The West Nile virus is an illness spread by mosquitoes. Warm temperatures and high humidity present an ideal environment for mosquitos. This makes states like Texas and Florida prime states for mosquitos – and mosquito-borne illnesses like West Nile, Zika and malaria – to thrive.
Looking at the top five states for mosquitos, Texas leads the pack – followed by:
- California
- Florida
- Georgia
- New Jersey
There are currently 175 species of mosquitos in the United States. Florida is home to about 80 species, second only to Texas with 85.
Looking at the list of the top 50 cities for mosquitos – compiled by national exterminator Terminix – six Texas cities made the list. Dallas-Fort Worth had the second highest number of mosquitos in the U.S., second only to Los Angeles.
Other Texas cities and their ranking on the Top 50 list included:
- Houston No. 5
- San Antonio No. 14
- Tyler No. 25
- Austin No. 27
- Waco No. 38
Florida’s weather is similar to that in many parts of Texas, making it another popular mosquito breeding ground. Terminix ranked Orlando at No. 8 spot on the Top 50 list, followed by:
- Tampa-St. Pete No. 9
- Miami-Fort Lauderdale No. 13
- Jacksonville No. 26
- West Palm Beach No. 34
- Fort Myers No. 49
West Nile virus is the leading cause of mosquito-borne diseases in the U.S. – infecting birds, other mosquitoes, horses and other animals, as well as humans.
According to the U.S. Centers for Disease Control and Prevention (CDC), a total of 1,466 cases of West Nile were reported in the U.S. in 2024, down from 2,406 cases in 2023.
Unfortunately, both Texas and Florida are running counter to the national trend. In the Lone Star State, the CDC reported 92 cases of West Nile 2023. A year later, the number spiked to 176 cases. Meanwhile, Florida saw its number of West Nile cases rise from nine to 18 on a year-over-year basis.
Knowing how to spot and treat West Nile virus can help you and your family stay safe. Here’s what you need to know about this mosquito-borne illness.
How do people get West Nile virus?
Mosquito-borne diseases are blood-to-blood transferred. They are not contagious. Instead, humans contract West Nile virus by being bitten by an infected mosquito, and mosquitoes get the virus by feeding from infected birds.
West Nile virus may also spread in a medical lab, or during a blood transfusion or organ transplant. It may even spread from mother to baby during pregnancy, reports the CDC. However, these instances are very rare.
This virus cannot spread when you touch an infected live animal, such as a cow or bird, or by coughing or sneezing.
West Nile virus is usually only a year-round threat to those who live in southern climates, including Texas and Florida.
In many other parts of the U.S., West Nile is typically only a threat during the spring and summer months, when temperatures start to warm. These little pests can spread viral, bacterial or parasitic diseases to anyone, young and old, through their bites.
What are the symptoms of West Nile virus?
According to a recent article published by UT Southwestern Medical Center, West Nile virus causes no symptoms in 75% to 80% of people who get infected. The remaining 20% to 25% may experience what are known as West Nile fever symptoms. Symptoms usually show up within two to 14 days of being infected.
Common symptoms of West Nile virus include:
- Fever
- Headache
- Body aches
- Chills
- Fatigue
- Vomiting
- Rash
- Swollen lymph nodes
Older adults with a severe form of West Nile virus may experience additional symptoms which are often compared to the flu. These symptoms include:
- Neck stiffness
- Extreme weakness
- Confusion
- Vision loss
- Coma
- Tremors
- Convulsions
- Paralysis
In rare cases, West Nile virus may lead to serious, life-threatening problems. These complications include:
- Encephalitis (inflammation of the brain)
- Meningitis (inflammation of the lining of the brain and spinal cord)
- Meningoencephalitis (inflammation of the brain and its membrane)
Getting medical treatment early on may help prevent these and other issues.
Some people are more likely to get very sick from West Nile virus. This includes infants, young children, and adults over the age of 60. These populations may have weakened immune systems, making them more vulnerable to illnesses like the West Nile virus. Also increasing the risk of severe illness are chronic conditions such as:
- High blood pressure
- Chronic renal disease
- Hepatitis C infection
- Heart disease
Your provider can talk to you in more detail about your risk for West Nile based on your medical history.
How is West Nile virus diagnosed?
West Nile virus can be diagnosed using several different methods.
First, your doctor may discuss your symptoms and perform a physical exam. For example, a rash that develops on the trunk of your body may indicate West Nile.
Your doctor may also check to see if you have had a past mosquito-borne illness. In some instances, you may have a blood test to check for the presence of West Nile. Blood tests may also be done to confirm or rule out other conditions.
