Washington state’s worst outbreak of whooping cough in decades has prompted health officials to declare an epidemic, seek help from federal experts and urge residents to get vaccinated amid worry that cases of the highly contagious disease could spike much higher.

It’s the first state to declare a whooping cough, or pertussis, epidemic since 2010, when California had more than 9,000 cases, including 10 deaths. Washington has had 10 times the cases reported in 2011, and so has Wisconsin with nearly 2,000 cases this year, though that state has not declared an epidemic.

California responded to its crisis two years ago with a public information campaign, readily available vaccines and a new law requiring a booster shot for middle- and high-school students. Doctors were urged to spot whooping cough early, send infected babies to the hospital and promptly treat those diagnosed. In 2011, the number of cases there dropped significantly.

In Washington, about 1,280 cases have been reported in 2012, and officials believe the state could see as many as 3,000 cases by year’s end. Health Secretary Mary Selecky declared the epidemic April 3, and since then officials have bought up the vaccine and made it available for free for people who don’t have insurance.

State officials have asked hospitals to vaccinate every adult who goes home with a new baby, and urged businesses to encourage their employees to get the adult booster shot. Washington already requires a booster shot for middle- and high-school students.

Last week, Gov. Chris Gregoire announced the state is putting $90,000 into a public awareness campaign and diverting some federal money to pay for 27,000 doses of vaccine. The state has also asked the Centers for Disease Control and Prevention to send a special team of investigators and an epidemiologist to the Washington.

State epidemic declarations are up to the states; there are no federal regulations for such decisions. Selecky said this is the first time in 14 years she has declared a state epidemic, but felt she needed to take action to stop the disease from spreading further.

“When we’ve looked historically, we’ve seen nothing like this,” she said. “We’re taking this very seriously.”

Adults and teens need booster shots so they don’t give pertussis to the babies in their lives, said CDC spokeswoman Alison Patti

“We want to create a cocoon of protection around them,” she said. “We’re really worried about keeping babies safe.”

Pertussis is known as whooping cough because of the “whooping” sound people often make while gasping for air after a coughing fit. A highly contagious bacterial disease, it starts off like a cold but leads to severe coughing that can last for weeks. In rare cases, it can be fatal.

Until routine child vaccination became widespread in the 1940s, pertussis caused thousands of fatalities each year in the United States. While deaths are uncommon today, they still occur: In recent weeks, infants in New Mexico and Idaho have died from the disease.

Because the adult booster for pertussis — called Tdap for tetanus, diphtheria and acellular pertussis — has only been available since 2005, fewer than one in 10 adults have gotten the shot and most don’t even know they need it. The numbers are better for teens: about 70 percent have received a booster shot. Most people do not find out they even need a booster until they go to the doctor for a tetanus shot, Patti said.

Patti emphasized that pertussis isn’t spreading because of an anti-vaccine movement. Among possible reasons for the recent spike are that diagnoses in teens and adults are getting better and doctors are doing a better job with reporting, she added

Health officials say the disease tends to return in three-to-five-year cycles.

“The incidents tend to oscillate,” said Herbert Hethcote, a professor emeritus from the University of Iowa who is a specialist in mathematical modeling of the spread of infectious diseases,

He said the growth of pertussis in Washington state has followed a pattern: As the population ages, the immunity level goes down because the vaccine is wearing off. The disease spreads and the cases grow until more people get the vaccine and the numbers go down again.

Hethcote said his daughter had whooping cough as an adult during the last spike of cases in Washington, four or five years ago. She coughed so hard she broke a rib and was sick for more than a month, he recalls. She never found out how she caught it but the experience raised awareness in his family that pertussis is not just a children’s disease.

###
The Associated Press