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General Health Infectious Disease Jun 23, 2023

Preventing Mosquito-Borne Illnesses

How to protect yourself and your loved ones amid reports of West Nile virus and malaria in Texas

Reviewed by: Elizabeth Douglass, MD
Written by: Lauren Schneider

A man spraying insect repellent onto his arm.

Update: This piece was edited on October 4, 2023, to reflect more recent information from the City of Austin and surrounding communities regarding West Nile virus.

On June 23, 2023, the Texas Department of State Health Services (DSHS) announced that a Texas resident who had not traveled outside the country or state had been diagnosed with malaria, a serious disease caused by a parasite that is transmitted through mosquito bites. Along with seven other cases identified in Florida this summer, this marks the nation’s first instance of malaria since 2003 that is unrelated to travel in regions where the condition is endemic.

Weeks after the malaria case was identified in Texas, Dallas County Health and Human Services reported the state’s first human case of West Nile virus this year. While still rare, West Nile virus is the most common cause of mosquito-borne illnesses in the continental United States, with the state of Texas counting 42 cases and 7 deaths associated with the virus in 2022.

Austin’s first case of West Nile virus in 2023 was confirmed by Austin Public Health on September 29 after a Travis County resident died from the disease. The previous month, the first local human case in the greater Austin area was reported in Williamson County.

“We are definitely seeing an uptick in mosquito-borne diseases,” warns Elizabeth Douglass, MD, a board-certified infectious disease specialist in UT Health Austin’s Infectious Disease Clinic. “There is a concern that as the climate is warming, mosquitoes that transmit certain infections are migrating to regions where these diseases were previously less common.”

Know the Signs

Mosquito-borne illnesses are a growing concern in the United States, but they are still relatively rare compared to other infectious diseases, and many people who contract these illnesses do not develop any symptoms. “For people bitten by mosquitos who start to feel ill, vigilant symptom monitoring is key,” says Dr. Douglass. “Neurological symptoms are an urgent sign to seek medical attention.”

Malaria

According to the Centers for Disease Control and Prevention (CDC), malaria symptoms can be classified as either uncomplicated (common and less severe) or severe (more severe and potentially life-threatening). Some variation in malaria symptoms is due to the multiple parasites that cause the disease. The species of parasite infecting a patient will also determine the course of antibiotic treatment required.

Symptoms of uncomplicated malaria may include:

  • Fever
  • Body aches
  • Chills
  • Fatigue
  • Headache
  • Nausea
  • Sweating
  • Vomiting

Symptoms of severe malaria may include:

  • Acute respiratory distress syndrome (ARDS)
  • Kidney damage
  • Neurologic symptoms (e.g., abnormal behavior, loss of consciousness or coma, seizures)
  • Blood and circulatory abnormalities (e.g., destruction of red blood cells leading to anemia and/or the presence of hemoglobin in the urine, excessive blood acidity, hyperparasitemia (more than 5% of red blood cells infected by parasites), low blood pressure)

West Nile Virus

The CDC estimates that 8 in 10 people who contract West Nile virus do not experience any symptoms. Most people who do develop symptoms (1 out of every 5 people infected with the virus) recover completely in a matter of weeks.

Common symptoms of West Nile virus may include:

  • Fever
  • Diarrhea
  • Headache
  • Muscle or joint pain
  • Rashes
  • Vomiting

In rare cases (1 in 150 people who contract West Nile virus), symptoms associated with infections are more severe as the virus infects the tissue of the brain and/or spinal cord.

Serious symptoms of West Nile virus may include:

  • Coma
  • Convulsions or tremors
  • Disorientation or stupor
  • Muscle weakness
  • Neck stiffness
  • Paralysis

“Unlike malaria, there is no established course of treatment for severe West Nile virus,” notes Dr. Douglass. “Patients with the virus usually receive supportive care.”

Understand the Risks

Because the symptoms associated with severe mosquito-borne disease can be life-changing or deadly, it is crucial to know who is at risk for more serious illness if infected. “Young children and pregnant patients are at very high risk for severe cases of malaria and West Nile virus,” cautions Dr. Douglass.

Additional risk factors for severe West Nile virus include:

  • Age: Individuals over the age of 60 are more likely to become seriously ill if infected.
  • Health history: Individuals with a history of cancer, chemotherapy treatment, transplant surgery, cirrhosis or severe alcohol use disorder are at greater risk for severe West Nile virus.

In addition to being at risk for more severe illness, pregnant people must take extra precaution to avoid mosquito-borne conditions because their infection can be passed through the bloodstream to their fetus.

Prevent Mosquito Bites

Other than maternal-fetal transmission and exceedingly rare cases acquired through blood transfusion, mosquito-borne illnesses are transmitted only through mosquito bites and cannot be passed from person to person. “Protecting yourself from mosquitoes is your first line of defense against these illnesses,” explains Dr. Douglass. “These precautions are especially important during dusk hours when mosquitoes are most active and can also help you avoid those pesky, itchy bites from mosquitoes that do not carry disease.”

Protect Your Skin

“The main way to defend yourself against mosquito bites is to cover your skin,” says Dr. Douglass. “Your arms, legs, and even hands should ideally be covered in fabric, and tucking your shirt in provides extra protection. If you are outdoors a lot, you may consider a mosquito net.”

In addition to the physical barrier provided by clothing, insect repellent can help deter mosquito bites. Environmental Protection Agency (EPA) offers a search tool to help you find a safe, effective mosquito repellent that suits your individual preferences.

Avoid Standing Water

Another strategy for preventing mosquito bites is to stop the spread of mosquitoes themselves. “One way to limit the mosquito population is to get rid of your reservoirs of standing water where mosquitoes can lay their eggs,” advises Dr. Douglass. “If you have a water feature in your yard, make sure the water is moving and chlorinated.”

Stay Informed

“While diseases like malaria and West Nile virus are still rare in the United States, people can protect their health by educating themselves about these conditions,” says Dr. Douglass. A myriad of resources about mosquito-borne illnesses at the local, state, and national level can help keep you safe this summer.

All Mosquito-Borne Illnesses

Malaria

    West Nile Virus

    General Health Infectious Disease

    About UT Health Austin

    UT Health Austin is the clinical practice of the Dell Medical School at The University of Texas at Austin. We collaborate with our colleagues at the Dell Medical School and The University of Texas at Austin to utilize the latest research, diagnostic, and treatment techniques, allowing us to provide patients with an unparalleled quality of care. Our experienced healthcare professionals deliver personalized, whole-person care of uncompromising quality and treat each patient as an individual with unique circumstances, priorities, and beliefs. Working directly with you, your care team creates an individualized care plan to help you reach the goals that matter most to you — in the care room and beyond. For more information, call us at 1-833-UT-CARES or request an appointment here.