older people are more susceptible to infection.

Infants are not at higher risk of West Nile virus infection. And pregnancy does not increase a woman's risk of infection.

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