Most Common Illnesses You Get From Mosquito Bites

West Nile Virus

Most people who get West Nile virus don't have any symptoms. About 1 in 5 will have a fever and other flu-like symptoms. Feeling worn out could take months to go away completely. A few people get a more serious infection that causes brain swelling, or meningitis. There's a very small chance you could die.

People in 48 of the 50 U.S. states, Africa, Europe, the Middle East, and West and Central Asia have had West Nile.

Encephalitis

Mosquitoes can pass on viruses that cause inflammation around your brain and spinal cord. (The brain swelling with a serious West Nile infection is a kind of encephalitis.)

What type you could get depends on where you are:

  • LaCrosse -- the 13 states east of the Mississippi River
  • St. Louis -- throughout the U.S., especially Florida and Gulf of Mexico states
  • Eastern Equine -- Atlantic, Gulf Coast, and Great Lakes states; the Caribbean; Central and South America
  • Western Equine -- states west of the Mississippi River, areas of Canada and Mexico
  • Japanese -- Asia and the Western Pacific

Your doctor can give you medicine to ease your fever and sore throat. You'll need emergency care right away for severe symptoms, such as confusion, seizures, and muscle weakness, to prevent brain damage and other complications.

You can get shots to prevent Japanese encephalitis before you travel to the area.

Zika Virus

First found in Africa in the 1940s, this virus has spread to South and Central America, Mexico, the Caribbean, Southeast Asia, and the Pacific Islands.

Most people don't know they have Zika. The symptoms are mild and usually run their course in less than a week. You may have a fever, joint or muscle pain, pinkeye, or a rash.

The virus has been linked to more serious problems: cases of Guillain-Barre syndrome and a birth defect called microcephaly.

Guillain-Barre is a nervous system disorder that can cause weakness and paralysis. Most people recover over time.

Microcephaly causes a baby's head to be small and not fully develop. Babies with this condition may have developmental and intellectual delays and other problems.

There's no vaccine to prevent the virus. The CDC recommends pregnant women avoid traveling to areas with ongoing Zika infections.

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Chikungunya Virus

Found mostly in the Caribbean and South America, chikungunya is now spreading in the U.S. It causes severe pain in your joints that may last several weeks. You'll need rest and fluids until symptoms go away. Your doctor may suggest pain relief medicine, too.

Dengue Fever

You'll likely get a sudden high fever and may bleed a little from your nose or gums. It can be very uncomfortable. Rest and treating the symptoms are the only things you can do for dengue.

Some people get a more severe form, known as dengue hemorrhagic fever. If your small blood vessels become leaky and fluid starts to build up in your belly and lungs, you'll need medical care right away.

Usually people in the U.S. with dengue bring it back with them from warm parts of Africa, Asia, Pacific Islands, Central and South America, and the Caribbean -- especially Puerto Rico. In the last 20 years, though, there have been outbreaks in South Texas, Hawaii, and the Florida Keys.

Yellow Fever

You're not likely to catch yellow fever, because most countries in tropical areas of Africa and the Americas require travelers to get the vaccine for it. Most people that get yellow fever won't notice anything, but some may feel like they have a mild case of the flu. If you get symptoms, you can relieve them with rest, fluids, and medication, although you could feel weak and tired for several months.

About 15% of people who have mild symptoms will develop severe symptoms after they start feeling better, including a high fever, jaundice (your skin and the whites of your eyes turn yellow), and bleeding. The disease can make your liver and kidneys fail, and it could be fatal.

Malaria

The oldest mosquito bite illness causes more than 600,000 deaths worldwide each year. No one has gotten sick from malaria parasites in the U.S. since the early 1950s. But small outbreaks have happened when people who got infected in warm, wet parts of the world came back to the U.S. Countries around the equator in Africa and tropical islands in the Pacific, such as Papua New Guinea, have the most cases of malaria.

You can take drugs to help prevent malaria when you travel. Researchers are working on a vaccine.

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Battle the Bite

Many mosquitoes live for 2 to 3 months. Most will die or hibernate when the temperature drops below 50 degrees. In the U.S., mosquito season begins in early spring, peaks in the summer, and ends with the first freeze. In parts of the world with warmer weather, they may be active year-round.

The best way to prevent the illnesses they spread is to avoid mosquito bites.

  • Wear light-colored clothing to cover up.
  • Put mosquito repellent "bug spray" on your bare skin.
  • Get rid of places that water can collect around your home.
  • Keep water in pools and landscaping moving.
  • Use screens on your windows or a mosquito net when sleeping outdoors.
WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on January 27, 2016

Sources

SOURCES:

State of Connecticut, Mosquito Management Program: "Mosquitos: Frequently Asked Questions."

American Mosquito Control Association: "Mosquito-Borne Diseases."

CDC: "West Nile Virus," "Eastern Equine Encephalitis," "Japanese Encephalitis," "Chikungunya virus," "Dengue Homepage," "Yellow Fever," "Malaria," "Zika Virus," "Morbidity and Mortality Weekly Report," "Guillain-Barre syndrome and flu vaccine," "Facts about Microcephaly."

Wisconsin Division of Public Health: "West Nile Virus Infection."

Pal, P. Journal of Virology, published online May 14, 2014.

Pan American Health Organization: "Zika virus infection and Zika fever: Frequently asked questions."

National Institute of Neurological Disorders and Stroke: "Guillain-Barre Syndrome Fact Sheet."

The Atlantic: "What to Know About Zika Virus."

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