In an attempt to protect older school children from whooping cough, state and county officials are rolling out a free vaccination program that they hope will check the high incidence of the disease in Iowa.

Iowa ranks seventh-highest in the U.S. in cases of whooping cough — the common term for what health officials call pertussis. The Centers for Disease Control and Prevention released numbers that show Wisconsin, Minnesota and Iowa are among the states being hit particularly hard this year.

For example, Iowa has 1,306 cases to date, up from 232 at this time in 2011, a 436 percent increase. Scott County recorded 126 of those Iowa cases in the first nine months of the year. In the first nine months of 2011, Scott County had 36 cases.

“That tends to be the way pertussis works,” said Don Callaghan, the chief of the Bureau of Immunization at the Iowa Department of Public Health. “We do see increases of it every three to five years.”

Whooping cough is a respiratory illness that causes severe coughing spells, which might be followed by vomiting. The disease begins like a cold, with a runny nose and an irritating cough. It is characterized by severe coughing spells that may end in a “whooping” sound when the person breathes in. The disease is spread through the air when infected people cough or sneeze and others inhale the infected droplets.

The disease affects adults and children, but is most serious in babies and the very elderly. Those most affected tend to be students 10 to 12 years old.

The Scott County Health Department is in the process of setting up clinics to distribute the TDaP vaccine booster, which includes protection against pertussis, to all students in grades 6-12. A little more than half of them already might be vaccinated, said Callaghan, who said that 54 percent of all Iowa adolescents are protected against the disease, according to the latest survey numbers.

Scott County health officials will supply 15,000 consent forms for parents of students in public and private schools. Included are the Bettendorf, Davenport, North Scott and Pleasant Valley districts.

Schools will distribute the forms, and parents are asked to return them to the schools by Nov. 1. Lightly and heavily populated counties around Iowa have volunteered for the program, including Cedar County in eastern Iowa, Polk County in the center of the state and Linn County, which includes Cedar Rapids.

The children whose parents give consent can be vaccinated at some point during the 2012-2013 school year. Scott County’s school district clinics should begin in December or January, said Amy Thoreson, the deputy director of the county health department.

Next year, it is anticipated that the Iowa Board of Health will approve rules requiring proof of vaccination for students entering the seventh grade. Such regulations will be voted on at the state board’s November meeting, Callaghan said.

Iowa is one of only 10 states that do not require the booster shot. Illinois began the program during the previous school year. Students entering the sixth and ninth grades need to show proof that they have received a TDaP booster before they can attend classes. That doesn’t mean the disease isn’t still a force to be reckoned with in Illinois, though. While Iowa ranks seventh nationally in the incidence of pertussis, Illinois is 15th. And as of Sept. 20, the CDC says, 48 states and Washington, D.C., have reported increases compared with the same time period in 2011.

Kids with pertussis get what Dr. Greg Garvin calls the “100-day cough.” It seems to take months for them to quit coughing, he explained. Garvin is a pediatrician with Genesis Health System who also serves on the Scott County Board of Health.

Younger children are immunized, but it is not effective for infants less than 6 months of age, and the protection wears off at about age 11. That’s because the actual vaccine is not as strong as it was in the past, said Dr. Louis Katz, the medical director of the Scott County Health Department.

The stronger dose in years past caused more adverse reactions in people. The current vaccine offers a bit less immunity, but it requires booster shots.

“Those risk/benefit trade-offs really only become quantifiable after years of use,” Katz said.

A total of 32,000 cases and 15 deaths from whooping cough have occurred nationally so far this year, according to the CDC. The greatest percentage of deaths, by age group, has been to infants 3 months and younger.

“That’s really what we are trying to prevent,” Thoreson said of the new vaccination program in Scott County.

The increase in whooping cough is a public health concern across most of the nation, said Callaghan, who works at the state level. “Now we need to go ahead and see what we can do to decrease the number of cases we are seeing,” he added.