According to a news release issued by the city on Friday, health authorities don't know where he or she was infected.
In July, city officials were notified that at least one mosquito trapped in the New Territory subdivision tested positive.
Humans can contract the virus from a mosquito bite and infected mosquitoes can get the virus from feeding on infected birds.
The city said crews will continue spraying twice a week and will keep on trapping and testing for the virus in collaboration with the Texas Department of State Health Services.
Sugar Land's medical director and health authority Dr. Joe Anzaldua is urging residents to use insect repellent whenever they're outside.
"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," said Anzaldua. "If people have symptoms that cause them concern, they should contact their health care provider immediately."
There are no medications or vaccines to treat and prevent a West Nile virus infection.
The city said symptoms of the virus may include a stiff neck, vision problems, body tremors, mental confusion, memory loss and seizures. Officials said symptoms of the milder form of the illness, known as the West Nile fever, may include fever, headache, muscle and bone aches, nausea and drowsiness.
People with the milder form of the illness typically recover on their own, although symptoms could last for several weeks.
The city said up to 80% of people infected with West Nile virus will have no symptoms and will recover on their own.
Meanwhile, the Texas Department of State Health Services recommends practicing the "Four Ds:"
- Use insect repellent containing DEET, picaridin or oil of lemon eucalyptus
- Dress in long sleeves and long pants when you are outside
- Stay indoors at dusk and dawn when mosquitoes are most active
- Drain standing water where mosquitoes breed. Common breeding sites include old tires, flower pots and clogged rain gutters.