A Baltimore County teacher has been diagnosed with a probable case of pertussis, better known as whooping cough, school and health officials say.

The fifth-grade teacher at Harford Hills Elementary School in Carney was sent to the hospital Monday after complaining she felt ill.

The school sent home a letter informing parents to keep an eye out for symptoms of the disease, which include a low fever, runny nose, vomiting and a distinctive cough that gradually becomes more severe.

School spokesman Charlie Herndon said the diagnosis is not yet confirmed, and no other cases have been reported.

"We are working with the health department as we would in any case," he said. "Primarily we want to make sure the population at Harford Hills are aware that this was a possible case of pertussis."

There have been 294 recorded cases of whooping cough in the state this year, according to Monique Lyle, a spokeswoman with the Baltimore County Department of Health, and 48 probable or confirmed cases in the county.

Lyle said that the department has attempted to track the disease and determine who else might be infected within the community or school system.

She said while children 2 and over commonly receive a vaccine, DTaP, which immunizes against whooping cough, tetanus (lockjaw) and diphtheria, children around age 11 do not typically receive the booster shot that prevents these diseases.

"Sometimes it just goes unnoticed by parents and slips between the cracks," she said.

Lyle encourages caregivers to receive a Tdap vaccine, the vaccine for adults 19 years and older, because the disease is particularly deadly to children younger than 1.

Whooping cough has become fairly uncommon since the Tdap vaccine was licensed in 2005, though this year the number of reported cases to the Centers for Disease Control and Prevention has spiked to more than 34,000 through Oct. 27.