Whooping cough is now an epidemic in Washington state. Families have been hit hard.

Chelsey Charles only has photographs to remember her daughter by. In 2011, Kaliah died of the highly contagious but preventable disease - whooping cough. Kaliah got it from her mother the baby was only 27 days old.

That's why Chelsey has become such an advocate for teens and adults to get the t-dap booster shot - the shot she didn't get, the shot that could have prevented Kaliah's death.

Chelsey lives in Snohomish County, which used to be the only hot spot for whooping cough in our state. Not anymore. The disease has now spread to 27 Washington counties. The hardest hit include Whatcom, Skagit, Snohomish, and Jefferson in the Puget Sound region.

Statewide, there have been more than 1200 cases this year compared with just 128 in 2011.

In the 13 years since I've been Secretary of Health, I have never declared an epidemic before, said Mary Selecky

Whooping cough, or pertussis, is known by its distinctive whoop and how long it lasts.

Before the 1950s, whooping cough killed thousands of children every year. Then came the vaccine. A combination shot for diphtheria pertussis - tetanus, also known as the DPT vaccine

By 1976 the number of cases had plummeted to all time low. Some thought pertussis was about to be eradicated. But the numbers started climbing again in the 1980s. The vaccine had side effects: high fevers, seizures, vomiting.

Parents became reluctant to vaccinate their children even though the disease itself can be fatal to babies.

A safer version of the vaccine called Dtap was introduced in the late 90s. It is far less likely to cause side effects. But some parents still are not vaccinating their children.

That's one reason why Washington state now has dubious distinction of having the highest rate of whooping cough cases in the country. Skagit County has become the new hot zone.

Three-year-old Talon Thompson was recently exposed to a relative with whooping cough.

We just want to get it checked out and see, just to make sure and the last thing we want it something tragic, said dad, Philipo Thompson.

Even though Talon and his family are up to date on their immunizations, the pertussis vaccine wears off in time.

Probably eight out of 10 cases we report are fully vaccinated, said Sandi Paciotti, Skagit Co. Health Dept

Paciotti says that's why doctors and health departments are pushing the booster shot.

If you have been vaccinated, you're likely to have a less severe case. The unvaccinated, I've seen with cases are still coughing at three months, she said.

Most of the cases are showing up in schools. Becky Neff is the school district nurse who hears every day what the disease can do.

They've coughed so hard their ribs hurt, I coughed so hard last night I couldn't sleep. I coughed so hard I threw up, said Becky Neff, School District Nurse.

And then there are the stories like Kaliah's - that end in heartbreak.

They turned off the machine and she tried to take a breath and then she was just gone, said Chelsey.

Wednesday night it was clear people were getting the message. A free shot clinic in the Snohomish County mountain town of Darrington drew 130 people.

Some like Jennifer Nolan drove over an hour to get vaccinated along with her husband Dan. The couple could not affortd the 60 to 90 dollars being quoted for a shot at a pharmacy. When you are on a basic $11 dollar an hour salary with no health insurance, yeah I'll drive, Nolan said.

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