ST. MARIES - Whooping cough has spread to 16 children in Benewah County in a slow-moving outbreak that has landed one child in the hospital.

Children diagnosed with whooping cough, or pertussis, range in age from 3 months to 17 years and in locations from Fernwood to Santa to St. Maries. The hospitalized child has returned home and is improving.

"We suspect exposures are occurring at a couple of churches and daycares," said Jeff Lee, Panhandle Health District epidemiologist. "Pertussis is highly contagious in group settings - within families, work settings."

Most of the children with pertussis were not immunized. The pertussis vaccine protects people from getting the disease, but it doesn't work completely for all people. Still, it has been shown to prevent serious symptoms in people who have been vaccinated.

The first known case in Benewah County was reported May 27. Eleven cases have been confirmed by nose and throat swab testing. Five additional cases are probable, but have not been confirmed with a test.

Since January, 24 cases of pertussis have been reported in the five northern counties - eight in Kootenai County and 16 in Benewah County. Last year, northern Idaho had 74 cases of pertussis with no deaths. The five North counties typically report six or seven cases of whooping cough per year.

Pertussis is among the diseases childhood vaccinations help prevent. It's a highly contagious illness characterized by severe coughing spells that can cause vomiting and lack of breath. Untreated, pertussis can develop into pneumonia, seizures and encephalitis.

It's particularly dangerous for children younger than one year of age. Most pertussis deaths occur in unvaccinated children or in children too young to be vaccinated.

Pertussis typically starts with a runny nose and watery eyes, but a cough takes over in a week or two. Anyone with symptoms should contact a doctor. People spread pertussis by coughing or sneezing while they're in close contact with others, who then breathe in the pertussis bacteria.