The Centers for Disease Control and Prevention says Texas is one of two states showing the highest number of flu cases.
Just this week, the Tarrant County Public Health Department reported a rise in the number of influenza-like illnesses in the county.
"We are seeing reports of increased flu activity locally," said Dr. Lou Brewer, director of the Tarrant County Public Health Department.
Key indicators of flu, according to Brewer, are increased numbers of people visiting their doctor with influenza-like symptoms of a fever above or equal to 100 degrees Fahrenheit, accompanied by a cough or a sore throat.
"With colder weather in the forecast ... it is likely that flu-like illnesses will spread more easily," Brewer said.
Brewer added that practicing good hygiene helps keep such illnesses from spreading.
"Proper hand washing will help keep germs from spreading. Also, cover your coughs and your sneezes, stay home if you're sick and avoid close contact with anyone who is sick," she said. "The best protection is to get a flu shot right away, before the peak of the flu season hits."
According to Brewer, it takes about two weeks for the flu vaccine to take full effect.
Dr. Shelle Barber with Family Healthcare Associates in Arlington told NBC 5 the rise she's seen has been in the "Flu-A" virus.
"Anytime you have flu, you're pretty sick, but a lot of people say Flu A is worse because it's upper respiratory, people tend to get more pneumonias with it. Fever is a little higher, they just feel worse in general," she said.
Health experts said, the flu shot is not a 100 percent guarantee you won't get sick. Barber is an example of that. She received the flu vaccine that offers protection against the four major strains of the flu, but still caught the bug.
"The Friday after Thanksgiving I had a cough, then a 103 fever, three days later, I was out of work for about three days. I did have the vaccine, so I was a little disappointed, but that doesn't mean not to get your shot. It can make it less severe if you have your vaccine," she said.
In recent weeks, there has been a steady stream of people visiting Tarrant County Public Health centers receiving the vaccine.
"We have to remember, we're not only protecting ourselves, we're protecting those around us, especially babies under six months and the elderly," said Rose Mary Bennett, an immunizations specialist.