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What Diseases Do Mosquitoes Spread & Transmit?

Mosquitoes are known for the diseases they’ve spread worldwide. Each year, there are more than 700,000 deaths from vector-borne diseases. These diseases have disproportionately affected populations in tropical and subtropical regions, but are a global threat. Learn more about how mosquitoes spread diseases, the most prevalent species in our region, and the steps you can take to help protect you and your family.


Which Mosquitoes Can Transmit Disease?

The three species of mosquitoes that are responsible for spreading diseases are Aedes, Culex, and Anopheles mosquitoes. There are multiple species within these families. Thankfully, there are many types of mosquitoes that are not responsible for transmitting disease and are primarily a nuisance pest. Here in North Carolina, we have had reported cases of the Aedes mosquito.

Mosquito extreme close up

Common Mosquito-Borne Diseases in the U.S.

More than 200 types of mosquitoes are found in our nation. Of those, only about 12 types are capable of transmitting disease. The diseases that have been found in the United States include Dengue, chikungunya, Zika virus, and Malaria; these outbreaks occurred in North Carolina, Texas, Puerto Rico, Hawaii, and the US Virgin Islands. Most cases of malaria reported occur in returned travelers from tropical regions. Most types of mosquitoes we encounter are nuisance mosquitoes that are incapable of transmitting the diseases that make people sick. Here are the most common ones that affect residents:

Eastern Equine Encephalitis (EEE)

A serious disease spread by mosquitoes, primarily affecting the eastern U.S. Symptoms range from mild flu-like illness to severe encephalitis, which can be fatal or cause significant brain damage in survivors.

Saint Louis Encephalitis (SLE)

While many infected individuals in the central and eastern U.S. – experience no symptoms, some do develop fever, headache, dizziness, nausea, and fatigue. Severe cases can progress to encephalitis, leading to confusion, seizures, or coma.

La Crosse Encephalitis (LAC)

It is primarily transmitted by the Aedes triseriatus mosquito and mainly affects children in the upper Midwestern and Appalachian regions. Symptoms can include fever, headache, nausea, vomiting, fatigue, and neurological issues like seizures and encephalitis, which can be severe in some cases.

Less Common Mosquito-Borne Diseases in the U.S.

Western Equine Encephalitis – while less common, mosquito-borne diseases still pose risks to residents in the U.S.

Western Equine Encephalitis (WEE)

Western Equine Encephalitis (WEE) is a rare mosquito-borne virus primarily found in the western United States. Transmitted by Culex tarsalis mosquitoes, WEE can affect both humans and horses. Symptoms in humans range from mild flu-like illness to severe neurological conditions such as encephalitis, which can result in brain damage or death, particularly in infants and the elderly. While human cases are infrequent, the disease remains a concern due to its potential severity.

Mosquito-Borne Diseases Affecting U.S. Travelers

U.S. travelers to certain regions face the risk of contracting various mosquito-borne diseases. Here are some of the notable diseases that can affect Americans abroad.


In the tropical and subtropical regions – travelers infected with chikungunya often experience sudden onset of fever and severe joint pain, headaches, muscle pain, joint swelling, and rash. While rarely fatal, the joint pain can be debilitating and persist for months.


Dengue is common in many parts of Asia, the Pacific, the Americas, Africa, and the Caribbean. Symptoms include high fever, severe headache, pain behind the eyes, joint and muscle pain, rash, and mild bleeding. Severe cases can lead to dengue hemorrhagic fever or dengue shock syndrome, both of which can be fatal without proper medical care.

Zika Virus

Reported in tropical and subtropical areas around the world. The effects are mild symptoms like fever, rash, conjunctivitis, muscle and joint pain, and headache. However, Zika is particularly dangerous for pregnant women, as it can cause severe birth defects such as microcephaly in babies.

Japanese Encephalitis

Spread by Culex mosquitoes, primarily found in rural parts of Asia. The result of mild symptoms, but severe cases can lead to encephalitis, characterized by high fever, headache, neck stiffness, disorientation, coma, seizures, and paralysis. The disease has a high mortality rate and can cause permanent neurological damage in survivors. 

How Do Mosquitoes Spread Disease?

Mosquitoes spread disease by biting an infected person or animal and biting another host. When they bite, they inject saliva containing viruses or parasites into the new host’s bloodstream, transmitting the disease. This process makes mosquitoes effective carriers of various illnesses.

Symptoms Of Mosquito-Borne Disease

If you are bitten by a mosquito in North Carolina, you most likely will get few symptoms and recover and just a few days. So what symptoms alert you that you may be suffering from something more serious? If you notice any of the following symptoms after being bitten by a mosquito, it’s time to seek professional medical help:

  • Sudden high fever
  • Stiff neck
  • Confusion
  • Nausea or vomiting
  • Muscle tremors or seizures
  • Severe headaches
  • Rash

Steps To Reduce The Risk of Mosquito-Borne Infections

  1. Insect Repellent: Apply repellents containing DEET, picaridin, or oil of lemon eucalyptus to exposed skin and clothing.
  2. Protective Clothing: Wear long-sleeved shirts, long pants, socks, and shoes to reduce skin exposure.
  3. Mosquito Nets: Sleep under insecticide-treated mosquito nets, especially in areas with prevalent mosquito-borne diseases.
  4. Screens: Ensure windows and doors are fitted with screens to keep mosquitoes out of living spaces.
  5. Standing Water: Remove or treat standing water in items like birdbaths, flowerpots, and gutters to reduce mosquito breeding sites.
  6. Peak Times: Avoid outdoor activities during dawn and dusk when mosquitoes are most active.
  7. Air Conditioning: Mosquitoes are less likely to enter cool, air-conditioned spaces.
  8. Be Aware of Travel Risks: Research mosquito-borne diseases in travel destinations and take appropriate precautions, including vaccinations if available.

See our guide for more information if you have been bitten and need a remedy. You can also learn more about what attracts mosquitoes to help arm yourself with the knowledge you need to protect yourself and reduce the risk of being bitten. 


The most common disease transmitted by mosquitoes is malaria. It is caused by Plasmodium parasites and is primarily spread by Anopheles mosquitoes. It affects millions of people worldwide, particularly in tropical and subtropical regions, and can lead to severe illness if not treated promptly—seek medical advice immediately.

On other mosquito diseases see our guide for more information

No, mosquitoes do not carry Lyme disease. Lyme disease is primarily transmitted to humans through the bite of infected black-legged ticks (also known as deer ticks) that are infected with the bacterium Borrelia burgdorferi. Mosquitoes do not play a significant role in the transmission of Lyme disease.

The likelihood of contracting a disease from a mosquito bite varies depending on factors such as geographical location, mosquito species, and individual behaviors. While millions of people worldwide are affected by mosquito-borne diseases annually, the risk of infection can be reduced through preventive measures such as insect repellents, protective clothing, and eliminating mosquito breeding sites.

What Attracts Mosquitoes & Draws Them To Humans? Serving Charlotte, Raleigh, Greensboro, and Durham

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