An increase in confirmed cases of whooping cough has state and local health officials urging people to make sure children are immunized against the infection.

Whooping cough is a highly contagious respiratory disease potentially fatal for children.

It is spread when an infected person talks, sneezes or coughs. Vaccinations prevent it.

Kansas Department of Health and Environment officials have confirmed 31 cases of whooping cough, also known as pertussis, since May. That’s high compared with the average of nine confirmed cases during the same months for the past three years, said KDHE spokeswoman Sharon Watson. In 2002, there were 23 confirmed cases of whooping cough the entire year.

“We’re certainly monitoring the situation, and this is an upsurge in terms of what we expect to see,” Watson said.

Watson said the bulk of the cases had been in northeast Kansas.

Two of the confirmed cases are in Douglas County. Kim Ens, disease control program coordinator for Douglas County, said that’s not unusual. But the increase in the cases statewide has county health officials taking action.

“What we’re really recommending to physicians is to be suspicious of anyone, especially children, who have had that prolonged coughing, especially if they have that whoop sound, and to think about testing for it,” Ens said.

The Health Department also is encouraging people to make sure children are up to date on their vaccinations against whooping cough. The vaccination is 80 to 85 percent effective, Ens said.

6News video: Whooping cough cases increasing Audio: Kim Ens, disease control program coordinator for Douglas County, on whooping cough cases in Douglas County. Audio: Ens on who is at risk for contacting pertussis. Audio: Ens on adults who may have pertussis. Audio: Ens on the immunization regimen. Audio: Ens on preventing the spread of the disease. Audio: Ens on the need for vigilance. MedlinePlus: Whooping Cough

No vaccination is available for people older than age 7, but the infection isn’t as severe in adults, Ens said.

One of the two Douglas County cases was a child who hadn’t been immunized. The other was a child who had only received one round of the vaccination, Ens said.

“And that’s what we’re seeing across the country,” she said. “Most of the cases are in children that are not up to date in their vaccination. Diseases like this run in cycles. Some states have been seeing definitely epidemic numbers, and in Kansas we are seeing increased numbers, and so that’s why we’re really trying to let doctors be suspicious of it.”