Whooping Cough: Rise in Cases Makes It ‘Worth a Shot’

Released: 18-Aug-2010 10:10 AM EDT
Source Newsroom: University of Texas Health Science Center at Houston
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Newswise — If you think you shouldn't be worried about your child's—or your—lingering, nagging cough, think again. Pertussis has reemerged on the scene. In what some public health officials are calling the worst outbreak in 50 years, pertussis, better known by its unique sound—whooping cough, has been found in six states with 1,500 cases reported, six of them fatal.

It's probably time to check that immunization record.

"As parents, we should take every opportunity to get immunizations for our children—and ourselves—and get them in a timely fashion," says Lynnette Mazur, MD, professor of pediatrics at The University of Texas Medical School at Houston. "But, first, get your child to a doctor for a proper diagnosis if he or she has a runny nose or cough that lasts more than a week."

So, pertussis is back, huh. (Did it ever really go away?) Mazur says that although pertussis has always been with us, it is spreading this time around for three reasons: the weakening of the vaccine's protection over time, gaps in “herd immunity” and its high contagion factor.

"The vaccine has a limited effectiveness time span, lasting only six to10 years," Mazur says. "Outbreaks cycle every three to five years and then settle down. But it's always there."

She explains that for the pertussis vaccine to be effective against serious outbreak, “at least 92 to 94 percent of the community must be vaccinated.” This defines the “herd” in herd immunity: The more contagious the disease, the greater the density needs to be of vaccinated populations.

“Pertussis is so contagious that the average number of secondary infection cases that are produced by a single index [first identified] case is 12 to 17,” Mazur says.

Pertussis stems from invading bacteria in the nose, mouth and throat called Bordetella pertussis. It is spread through the air by droplets produced from the coughs and sneezes of contagious people. Although it only mildly affects immunized school-aged children and adults, it can be serious in infants younger than 1 year. Seizures, pneumonia, and in rare cases, brain damage and even death may occur. Up to 1 percent of children with pertussis die from the disease.

Signs of pertussis show up most commonly seven to 10 days after exposure but the range of incubation can be as wide as four to 21 days. Mazur says symptoms can be hard to detect at first because pertussis mimics a cold—runny nose, low-grade or no fever and mild cough. Many whooping cough sufferers appear well.

Classic whooping cough can be a violent assault on the body, with spasms of coughing followed by a “whooping” sound when the patient tries to take a breath. No amount of cough syrup quells the cough. What parents and patients need to know is that the cough itself can linger for months.

The standard preemptive strike is DTaP, a combination vaccine that protects against diphtheria, tetanus and pertussis and remains the vaccine of choice. The Centers for Disease Control and Prevention (CDC) recommends that by age 7, children should have received DTaP shots at 2, 4 and 6 months and once between 15 and 18 months, and again between 4 and 6 years.

Adults should substitute one of their 10-year tetanus/diphtheria (Td) boosters with a one-time DTaP dose.

"There used to be a reluctance to immunize a person older than age 7 because of the severe side effects of the first pertussis vaccine," Mazur explains. "With DTaP's formulation, there are fewer bad reactions and we have a safer vaccine."

Mazur says it's possible that older children and adults should be encouraged to get vaccinated to protect against the spread of pertussis. "We need to look at adults, who are a big reservoir for pertussis," Mazur adds. "Adults may need a shot every 10 years, but more research is needed to find an even better vaccine."

Researchers are looking at new ways to reduce the number of shots and come up with vaccine formulas specifically created for adults to reduce the spread of pertussis.

Don't self-diagnose. Get a check-up. That visit to the doctor's office could prevent that cough from getting out of hand.

"Pertussis can progress. The best chance of treatment is an early start on the antibiotic, erythromycin, which can shorten the course," Mazur says. Studies indicate that two other antibiotics are effective in previously immunized people—azithromycin or clarithromycin—6 months or older.

In the end, Mazur says, immunize, immunize, immunize. "The combination vaccine is the best way to prevent pertussis. And it requires fewer pokes. That's even more good news for our children."

Written by Jacquelyn Preston and Karen Krakower Kaplan


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