Adult booster shots could shield those too young for vaccines.
© St. Petersburg Times, published September 11, 2001
WASHINGTON -- Whooping cough is one of those diseases most people think is history, but the dangerous germ that can leave sufferers gasping for air is making a comeback.
The cough so strong it can break a rib once hit mostly babies and toddlers, but it's striking more and more teenagers and young adults. Apparently the whooping cough vaccinations Americans get as babies eventually can wear off.
Here's the real risk: While older people usually recover, they can easily spread the illness to infants too young for vaccinations. Whooping cough can kill babies.
So experts warn new parents to keep infants away from anyone who's coughing, even as scientists study whether millions of Americans should start getting booster doses of whooping cough vaccine just as many get regular tetanus shots.
The goal is to develop boosters for older children and adults so there's "a wall of protection around the newborn baby," explains Dr. Michael Decker, a Vanderbilt University professor who has studied whooping cough, also called pertussis, for 20 years.
He just joined vaccine manufacturer Aventis Pasteur, which is working to bring a booster shot sold in Canada to this country.
Pertussis is a bacterial infection that at first seems like a cold: a runny nose and hacking cough, first at night and then during the day. Coughing fits begin a week or two later, up to 15 coughs in a row followed by a high-pitched "whoop" as patients gasp for air.
Infants are more likely to turn bluish than whoop as they run out of air. They can get pneumonia and become dehydrated and malnourished.
For teens or adults, the severe coughing can cause vomiting or a hernia, even break a rib.
Consider Decker's experience. "I got it off my 15-year-old this January, and I was coughing for three months," he said. "I could feel my throat closing up and tightening, and I started choking and gagging. It was a revelatory experience for someone who's written the words and not experienced the feeling."
Often, though, older patients have a milder illness, just a nagging cough. So they don't see a doctor, or it's misdiagnosed as bronchitis, because pertussis testing is difficult. Indeed, a Vanderbilt study found that about one-fourth of teens and adults with prolonged coughs unknowingly have pertussis. It's most contagious during the first three weeks.
The Centers for Disease Control and Prevention counted 56,775 whooping cough cases during the 1990s, a 51 percent increase from the 1980s, and a rise that's continuing.
Last year, CDC had reports of more than 7,000 cases, and "we suspect there may be 10 times that amount" because of underdiagnosis in teens and young adults, said Dr. Kris Bisgard, a CDC epidemiologist.
That's a far cry from the 250,000 Americans who got pertussis annually before vaccinations began in the 1940s. But it's far worse than 1980, when there were only about 1,000 cases a year.
The biggest rise: CDC figures show for every 1-million 10- to 19-year-olds, three got pertussis in 1980 vs. 70 cases per million older children last year.
They in turn can infect vulnerable infants. Pertussis rose 37 percent among babies in the 1990s, almost exclusively among those younger than 4 months. That's when infants get their second dose of pertussis vaccine, and protection begins kicking in.
Today, Americans get their final dose of pertussis vaccine by age 6.
Studies show that giving one-third of the youngster's dose to teens and adults boosts their immunity nicely, CDC's Bisgard said. Canadians already can get such a booster dose.
Americans can get booster doses of tetanus and diphtheria vaccine every 10 years. (You call it a tetanus shot, but the two almost always come together.) The idea: Just add a pertussis booster to that shot. After all, babies today get diphtheria, tetanus and pertussis vaccine in the same shot, called DTaP.
Aventis and a competitor, GlaxoSmithKline, are studying boosters, Bisgard says, and experts expect one will hit the market in about two years.
For now, what's the advice?
Keep infants away from people who have any cough illness, Bisgard said -- and make sure they're vaccinated on time.
DTaP doses are given at ages 2, 4 and 6 months, again at 15 to 18 months and a final dose between 4 and 6 years.