By JoNel Aleccia

Nearly 400 cases of pertussis, or whooping cough, have been diagnosed in Washington state so far this year, compared with 85 a year ago.

Whooping cough is continuing to rise in Washington state, particularly among babies too young for vaccination and teens with waning protection, health officials reported Tuesday.

As of April 25, there were 387 cases of pertussis, also known as whooping cough, in Washington, compared with 85 reported cases at the same time last year. Twenty-five of those cases were in babies younger than 1. Of those, six babies were hospitalized, including five aged 3 months or younger.

Pertussis is known for causing uncontrollable coughing that can make it hard to breathe and cause a characteristic “whooping” sound in someone struggling to get air. It can be dangerous, even deadly, for babies and young children.

This is the first sharp rise in cases since a 2012 epidemic that saw nearly 5,000 cases in Washington.

The new cases have technically nudged the state over what’s known as the epidemic threshold, the level at which disease is considered widespread. But pertussis rates have ranged widely among counties, with higher levels in Walla Walla, Jefferson and Kitsap counties, where rates are at least 34 per 100,000 people, and lower rates in King County, with a rate of 2.7 cases per 100,000 people, and Snohomish County, with a rate of 6.3 per 100,000 people.

Twenty-four Washington counties have reported some pertussis activity; 15 have seen none, officials said.

More than 28 percent of the cases so far are in the youngest kids, but more than half are in older kids and teens, ages 10 to 18. That’s likely because of waning effectiveness of the vaccine that protects against pertussis.

Health officials are urging pregnant women and anyone having contact with young babies to get vaccinated against pertussis. Teens may also need booster shots if they haven’t been fully immunized. And everyone should seek medical care and antibiotics at the first sign of illness, officials added.