If travels to Southeast Asia, Africa, or even Florida are in your immediate future, take the time to prepare yourself against mosquito-borne illnesses. Mosquitoes thrive in warm climates, and some may carry viruses that can be passed to humans through their bites. Here is a rundown of mosquito-borne diseases you should be aware of when planning your next trip.


Several mosquito-borne diseases can cause a severe condition called encephalitis, which is an inflammation of the brain. An infected person may first experience flu-like symptoms, such as headache, fever, nausea, vomiting, and fatigue. In some cases, there may not be any symptoms.

If the condition worsens, it can lead to nerve damage, coma, seizures, long-term disability, and death. For most forms of encephalitis, there is no treatment. Care is given to ease symptoms.

Below are some forms of mosquito-borne encephalitis:

ConditionCases Reported in…Mosquitoes Transfer the Virus to Humans From…
Japanese encephalitisRural areas of AsiaInfected pigs and birds
St. Louis encephalitisMost cases in Eastern and Central United States, but virus found in all lower 48 states Infected birds
–Severe cases usually seen in older adults.
La Crosse encephalitisUpper Midwest, Mid-Atlantic, and Southeastern United States Infected small mammals, such as squirrels
–Severe cases usually seen in children 16 years old and younger.
Eastern equine encephalitis (EEE) Southeastern and Eastern United StatesInfected animals, such as horses
Western equine encephalitisWestern and Central United StatesInfected animals such as horses
Venezuelan equine encephalitisCentral and South AmericaInfected animals such as horses

West Nile Virus

West Nile virus has been reported in Africa, Asia, the Middle East, Europe, and the United States. Mosquitoes spread the virus to humans from feeding on infected birds. Symptoms are similar to the flu.

Symptoms may progress to memory loss, difficulty walking, or muscle weakness. There is no treatment for West Nile virus. Care is given to ease symptoms.

Dengue Fever

Several viruses carried by the Aedes aegypti mosquito cause dengue fever. Dengue fever is commonly reported in tropical urban areas in Asia, South America, Central America, North America, Africa, as well as the South Pacific and Caribbean. Fever is the main symptom, along with at least 2 of the following:

  • Headache
  • Pain in the back of the eyes
  • Nausea
  • Vomiting
  • Muscle or joint pain
  • Flushed face
  • Rash
  • Sudden bleeding

A more severe form of the disease can cause:

  • Massive blood loss through bleeding
  • Shock
  • Organ damage

Symptoms are treated with rest, fluids, and pain medications.

Yellow Fever

Yellow fever occurs in tropical cities, towns, and villages of Africa and South America. It spreads from an infected human to other humans by the Aedes aegypti mosquito. Symptoms include:

  • Fever
  • Chills
  • Headache
  • Muscle aches
  • Backache
  • Vomiting

Symptoms can progress to:

Treatment includes rest, fluids, and pain medications.

Rift Valley Fever

Rift valley fever is a condition found in parts of eastern and southern Africa where cattle and sheep are raised. The condition has also been reported in sub-Saharan Africa and the Middle East. It most often occurs after heavy rainfall or flooding. Humans contract the virus from a mosquito that has fed on an infected animal. Symptoms include:

  • Fever
  • Weakness
  • Back pain
  • Backache
  • Extreme weight loss

More severe symptoms include:

  • Fever with shock or hemorrhage
  • Eye diseases
  • Inflammation of the brain

There is no standard treatment. Recovery usually takes a few days to a week.


Unlike other mosquito-borne diseases, malaria is caused by a parasite, not a virus. Malaria has been reported in Africa, Asia, and Latin America. The disease is spread by the Anopheles mosquito. Symptoms are similar to the flu.

Severe symptoms may include:

Antimalarial drugs are used to treat malaria by killing the parasite.

Ways to Protect Yourself

Visit the Centers for Disease Control and Prevention Travelers’ Health website for updates on travelers' health concerns in various countries. Also, visit a travelers' health clinic or talk with your doctor to find out if vaccinations or other preventive measures are required before travel.

Two common methods of protection are the yellow fever vaccine and antimalarial medications. Antimalarial medications can be prescribed at a travel clinic or by your doctor and must be started up to 2 weeks before your trip. They are also taken during and after your trip. Yellow fever vaccination is usually available only at a travel clinic and has to be completed 10-14 days prior to travel to be effective. Be sure to plan ahead to get these before you travel.

When you are at your destination, take the following steps:

  • Avoid or limit outdoor activity during peak exposure times. Mosquitoes are active and biting at all times. They are especially active at dawn, dusk, and in the evenings.
  • Avoid areas where there are outbreaks. Be aware of areas where outbreaks are common. Avoid travelling to places where there are active epidemics. If you have to travel to these areas, make sure you are prepared in case of exposure. Updates are available on the CDC travel webpage.
  • Stay out of vegetated areas and grassy areas.
  • Apply repellent to exposed skin. Look for active ingredients, like DEET or picaridin, which provide long-lasting protection against mosquitoes and other insects. Other types of repellents include EPA-registered products that have oil of lemon eucalyptus, PMD (the man-made version of oil of lemon eucalyptus), or IR3535.
  • Wear protective clothing. Keep mosquitoes from making contact with your skin by wearing long-sleeved shirts that are tucked into your long pants, socks, boots or other closed shoes, and a hat.
  • Wear repellent on your clothing. Add an extra layer of protection to your clothes, shoes, and gear by applying repellents or insecticides (like permethrin). Re-apply after washing clothes.
  • Check the screens on the doors and windows. Look for small holes and gaps in the screens. If you notice any problems, repair them yourself or ask someone to help you.
  • Put up a net. Your sleeping area should have screens or be air-conditioned. If not, put up nets around your bed. The nets should reach the floor. If they do not, tuck the ends into your mattress. Spray the net with repellent or insecticide. Pretreated nets are also available.
  • Remove stagnant water. Mosquitoes lay their eggs in stagnant water. That's why it is so important to get rid of water that has collected around the property. Even small containers, like jars and cans, can be a breeding ground for mosquitoes.