What is West Nile virus?
West Nile virus is a flavivirus commonly found in Africa, West Asia, the Middle East, and now the United States. It is closely related to the St. Louis encephalitis virus found in the United States. The West Nile virus can infect humans, birds, mosquitoes, horses, and some other mammals.
Where did West Nile virus come from?
West Nile virus has been found commonly in humans, birds, and other animals in Africa, Eastern Europe, West Asia, and the Middle East, but until 1999 there had not been a documented case in the Western Hemisphere.
How do people get infected with West Nile virus?
The route of human infection with West Nile virus is through the bite of an infected mosquito. Mosquitoes become infected when they bite an infected bird and the virus eventually finds its way into the mosquito's salivary glands. If the infected mosquito then bites a human, the virus may be injected into that person's bloodstream where it can multiply and possibly cause illness. Animals can also be infected in this manner.
If I live in an area where birds or mosquitoes with West Nile virus have been reported and a mosquito bites me, am I likely to get sick?
No. Even in areas where the virus has been found, very few mosquitoes are actually infected with the virus. If a mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chance that you will become severely ill from any one mosquito bite is extremely small.
Can you get West Nile infection from another person?
No. West Nile infection is NOT transmitted from person-to-person. For example, you cannot get West Nile virus from touching or kissing a person who has the disease, or from a health care worker who has treated someone with the disease.
Can West Nile virus be transmitted through breast milk?
There was a confirmed case of West Nile virus transmission through breast milk in Michigan in 2002. However, the American Academy of Pediatricians and the American Academy of Family Physicians continue to recommend that infants be breast fed for the first year of life.
Are there any other ways that West Nile virus can be transmitted?
The Centers for Disease Control and Prevention is conducting an ongoing investigation on transmission through blood and organ donation. Donated blood is currently tested for WNV antibodies and if the blood tests positive for the virus it is excluded from the blood supply.
What are the symptoms of West Nile virus infection?
Most people who are infected with the West Nile virus will not become ill. It is estimated that 20% of the people who become infected will develop mild symptoms of infection including fever, headache, and body aches, and occasionally a skin rash on the trunk of the body and swollen lymph glands.
The symptoms of severe infection (West Nile encephalitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. It is estimated that one in 150 persons infected with the West Nile virus may develop a more severe form of disease.
If you are concerned about symptoms you should contact your doctor.
What is the incubation period (i.e., time from infection to disease symptoms) in humans for West Nile infection?
Usually three to 14 days.
How long do symptoms last?
Symptoms of mild disease will generally last a few days. Symptoms of severe disease may last several weeks and neurological effects may be permanent.
How does West Nile virus cause severe illness and death in humans?
Following transmission by an infected mosquito, West Nile virus multiplies in the person's blood stream and may reach the brain. Once in the brain the virus interferes with normal central nervous system functioning and causes inflammation of brain tissue.
If a person gets a mild case of West Nile fever, does that person develop immunity to future infection by the virus?
Yes. It is assumed that immunity will be lifelong; however, it may decline in later years.
How is West Nile infection treated?
Treatment for infection is supportive care: rest, plenty of fluids, and pain medication as recommended by the person's doctor. All scheduled doctor appointments should be kept. In addition, infected individuals should continue to avoid being bitten by mosquitoes.
Is there a vaccine against West Nile infection?
No, but several companies are working on developing a vaccine.
Are there cases of West Nile virus infection in Kalamazoo County?
Yes. Kalamazoo County has had a total of five cases of West Nile Virus as of January, 2005. In 2004, there was one case of West Nile Virus in Kalamazoo County and a total of 16 in the state of Michigan.
Are some people more at risk than others?
Any person bitten by an infected mosquito is at risk. However, young children, persons over 50, and immune-compromised individuals are at higher risk for serious illness. Outdoor workers and sportsmen engaged in activities where there are large populations of mosquitoes may also be at higher risk due to their increased exposure.
What is the most effective mosquito repellent?
Mosquito repellents with DEET have shown to be the most safe and effective way to prevent mosquito bites. The active ingredient N,N diethyl-m-toluamide, or N,N diethyl-3-methylbenzamide, is referred to as DEET. Repellents containing DEET have an excellent safety record but sensitivities can occur, usually when the product is misused. Read label directions before using any products containing DEET. Citronella and Skin So Soft have mild repellent properties. However DEET products should be the choice when dealing with potential disease carrying mosquitoes.
Are insect repellents containing DEET safe?
For extensive information regarding DEET use on Children, visit the Michigan Government West Nile virus web site, www.michigan.gov/westnilevirus. In general:
Do not use DEET products on children under 6 months old.
For children between the ages of six months and two years, use products containing 10% DEET or less and apply only once per day.
For children between the ages of two and 12, use 10% DEET or less no more than three times per day.
The American Academy of Pediatrics recommends the following precautions be observed when using products containing DEET:
Do not allow children to apply DEET to themselves.
Do not spray DEET directly on children. Apply repellant to your own hands, put it on the child, then wash your hands.
Avoid applying DEET to a child's face and hands.
Do not apply DEET to skin damaged by sunburn, cuts or scrapes, or skin conditions such as psoriasis or eczema.
Wash treated skin and clothing after returning indoors.
If you are concerned, use products containing only 10% DEET on children.
Store repellents containing DEET out of the reach of children.
If DEET is swallowed, call the poison control center immediately at 1-800-222-1222, TTY 1-800-356-3232.
If you believe you or your child is having a reaction to DEET, wash it off immediately and call your doctor.
Where can I get information about the use of pesticide sprays for mosquito control?
The federal agency responsible for pesticide evaluation is the Environmental Protection Agency (EPA). See the EPA Web site, www.epa.gov/pesticides, for detailed answers to the questions about pesticides used for mosquito control.
How can I keep mosquitoes away from my home?
Many of Michigan's adult mosquitoes have long flight ranges; some will fly over five miles from their breeding area to seek suitable hosts. Keep vegetation cut short so as not to provide a hiding place. Eliminate sources of standing water, such as old tires, clogged gutters, birdbaths and tree stump holes. The use of aerosol pesticides will provide only temporary control of adult mosquitoes. Electronic bug "zappers", purple martins, and bats are not effective in the reduction of adult mosquito populations.
Can you get West Nile virus from eating game birds or animals that have been infected?
There is no evidence that West Nile virus can be transmitted to humans from eating infected birds or animals. In keeping with overall public health practice, and due to the risk of known food-borne diseases, people should always follow procedures for fully cooking meat from either game birds or animals.
Can you get West Nile virus directly from birds?
No. There is no evidence that a person can get the virus from handling live or dead infected birds.
What do I do if I find a dead bird?
All sick/dead bird sightings should be reported through the State of Michigan website.
Can you get infected with West Nile virus by caring for an infected horse/dog/cat?
West Nile virus is transmitted to humans by infectious mosquitoes. There is no documented evidence of person-to-person or animal-to-animal transmission of West Nile virus. Transmission is from an infected mosquito.
How many types of animals have been found to be infected with West Nile virus?
Although the vast majority of infections have been identified in birds, West Nile virus has been shown to infect horses, cats, bats, chipmunks, skunks, squirrels, and domestic rabbits.
More Questions?
If you have questions or need more information, e-mail us at pio@kalcounty.com.
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