The city of Sugar Land was notified July 2 that at least one mosquito trapped in the New Territory subdivision tested positive for the West Nile virus, according to a city press release.

In response, the press release said the city will increase citywide mosquito spraying to twice a week and continue to trap and test for the virus in collaboration with the Texas Department of State Health Services.

“Residents should use insect repellent whenever they are outdoors and avoid going outside at dusk and dawn when mosquitoes are most active,” said Joe Anzaldua, the city’s medical director and health authority, in the press release. “People over 50 years old and those with compromised immune systems are at a higher risk of becoming seriously ill if infected with the virus. If people have symptoms that cause them concern, they should contact their health care provider immediately.”

To prevent growth of the mosquito population, residents are advised to drain any standing water around their houses.

Infection from the virus can cause symptoms such as vision problems, confusion and seizures, while the more mild illness West Nile fever can include drowsiness, muscle aches and nausea. According to the press release, about 80% of those infected with West Nile will not experience symptoms and can recover without any medical help. There is no vaccine or treatment for the virus.