Staff Report
SAN MARCOS — The Hays County Health Department (HCHD) received notification from the Texas Department of State Health Services (DSHS) Aug. 12 of the first laboratory-confirmed human case of West Nile Virus (WNV) in Hays County during the 2026 mosquito season.
To protect the patient’s privacy and confidentiality, HCHD will not provide further details about the case.
The confirmation comes as West Nile Virus continues to be detected in mosquito populations throughout the county. The Hays County Development Services (HCDS) Mosquito Surveillance Program received confirmation that a mosquito trap sample collected Aug. 11 in the 78666 ZIP code in San Marcos tested positive for WNV, marking the sixth WNV-positive mosquito pool reported through the county’s surveillance program this season, with one positive trap in Buda.
The city of San Marcos has reported two additional positive mosquito pools, bringing the total number of positive mosquito pools reported throughout Hays County to eight.
“West Nile Virus activity in both our mosquito population and now a confirmed human case underscores the importance of taking precautions against mosquito bites,” said Hays County Judge and Director of Emergency Management Ruben Becerra. “Our health department and mosquito surveillance teams will continue monitoring conditions throughout the county, but prevention begins at home. Taking a few simple steps to protect yourself and eliminate standing water can help reduce the risk for our entire community.”
The virus is primarily spread through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds and can then transmit the virus to humans and animals. WNV is not generally spread from person to person, except in extremely rare circumstances involving blood transfusions, organ transplants or transmission from mother to child during pregnancy, delivery or breastfeeding.
About 80% of people infected with WNV do not develop symptoms. Approximately 20% may experience fever, headache, body aches, joint pain, vomiting, diarrhea, rash or swollen lymph nodes. Less than 1% of people infected develop severe illness affecting the central nervous system, such as encephalitis or meningitis. People ages 50 and older, and those with weakened immune systems are at greater risk of developing severe illness.
Symptoms of severe WNV disease can include high fever, neck stiffness, disorientation, tremors, muscle weakness, vision loss, numbness or paralysis. In rare cases, WNV can be fatal.
Anyone experiencing symptoms associated with West Nile Virus is encouraged to seek medical attention. There is no specific antiviral treatment for WNV. Over-the-counter medications may help relieve mild symptoms, while people with severe illness may require hospitalization and supportive care.
“The best action Hays County residents can take to protect themselves from West Nile Virus is to prevent mosquito bites by following the three Ds: Defend, Dress and Drain,” said HCHD Director Matthew Gonzales. “If someone knows they were recently bitten by mosquitoes and is experiencing flu-like symptoms or symptoms associated with West Nile Virus, they should contact a healthcare provider, especially if the patient is immunocompromised or over the age of 50.”
Gonzales emphasized that WNV is not considered contagious between people. Humans are considered “dead-end hosts,” meaning they generally do not develop high enough levels of the virus in their bloodstream to infect mosquitoes and continue the transmission cycle.
HCDS conducts mosquito surveillance from May through November to monitor mosquito populations and mosquito-borne diseases. Mosquitoes are collected using standardized traps, including CDC gravid traps and BG- Sentinel traps and sent to DSHS for identification and arboviral testing. Surveillance helps the county track mosquito activity, identify areas where disease-carrying mosquitoes are present and guide prevention and control efforts.
“It’s essential that everyone helps reduce mosquito populations by eliminating unnecessary standing water around their properties,” said Nick VandenBroek, environmental health specialist II. “Source reduction can go a long way to reduce localized populations of mosquitoes in and around your neighborhood.”
Mosquitoes can breed in very small amounts of standing water. Residents are encouraged to regularly inspect their homes, yards and workplaces and empty or treat water that may collect in flowerpots, buckets, birdbaths, gutters, pet dishes, tires and other containers.
HCHD and HCDS remind residents to follow the three Ds to reduce their risk of mosquito bites and WNV infection:
• DEFEND: Whenever outside, use an EPA-registered insect repellent and always follow label instructions.
• DRESS: Wear long, loose and light-colored clothing when outdoors.
• DRAIN: Drain or treat standing water in and around the home or workplace where mosquitoes could lay eggs.
The departments will continue human health and mosquito surveillance efforts throughout the mosquito season to monitor WNV activity and help protect the health and safety of residents.
For more information about the virus in humans, contact the HCHD at 512-393-5520 or visit www.hayscountytx.gov/373/Current-Public-Health-Situations.
