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Mosquitoes The Annoying Insects that can Spread Disease

The Bottom Line

The majority of mosquito bites only cause minor skin irritation. However, mosquitoes can spread serious viral, bacterial, and parasitic infections. The most effective way to prevent infections spread by mosquitoes is to prevent mosquito bites.

The Full Story

Mosquitoes are pesky insects that can bite and leave your skin with red, itchy bumps. They are the reason why you might not enjoy a summer day at the pool or an evening walk in the park. What makes mosquitoes very important to humans is not just their annoyance but also their ability to spread disease. Mosquitoes are important vectors of disease. Vectors are organisms that transmit bacteria, viruses, and parasites from one infected person or animal to another. Other common vectors include ticks and fleas.

Worldwide, the most important disease spread by mosquitoes is malaria, which infects 2 million people every year and kills 500,000. While the majority of the diseases transmitted by mosquitoes occur in developing countries and in tropical and sub-tropical regions, infection and disease spread can be just a plane ride away or just around the corner. For example, the first case of West Nile Virus (WNV) in the US was identified in New York in 1999 apparently resulting from the arrival of an infected bird, human traveler, or mosquito. The virus has since spread rapidly and has infected about 40,000 people in the US. Of these, 17,000 became very ill and about 1600 died. Mosquitoes are also responsible for the spread of heartworm disease in pets.

Only female mosquitoes bite, because they need a blood meal to make eggs. Male mosquitoes feed only on nectar. Mosquitoes are experts at finding humans and animals to bite by sensing movement, color, temperature, moisture, and chemicals like carbon dioxide, which we release during normal breathing. This means we have to use several techniques to beat them at their game.

Fortunately, the majority of mosquito bites do not lead to disease. Even so, the best way to prevent infection is to prevent a bite. Here are important preventive tips:

  • Limit mosquito breeding grounds. Mosquitoes breed in standing water; homeowners should remove sources of standing water (areas where water can collect after rainfall) around their home. A few examples are flowerpots, buckets, pet dishes, discarded tires, and birdbaths. If you have a swimming pool, perform adequate maintenance to prevent mosquito breeding. Report abandoned swimming pools to your local health department.
  • Keep mosquitoes out of your home. Install and quickly repair screens on windows and cover gaps in doors and walls.
  • Reduce your risk of a bite:
    • Use insect repellents and be sure to follow label directions for safe use. Use repellents that have been registered by the Environmental Protection Agency (EPA). EPA-registered repellents have been approved for safety and effectiveness. 
    • Use your clothing as a barrier by wearing long sleeves, pants, socks, and shoes.
    • Limit your time outdoors when mosquitoes are the most active, which is between dusk and dawn.
    • Use mosquito netting to cover infant carriers when outdoors.

If bitten by a mosquito: Immediately disinfect the area by washing it with soap and water.

Itching will likely follow, and the bite site will be swollen, warm, and tender to touch. This is your body’s natural response to the mosquito’s saliva. Try your best not to scratch. Scratching will only result in more skin irritation. To relieve the itching, you can apply a nonprescription corticosteroid, like hydrocortisone 1% cream.

Watch the site for signs of infection. Increased pain, swelling, redness or warmth, or oozing of fluid from the site are signs that indicate wound infection. Also watch for symptoms of mosquito-transmitted illnesses, such as fevers, body aches, headaches or neck stiffness. Seek immediate medical evaluation and treatment if any of these symptoms occur.

Call Poison Control any time for treatment advice at 1-800-222-1222. A poison specialist will review what to do and symptoms to watch for. 

Serkalem Mekonnen, RN, BSN, MPH
Certified Specialist in Poison Information

For More Information

American Mosquito Control Association

Use DEET Safely, from The Poison Post®

Centers for Disease Control and Prevention, Division of Vector-Borne Diseases

Environmental Protection Agency (EPA), Insect Repellents

For Pet Owners:


American Mosquito Control Association (AMCA). Control [Internet]. Mount Laurel, NJ; 2014 [cited 2015 May 13]. 

Centers for Disease Control and Prevention (CDC). West Nile Virus: Prevention and Control [Internet]. Atlanta, GA; 2015 Feb 12 [updated 2015 Feb 12; cited 2015 May 13]. 

Hempelmann E, Krafts K. Bad air, amulets, and mosquitoes: 2,000 years of changing perspectives on malaria. Malar J. 2013;12:232.

Murray KO, Mertens E, Despres P. West Nile virus and its emergence in the United States of America. Vet Res. 2010;41:67.

World Health Organization (WHO). Malaria [Internet]. 2015 Apr [Updated 2015 Apr; cited 2015 May 30]. 

World Health Organization (WHO). Vector-borne Diseases [Internet]. 2014 Mar [Updated 2014 Mar; cited 2015 May 13]. 

World Health Organization (WHO). West Nile Virus [Internet]. 2001 Jul [Updated 2011; cited 2015 May 13]. 


CALL 1-800-222-1222

Prevention Tips

  • Control mosquitoes around your home by eliminating sources of standing water, which is where mosquitoes breed.
  • Use insect repellents and be sure to follow label directions for safe and effective use.
  • Use your clothing as a barrier by wearing long sleeves, pants, socks, and shoes.
  • Limit your time outdoors when mosquitoes are the most active, which is between dusk and dawn.
  • Use mosquito netting to cover infant carriers when outdoors.

This Really Happened

A father called Poison Control for advice 24 hours after his 4-year-old daughter had been bitten by a mosquito on her nose. The swelling had spread to below her eye. Poison Control advised the father to wash the bite daily, watch for signs of infection, and to take the child to her doctor if it got worse.

The father took the child to her pediatrician, who recommended an antihistamine and a corticosteroid to reduce itching. By the following day, the swelling had decreased, but her other eye was now swollen because she had been bitten there by another mosquito!