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Mosquito-borne diseases: What to know

A guide to keeping yourself safe from infections spread by the pesky insects
The best way to avoid these diseases is through prevention

Oh, the great outdoors! They provide the most memorable days at the lake, waterpark rides or camping trips—perfect for summer vacation. However, getting in touch with the great outdoors can lead to problems from unwanted guests if you’re not careful. An expert from the Texas A&M College of Medicine talks about a few of the more common illnesses brought about by mosquitos and how to keep their pesky bites at bay.

West Nile

The West Nile virus is a virus that can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord) and can even be fatal in severe cases. The virus has been detected in 48 states, and cases have occurred every summer since 1999, when it first made an appearance in the United States.

“West Nile is endemic in Texas,” said Cristie Columbus, MD, vice dean at the Texas A&M College of Medicine in Dallas and an infectious disease specialist. “Every year, Texas will have cases of West Nile virus during the warmer times of the year.”

The West Nile virus has already been spotted in mosquito samples around Texas, and although serious West Nile disease is rare, it can be devastating. Most people infected by the virus will present without symptoms, and a few will present with mild symptoms (fever, headache, body ache, rash and/or swollen lymph nodes) and expect a complete recovery. However, a small fraction will have severe neurological symptoms that can be fatal.

There is no cure for West Nile, and those with severe symptoms need to be hospitalized to receive supportive treatment, such as IV fluids, pain medication and nursing care. West Nile virus is not contagious through normal person-to-person contact. In rare cases, the virus can be transmitted via blood transfusion, organ transplant, or from mother-to-baby during pregnancy, delivery and breastfeeding.


While Zika is no longer a global emergency, there are still confirmed cases popping up throughout the United States, and it doesn’t take much to cause an outbreak.

Most people who contract Zika are asymptomatic or only have very mild symptoms. Common symptoms of Zika include fever, skin rash, red eyes and joint pain. Some patients report muscle pain, general malaise, headache and vomiting. Symptoms typically last between two and seven days. Complications are rare, but some cases require hospitalization for supportive care.

“Zika is unique in that it is sexually transmittable and can present a serious risk for pregnant women or women looking to get pregnant,” Columbus said. “While there is a risk for anyone contracting Zika, pregnant women who contract Zika are at a greater risk for complications.”

Researchers think Zika is behind the rise in miscarriages and microcephaly in certain endemic areas.  Microcephaly is a birth defect in which the infant has an unusually small head and abnormal brain development. For everyone else, the biggest potential complication is Guillain-Barré syndrome, in which the immune system attacks the body’s own nerve cells, causing problems with muscle coordination and breathing.

Chikungunya and dengue

Chikungunya and dengue are both transmitted by the Aedes aegypti and Aedes albopictus species of mosquitos, the same mosquitoes that transmit Zika, and they can cause a variety of problems—especially since these types of mosquito can spread more than one disease.

Chikungunya causes fever and severe joint pain, and although it is not often fatal, the symptoms can be severe and disabling.

Dengue presents with high fever, severe pain behind the eyes, muscle and joint pain, rash and mild bleeding (nose, gums or easy bruising). Dengue hemorrhagic fever will have a fever that lasts up to a week, and as the fever declines, other symptoms, such as abdominal pain or vomiting will begin. During thing time, the body’s circulatory system is compromised, and emergency intervention is necessary to decrease the chance of death.

Although Chikungunya hasn’t been spotted in the continental United States this year, it’s a growing concern. Recent studies have found that the mosquito vectors are more common than previously thought, and the optimal temperature for these mosquitos to spread disease is 84 degrees Fahrenheit.

“The warmer climate is more hospitable to mosquitos,” Columbus said. “Especially if they are able to survive a mild winter, then you can expect more mosquitos during the peak mosquito seasons and further inland.”

Protecting yourself

Because there is no cure for any of these diseases, the best way to protect yourself is to avoid mosquito bites. You can protect yourself from mosquitos by wearing insect repellent with 25 percent DEET and wearing long, and lightweight, clothing that covers up your skin.

“In Texas, the main mosquito vector that carries West Nile virus is the Culex species, and its habits are different from the ones that carry Zika or dengue,” Columbus said. “Culex mosquitos are most active at night, particularly at dusk and dawn, whereas Aedes species are more active during the day. You want to be protected throughout the day and night.”

You also want to do your part for your home and the community. “Be sure to put screens without any holes or tears over doors and windows, and remove standing water around your home—like in ditches, flower pots, bird baths,” Columbus said. “It’s also important to report dead birds. West Nile virus can infect many bird species, but is more likely to be fatal in crows, blue jays and ravens, so if you see any, depending on your community, experts can see if they were infected by West Nile virus.”

Talk to your health care provider

Mosquitos are so common that it seems odd to address concerns about mosquito-borne diseases, however, you should contact your health care provider, especially if you are pregnant, to discuss what should be done.

“You should always address your concerns with your health care provider,” Columbus said. “If you plan on traveling to certain locations, ask your health care provider about precautions that should be taken or the necessity of postponing your travel to a later date.”

Travel notices can be found on the website for the Centers for Disease Control and Prevention (CDC) here.

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