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12 Mosquito-Borne Diseases You Need to Know About ASAP

Before you barbecue and swim this summer, take steps to protect yourself and your family against mosquito-borne diseases. Here's what you need to know.


Zika and beyond

Mosquito season is upon us, folks. These pesky critters can do more than bother everyone at your upcoming barbecue, though. Some mosquitoes carry diseases that can be dangerous to some people. Zika may be one of the most-discussed, but it's certainly not the only one to pose a threat to people who want to enjoy the outdoors this summer. Here's how to avoid the skeeters that carry Zika and just about every other fact you'll need about the disease, but in general it's the bug spray-and-coverup time of year.


West Nile virus

You've no doubt heard of this one: West Nile virus is one of the most-feared mosquito-borne diseases, but most people infected have no symptoms, and therefore don't even realize they have it—which means you have nothing to worry about. The CDC states that only 1% of those infected can develop a serious or fatal neurological disorder. However, there have been outbreaks in recent years, even in the United States. According to Brad Leahy of B.O.G. Pest Control, the most common areas to find West Nile outbreaks are those that follow bird migration patterns since mosquitoes that feed on birds infected with the virus are its carriers. So far, West Nile virus has made its way to every state, except for Hawaii and Alaska.

West Nile virus tends to behave like a case of the flu, causing headaches, body aches, fatigue, joint pain, diarrhea, vomiting, and sometimes a rash. Signs that it could be heading to a more severe form include high fever, stiffness, seizures, coma, or paralysis in any part of the body. There is no vaccine available for West Nile, and severe cases require hospitalization.

To protect yourself against mosquitoes potentially carrying West Nile virus, keep your skin protected, wear mosquito repellant spray, and consider eating foods that defend against mosquito bites before you head outside.


Dengue virus

According to Leahy, yellow fever mosquitoes, which are responsible for Zika, Chikungunya, and—yes—yellow fever, can also transmit dengue virus. Commonly found in tropical climates, dengue in the United States is mostly a threat along the southern border.

The CDC lists common symptoms of dengue virus as rash, muscle, joint, or bone pain, severe headache, eye pain, and mild bleeding from the nose or gums. More severe symptoms include vomiting blood, cold or clammy skin, black or tarry stools, and severe abdominal pain. Extreme cases can lead to circulatory failure and death. There's currently no treatment for the disease, but most people can lower the severity of symptoms with pain-relieving drugs and drinking plenty of water to stay hydrated.

The best prevention for dengue virus, like other mosquito borne diseases, is avoiding mosquito bites, especially if you're already feeling ill or have a fever. Take this list of things mosquitoes absolutely hate on your next camping trip or outdoor adventure.


Western equine encephalitis

Typically transmitted by Culex mosquitoes—the type you usually see buzzing around your backyard—Western equine encephalitis (WEE) concentrates west of the Mississippi River in the United States. Its name comes from its presence in horses. It's extremely rare, with only about 700 cases confirmed in the United States since 1964.

The mortality rate for WEE is low, and the elderly population is most at risk for severe, or fatal, symptoms. Most people develop flu-like symptoms, like nausea, vomiting, headache, and body aches. Unfortunately, there's only a vaccine available for horses, so humans should avoid the outdoors at dusk and dawn when these mosquitoes are most active.



This African virus has hit the international scene thanks to the spread and hardiness of the Asian tiger mosquito (yellow fever skeeters can also carry the virus).  Although the virus is very rare in the United States, travelers from the most affected areas, like Africa, India, and Asia, can transport it.

The virus mirrors many of the same symptoms as dengue and Zika, including headaches, body aches, muscle and joint pain, and fever which usually turn up between three and seven days of a bite. The groups at highest risk for severe complications are the elderly and newborns—but severe reaction is rare.

There's no vaccine to protect against chikungunya, so investing in a protective insect repellent before traveling or spending time outdoors is especially important. Leahy recommends a repellent with DEET, IR3535, oil of lemon eucalyptus, or picaridin for the best protection. To cut down your exposure, try landscaping with some of these  mosquito-repelling plants.


Yellow fever

Bringing us yellow fever is the aptly named yellow fever mosquito, but tiger mosquitoes also carry the virus found mostly in tropical areas of Africa and South America. Yellow fever is rarely transferred to the United States via travelers, thanks to a live-virus vaccine given to people pre-travel, however a particularly severe outbreak in Brazil has US public health officials watching for cases in Puerto Rico and Gulf Coast states.

