New York City Department of Health

Q: What is West Nile virus?
A: West Nile virus is a mosquito-borne virus that can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord).

Q: How is West Nile virus spread?
A: West Nile virus is spread to humans by the bite of an infected mosquito. A mosquito becomes infected by biting a bird that carries the virus. You or your child cannot get West Nile virus from a person who has the disease. West Nile virus is not spread by person-to-person contact such as touching, kissing, or caring for someone who is infected.

Q: Where did the West Nile virus come from?
A: Outbreaks of the West Nile virus have occurred before in Egypt, Asia, Israel, South Africa, parts of Europe and Australia. Before 1999, the West Nile virus had never before been found in the United States. The New York City Department of Health, the New York State Health Department, and the U.S. Centers for Disease Control and Prevention (CDC), are currently investigating how the West Nile virus got into New York City. The most likely explanation is that the virus was introduced by an infected bird that was imported or an infected human returning from a country where the virus is common.

Q: Can you get West Nile virus directly from birds?
A: West Nile virus cannot spread directly from birds to people. However, dead birds should not be handled with bare hands. Use gloves to carefully place dead birds in a double plastic bag and then place the dead birds in the outdoor trash.

Q: Besides mosquitoes, can you get West Nile virus directly from other insects or ticks?
A: Infected mosquitoes are the primary source for West Nile virus and caused the recent outbreak in the New York City metropolitan area. There is no information to suggest that ticks transmitted West Nile virus to patients in the New York area outbreak.

Q: What are the symptoms of West Nile virus?
A: In last year's outbreak, most people who were infected with West Nile virus had no symptoms or experienced mild illness such as a fever, headache and body aches before fully recovering. In outbreaks in other parts of the world, some persons also developed a mild rash or swollen lymph glands. In some individuals, particularly the elderly, West Nile virus can cause serious disease that affects brain tissue. At its most serious, it can cause permanent neurological damage and can be fatal. Encephalitis (inflammation of the brain) symptoms include the rapid onset of severe headache, high fever, stiff neck, confusion, loss of consciousness (coma), and muscle weakness. Death may result in some cases.

Q: Is a woman's pregnancy at risk if she gets West Nile encephalitis?
A: There is no documented evidence that a pregnant woman or her fetus are at increased risk due to infection with West Nile virus.

Q: How is West Nile encephalitis treated?
A: There is no specific therapy. In more severe cases, intensive supportive therapy is indicated, i.e., hospitalization, intravenous (IV) fluids and nutrition, airway management, ventilatory support (ventilator) if needed, prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care.

Q: Is there a vaccine against West Nile virus?
A: No.

Q: How long does it take to get sick if bitten by an infected mosquito?
A: Being bitten by an infected mosquito will not necessarily make you sick since most people who are infected with West Nile virus have no symptoms or experience mild illness. If illness were to occur, it would occur within 5 to15 days of being bitten by an infected mosquito.

Q: What should a person do if he/she thinks they have West Nile encephalitis?
A: If a person has signs of encephalitis, with fever, muscle weakness, and confusion, he or she should seek medical care as soon as possible.

Q: Who is at risk for getting West Nile encephalitis after being bitten by an infected mosquito?
A: Persons older than 50 years of age have the highest risk of severe disease.

Please Note: Some local hardware stores may carry a product called Mosquito Dunk that contains a larvicide - Bacillus thuringiensis israelensis (BTI) - for use in areas of standing water around the home. The City Department of Health recommends eliminating standing water around the home to reduce breeding sites for mosquitoes and warns that direct handling of larvicides may cause skin and eye irritation. If these products are purchased for home use, we recommend careful reading of the hazards label, directions, and details regarding storage and handling.

Q: What is the City doing to address the possible return of West Nile virus?
A: The New York City Department of Health, along with other City, State and federal agencies, has developed a comprehensive plan to reduce the risk of West Nile virus returning in 2000. The main goal of this plan is to decrease the number of adult mosquitoes by eliminating their breeding sites, where possible, and applying larvicides (to kill the immature larval form of the mosquito) to areas with standing water that can not be drained completely. The City will also regularly test adult mosquitoes and birds for West Nile virus throughout the spring and summer. If West Nile virus is found, focused and limited applications of pesticides may be needed to prevent the spread to people.

Q: Is the City planning to spray pesticides by plane or helicopter, as was done last year?
A: Reducing the adult mosquito population (adulticiding) with pesticides approved by the US Environmental Protection Agency will be done when necessary to prevent or address the potential for illness in the human population. The City is hopeful that with an early and aggressive campaign against mosquitoes, the need for aerial spraying of pesticides will be reduced. In addition, early warning systems to detect the spread of West Nile virus in birds and mosquitoes can help direct effective and targeted use of pesticides.

Q: What health risks are posed to people and pets from pesticides?
A: If pesticides are used, the products that will be applied will be used according to guidelines set by the U.S. Environmental Protection Agency. In the small amounts that they would be used, these pesticides would pose negligible risks to people and to pets. Some people may be more sensitive to pesticides and should closely adhere to the recommendations below. Avoiding exposure to pesticides will lessen the risk of any reactions, which may include eye irritation, rash or difficulty breathing. There could be an odor associated with pesticides, but it will pass in a few hours. Call the City's Poison Control Center at (212) POISONS or (212) 764-7667 for more information, if exposure to pesticides causes any adverse reactions.

Q. Will the public be notified in advance about spraying activities?
A: Residents will learn about spraying schedules through public service announcements, the media, the City's website, and a telephone information line.

Q: If I live in an area where birds or mosquitoes with West Nile virus have been reported, and I am bitten by a mosquito, am I likely to get sick?
A: No. Even in areas where mosquitoes do carry the virus, very few mosquitoes -- less than 1% -- are infected. The chances that any one bite will be from an infected mosquito are very small.

Q. I've gotten a mosquito bite. Should I be tested for West Nile virus?
A: No. Most mosquitoes are not infected with West Nile virus. Illnesses related to mosquito bites are rare, especially in New York City. However, you should see a doctor immediately if you develop symptoms such as high fever, confusion, muscle weakness, severe headaches, stiff neck, or if your eyes become sensitive to light. Patients with mild symptoms should recover completely, and do not require any specific medication or laboratory testing.

Q: Should I report dead birds to the Health Department?
A: The Department of Health is taking reports on dead bird sightings within New York City, especially crows and sparrows. While the Department of Health is interested in collecting information about dead birds as part of its efforts to understand West Nile virus, we will not be picking up every dead bird reported. The Department will only be collecting a small sample of the bird population. However, we encourage New York City residents to report all dead bird sightings on this line to assist the department's monitoring efforts.

If you do not receive a phone call from the Department of Health to arrange pick up of the dead bird within 24 hours of making the report or by the next business day, please dispose of the dead bird. West Nile virus cannot spread directly from birds to people, however dead birds should not be handled with bare hands. Use gloves to carefully place dead birds in a double plastic bag and then place the dead birds in the outdoor trash.