DENVER (CBS4) – Colorado health officials are warning parents to be sure their children are fully immunized as whooping cough continues to be on the rise in Colorado.

The spike is serious, especially for young children. In Boulder County alone they’ve seen 114 cases since January — a 10-fold increase over last year.

One Denver baby barely survived the serious illness. Ten-week-old Jeremiah Castillo still has a little cough.

“That cough is really mild, really mild compared to what it was,” Jeremiah’s mother Valerie Castillo said.

Seven weeks ago the newborn was in intensive care for 13 days. It all started with what doctors diagnosed as a common cold.

“I had him sleep on my chest and I felt him stop breathing. I flipped him over and he was purple,” Valerie said. “When I flipped him over I thought he had passed away.”

Valerie raced to a hospital. Her son was then rushed to another.

“In the ambulance he stopped breathing twice,” she said.

Jeremiah had whooping cough or pertussis. He was sedated on a ventilator and fed through a tube.

“Everybody that came to visit him that went into the room left crying,” Valerie said.

“It’s something we’re very concerned about,” Colorado Immunization Director Dr. Rachel Herlihy said.

Herlihy says Colorado is in the midst of an epidemic with 940 cases of pertussis so far compared with the usual 200 or less.

“We do expect the number of cases to increase, especially now that school is back in session,” Herlihy said.

Health officials say get children vaccinated starting at eight weeks and all adults.

“It’s grandparents, it’s parents, it’s pregnant women, it’s child care workers, school teachers, all of those people.”

Health officials say if your child does get pertussis seek medical attention and keep him or her out of school and on antibiotics for five full days. If children go back too early they can spread the infection.