Early onset symptoms of yellow fever occur about three days after a bite; they include headache, body aches, nausea, vomiting, and fever. According to the CDC, about 15 percent of cases seem like they're getting better before turning serious with a high fever, jaundice, and body organ failures. The severe form has up to a 50 percent mortality rate.


Lymphatic filariasis

One of the lesser-known mosquito-borne diseases, lymphatic filariasis also is one of the most dangerous. The infection is caused by a parasitic worm transferred by several types of mosquitoes and is found in several countries in Africa, South America, and the Western Pacific. It doesn't commonly transfer to the United States from travelers.

The parasite can cause extreme swelling in the arms, legs, or genitalia. Hardening of the skin, known as elephantiasis, may also occur. A drug known as DEC can kill the infection and the parasites that cause it when used for its full 12-day regimen.

Since the types of mosquitoes that transmit lymphatic filariasis are numerous, it's important to protect yourself if you're traveling to an infected area. If you're outside between dawn and dusk, Leahy suggests using a "mosquito net that has been treated with insecticide will shield you from bites, especially at dusk, when mosquitoes are most active." This disease is yet another reason to know all the ways you can avoid mosquito bites.


Japanese encephalitis

Japanese encephalitis is transmitted to humans through Culex mosquitoes in Asia and the Western Pacific. An infection can cause fever, headache, and vomiting, and very rare cases lead to neurological symptoms and seizures.

According to Leahy, the risk of humans contracting the virus, even when traveling to affected areas, is low. "The Culex mosquitoes which carry this disease breed in agricultural zones and flooded rice fields and are more likely to bite at night," he says. Your best bet at prevention is to stay indoors at night and use mosquito netting.


St. Louis encephalitis

St. Louis encephalitis is transferred to humans from Culex mosquitoes. It concentrates mainly within the United States and has made an appearance in several central and eastern states. According to the CDC, about 99% of cases go undiagnosed because they resolve with no symptoms. However, there's a higher risk of serious complications in older adults than in children. Common symptoms include fever, dizziness, and nausea, and can go from mild to severe rapidly. Severe cases can result in coma, and the elderly population is especially at risk of developing encephalitis, or brain inflammation.

There's no vaccine or treatment available for this virus. Although the number of cases in the United States has dwindled in recent years, it still exists, so be mindful of active mosquito periods in your area and protect yourself.


La Crosse encephalitis

LCEV, as it's known, spreads in bites from treehole mosquitoes. Unfamiliar with that breed? You probably don't live in the southern, upper Midwest, or mid-Atlantic states where the mosquitoes are prevalent and most of LCEV cases cluster. Usually, LCEV goes unnoticed, with extremely mild or no symptoms, but it can be dangerous to children under 16 years old.

Fever, vomiting, and fatigue are the most common symptoms; seizures can accompany even mild forms of the virus. In extremely rare cases, neurological symptoms can cause long-term paralysis or disability, and can sometimes be fatal. No vaccine or treatments for LCEV exist, so it's important to keep yourself and your yard protected. You won't be surprised to hear that the mosquitoes typically lay eggs in treeholes, so prevent breeding by filling treeholes with soil.


Eastern equine encephalitis

Eastern equine encephalitis (EEE) is "one of the most severe mosquito-transmitted diseases in the United States, though most people don't know about it," says Leahy. "Almost one-third of people infected with Eastern equine encephalitis die, and many survivors face varying levels of brain damage," says Leahy. Florida, New Jersey, and Georgia have seen the highest number of EEE cases, but states near the Great Lakes are close behind.

Culiseta melanura mosquitoes are responsible for this virus, which has no vaccine or treatment. Symptoms can be systemic, with chills, fever, and body aches, or encephalitic, with vomiting, convulsions, and coma. Since these mosquitoes especially love a good water breeding ground, make sure any standing water in your yard is emptied promptly to avoid them taking over. And while you're preventing and treating your mosquito bites, have this list of bug bite treatment dos and don'ts handy.


Venezuelan equine encephalitis

Closely related to EEE, this one is thankfully not as common in the United States—yet, warns Leahy. He says that it's possible the mosquitoes that transmit the virus could make their way from South and Central America to the southern border of the United States.

VEE carries many of the same symptoms as EEE, but may also pose a high risk to the fetuses of pregnant women, resulting in miscarriage. Most people feel relief from symptoms within five days of onset, but in rare cases, the virus can be fatal.


While mosquito season is in full swing, it's still important that you pay attention to other types of bug bites you notice. Check out this list of bug bites you should never ignore to prevent any dangerous symptoms and diseases.