Parents of West Junior High School students were informed Friday that one of their children’s classmates had been diagnosed with whooping cough and a second student could be infected.

Whooping cough, or pertussis, is a highly contagious bacterial infection of the respiratory system. The disease gets its name from the characteristic sound made by infected individuals when they try to inhale during a coughing fit. Most children are vaccinated against the disease as infants, but the vaccination becomes less effective as people age.

In a letter sent home with students, school officials encouraged parents to keep a close eye on their children for signs of the illness, and to keep possibly infected children away from school and child care.

Katy Buck, nurse facilitator for USD 497, said the district would be asking parents of West Junior High students who had not been immunized to keep their children out of school for five days. That was part of a plan recommended to the district by the Lawrence-Douglas County Health Department to limit the spread of the infection.

The health department informed the school district of the confirmed whooping cough case late Thursday afternoon.

“Our role in the schools is really to take directives from the health department,” Buck said.

She said the measures so far had been limited to West Junior High, but one of the two students at West had a sibling at Free State High School who may have been exposed to the disease.

A whooping cough infection typically begins with coldlike symptoms: a mild-cough and low fever. The cough builds in frequency and intensity until an infected individual begins having coughing attacks, which can result in vomiting. The disease typically passes in four to six weeks, though a mild cough may persist for months.

Whooping cough generally presents itself mildly in adults and older children, but can pose significant health problems to children younger than a year old.

Whooping Cough home page Medline plus: Whooping Cough

The disease is spread through the airborne droplets emitted when an infected person coughs. People who have not been vaccinated for whooping cough are likely to contract it if they spend a significant amount of time in the presence of an infected person.

On a positive note, Buck said the coming holiday break would help prevent spread of the disease in the schools.

“The schools will be closed for two weeks, so there won’t be as much proximity and chance for spreading,” she said.

Just this week, the Kansas Department of Health and Environment announced there had been a significant increase in the number of whooping cough cases in the state. There have been 90 confirmed cases of the disease in 2004, up from 23 confirmed cases in 2003. Between 1999 and 2001, the average annual number of confirmed cases was 18.

More than a third of this year’s confirmed cases — 39 altogether — have appeared in six northeast Kansas counties: Douglas, Franklin, Leavenworth, Johnson, Miami and Wyandotte, officials said.