At present, there is no cure for West Nile virus. Mild symptoms may go away on their own within a few days without treatment. However, symptoms like fatigue or weakness can last for several weeks or months. Early detection of the disease can mean faster relief from your symptoms.
Malaria
West Nile may be the most common mosquito-borne illness in the U.S., but it is not the sole concern of health care organizations and those living in warm climates.
In June 2023, five locally acquired cases of malaria – one in Texas and four in Florida – made headlines when the CDC issued a Health Alert Network Health Advisory.
In an Emergency Preparedness and Response report, the CDC stated that in the U.S., about 2,000 people are diagnosed with malaria each year. The majority of cases stem from people who travel to areas where malaria transmission occurs. According to a World Health Organization report cited by TheCable, the top five countries carrying the heaviest burden of malaria cases in 2023 were Nigeria (26%), the Democratic Republic of the Congo (13%), Uganda (5%), Ethiopa (4%) and Mozambique (4%).
Individuals with malaria can suffer fever and flu-like symptoms, such as chills, headaches, muscle aches and fatigue. Nausea, vomiting and diarrhea may also occur. It is important that those exhibiting such symptoms see a health care provider immediately, as malaria can be deadly if left untreated.
The good news: Malaria can be cured with prescription drugs. And overall, the chance of being bitten by a mosquito carrying malaria is infinitesimal. According to the CDC, about one in 150 people infected with malaria develops a serious illness that may lead to death.
Can I prevent mosquito-borne illnesses?
Yes, preventing viruses or reducing your risk is possible.
The best method is to limit your exposure to mosquitoes. This is especially important if you meet risk factors for severe illness.
Other steps you can take:
- Stay indoors when mosquitoes are active. Peak hours for mosquitoes are at dawn, dusk, and in the early evening.
- Wear protective clothing. Thick, long-sleeved shirts and pants may prevent mosquitoes from biting the skin.
- Use EPA-registered insect repellent. These repellents may be sprayed directly on clothing or skin. Make sure you read the instructions and use only as directed.
- Drain sources of standing water. Mosquitoes like to breed in stagnant water, so empty sources of standing water around your yard and house, including in old tires, shoes, gardening equipment and flower pots. Change the water in bird baths, pet water bowls and children’s pools frequently.
- Repair or replace damaged screens or windows. This can help prevent mosquitoes from entering your home.
WellMed is dedicated to providing quality health care with a strong focus on prevention. Our lifestyle medicine doctors can test your family for West Nile virus and discuss available treatment options. Contact WellMed today at (888) 781-WELL or visit our website to find a doctor near you.
Resources
- (2025, April 18). Which cities have the most mosquitoes? https://www.terminix.com/mosquitoes/top-mosquito-cities/
- (2024, May 15). Transmission of West Nile Virus. https://www.cdc.gov/west-nile-virus/php/transmission/index.html
- UT Southwestern Medical Center. (2024, October 11). West Nile virus is on the rise: What Texans need to know. https://utswmed.org/medblog/west-nile-virus-texas/
- Florida Health. (2024, July 10). West Nile Virus (WNV). https://www.floridahealth.gov/diseases-and-conditions/west-nile-virus/
- (n.d.) Mosquito Prevention. https://www.austintexas.gov/department/mosquito-prevention
- Texas DSHS. (n.d.) Texas Counties with West Nile Virus Activity, 2024. https://www.dshs.texas.gov/sites/default/files/LIDS-Zoonosis/West%20Nile%20JPEG/2024/TX2024.jpg
- (2025, January 14). West Nile Virus Current Year Data (2024). https://www.cdc.gov/west-nile-virus/data-maps/current-year-data.html
- Neeley, S. (2023, August 17). 6 Florida counties rank high in U.S. for mosquito-borne diseases. Is your county on the list? https://www.news-press.com/story/news/2023/08/16/florida-counties-most-vulnerable-to-mosquito-borne-disease-malaria-dengue-west-nile-virus/70599425007/
- (2024, May 15). About West Nile. https://www.cdc.gov/west-nile-virus/about/index.html
- CDC (2023, August 28) Emergency Preparedness and Response, Important Updates on locally acquired Malaria cases identified in Florida, Texas, and Maryland. http://www.cdc.gov/han/2023/han00496.html
- The Cable. (2024, December 12). Nigeria among top five countries with heaviest malaria burden in 2023, says WHO. https://www.thecable.ng/nigeria-among-top-five-countries-with-heaviest-malaria-burden-in-2023-says-who/
- Montgomery, R. R., & Murray, K. O. (2015). Risk factors for West Nile virus Infection and Disease in Populations and Individuals. Expert Review of Anti-Infective Therapy, 13(3), 317–325. https://doi.org/10.1586/14787210.2015.1007043
