Symptoms of severe illness include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Severe illness can occur in people of any age; however, people over 60 years of age are at greater risk for severe illness if they are infected 1 in 50 people. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk.
Recovery from severe illness might take several weeks or months. Some effects to the central nervous system might be permanent. About 1 out of 10 people who develop severe illness affecting the central nervous system die.
Diagnosis See your healthcare provider if you develop the symptoms described above. Mosquito Control State DEP and county mosquito control professionals have been using Bti, a naturally occurring bacteria, to kill mosquito larvae for years.
This material is now becoming widely available for you to buy and use yourself at home. Bti can be purchased in small, donut-shaped form, often called "mosquito dunks", which are useful in small areas of standing water, such as a birdbath or small puddle of water that may gather in a low spot on your property. A granular form of Bti is available, and effective for larger areas, such as backyard ponds. Bti can be purchased in many lawn and garden, outdoor supply, and home improvement stores.
The great thing about this bacteria is that it kills only mosquito and black fly larvae. It is not harmful to people, pets, aquatic life such as fish or plants. The best way to control mosquitoes is still to get rid of standing water on your property.
And, make sure you follow all label instructions carefully if you use Bti at home. The virus is transmitted from avian reservoir hosts by mosquitoes and infrequently by other bloodsucking insects to horses, humans and a number of other mammals. Horses and humans are considered to be dead-end hosts for WNV; the virus is not directly contagious from horse to horse or horse to human.
Thus vaccination for West Nile virus is recommended as a core vaccine and is an essential standard of care for all horses in North America. Authors Ann M. Why do we need this? Entering your postal code will help us provide news or event updates for your area. Even if you're infected, your risk of developing a serious West Nile virus-related illness is very small.
And most people who do become sick recover fully. You're more likely to develop a severe or fatal infection based on:. Your best bet for preventing West Nile virus and other mosquito-borne illnesses is to avoid exposure to mosquitoes and remove standing water, where mosquitoes breed. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press. This content does not have an English version. This content does not have an Arabic version. Overview A mosquito-transmitted virus causes most cases of West Nile infection.
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West Nile virus transmission cycle When a mosquito bites an infected bird, the virus enters the mosquito's bloodstream and eventually moves into its salivary glands. WNV can be severe for people older than 60 years and people with weakened immune systems. If diagnosed and treated quickly, the outlook for West Nile virus recovery is good. If you have West Nile virus, you will typically show the first virus symptoms within three to 14 days of being bitten. West Nile virus symptoms vary in severity.
Severe symptoms can include:. A severe infection can last for several weeks. In rare cases, a severe infection can cause permanent brain damage. Mild forms of West Nile virus may be confused with the flu. Symptoms include:. Infected mosquitoes usually spread the West Nile virus. The mosquito first bites an infected bird and then bites a human or another animal.
In rare cases, blood transfusions, organ transplants, breastfeeding, or pregnancy can transfer the virus and spread the illness. Anyone bitten by an infected mosquito can get West Nile virus. However, less than one percent of people who are bitten develop severe or life-threatening symptoms. Age is one of the most significant risk factors for developing severe symptoms from a West Nile infection.
In most cases, your doctor can diagnose West Nile virus with a simple blood test. This can determine whether you have genetic material or antibodies in your blood associated with West Nile virus.
If your symptoms are severe and brain-related, your physician may order a lumbar puncture. Also known as a spinal tap, this test involves inserting a needle into your spine to extract fluid. West Nile virus can elevate the white blood cell count in the fluid, which indicates an infection. MRI and other imaging scans can also help detect inflammation and brain swelling.
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