HAMILTON COUNTY, TN. (WRCB) -- Whooping cough cases are on the rise in Hamilton County.

Health officials can't pinpoint where it started, or how it is spreading, but they predict the colder months could lead to more cases.

That's why they're urging doctors, pharmacists, and patients to prepare.

The Chattanooga-Hamilton County Health Department has confirmed 21 cases of whooping cough.

"We typically see five to ten cases a year, so this increase is concerning to us," says Margaret Zylstra

Pertussis, commonly called whooping cough, is a bacteria that attacks the lungs.

A patient develops an uncontrollable cough that can cause vomiting, breathing problems, and a high pitched whooping sound.

"This cough can sometimes last for weeks or sometimes even months," says Zylstra.

Margaret Zylstra says the increase reflects a national trend.

"All children should be vaccinated and adults should receive a booster," she says.

"We should have a stock of 30 doses at least tomorrow," says Michelle Hooton.

Access Family Pharmacy will offer the vaccine beginning Thursday.

Michelle Hooton says health department officials sent a letter notifying her of the spike.

"They are advising that physicians don't miss an opportunity to go ahead and vaccinate their patients," says Hooton.

Infants can be vaccinated at two months old.

It takes a series of four vaccines to be protected, and a booster is recommended at ages five and 11.

But the vaccine doesn't protect everyone.

Sixteen of the 21 cases in Hamilton County have been in children under the age of six.

"Some of the cases were too young to receive all of the vaccines that they needed, so they weren't fully protected," Zylstra says. "And again, no vaccine is 100 percent."

Zylstra says the best way to protect children is for the people around them to be vaccinated.

Zylstra says most adults had the vaccine as children, and only require a booster.

She denies the recent cases being located to any one school or location.

Deaths associated with whooping cough are rare, but most commonly occur in infants.

Whooping cough is usually treated with a round of antibiotics.