The Centers for Disease Control and Prevention is working with Southwest Airlines to contact travelers who may have been exposed to measles.
A traveler who was later diagnosed with the highly contagious virus took four flights between Dallas, Houston, and Harlingen, Texas on August 21 and 22.
Health officials say the infected patient traveled through Houston Hobby Airport last month and sat in waiting areas between flights.
The Houston Health Department is also assisting in the investigation and adds the patient did not leave the airport or visit any airport restaurants.
Symptoms of measles include rash, high fever, cough, runny nose, and red, watery eyes. Any person who develops symptoms should call their doctor. The health department says passengers exposed to the patient may develop symptoms as late as Sept. 12.