Boston, MA., 07/07/14, Two month old Saoirse Ball, cq, gets the whooping cough vaccine at Mass General Hospital. Her mother is Erinne, cq. Suzanne Kreiter/Globe staff (The Boston Globe.
Boston, MA., 07/07/14, Two month old Saoirse Ball, gets the whooping cough vaccine at Mass General Hospital. Her mother is Erinne.
Suzanne Kreiter/Globe staff

Until recently, pertussis was a disease of the past. Modern vaccinations nearly wiped it out, but the stubborn disease, commonly known as whooping cough, has reemerged in recent years. Now, in an attempt to control the outbreak, doctors and health officials are urging susceptible people to get booster shots while they develop a more effective vaccine.

What is pertussis?

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Pertussis (a.k.a whooping cough) is a highly contagious, potentially fatal disease characterized by violent coughing attacks. The cough makes it difficult to breathe and patients often make a “whooping” noise as they gasp for air, giving the disease its nickname. Here’s what it sounds like.

Whooping cough is particularly severe in infants and young children as the disease can quickly escalate into pneumonia and other lung infections. Since early whooping cough symptoms resemble those of the common cold, babies often catch the disease from family members who aren’t aware they have it.

A history of the disease

Before the whooping cough vaccine was developed in the 1940s, the United States saw as many as 200,000 whooping cough cases and 9,000 whooping cough deaths per year. According to the Centers for Disease Control and Prevention (CDC), the original vaccine proved largely effective at controlling the infectious disease and cases dropped by about 80 percent until the turn of the century,

However, the vaccine was redesigned in the late 1990s after continued complaints about side effects from the shot, according to the CDC. To minimize adverse reactions, researchers replaced the whole-cell vaccine (contains the entire bacteria) with an acellular vaccine (contains only fragments of the bacteria.) While the new vaccine is safer it also less effective and is likely driving the disease’s comeback.

The resurgence

Reported pertussis incidence by age group: 1990-2013
Reported pertussis incidence by age group: 1990-2013
CDC, National Notifiable Diseases Surveillance System and Supplemental Pertussis Surveillance System

The disease has reemerged in the past decade raising serious concern among health officials. The number of whooping cough cases surged to nearly 50,000 in 2012, the highest level the United States has seen since the 1950s. Cases went down slightly in 2013, but whooping cough is back on the rise this year.From January 1 – June 16, 2014, nearly 10,000 cases of whooping cough were reported to the CDC, a 25 percent increase from the previous year.

Whooping cough’s comeback can be attributed to a combination of causes, including a less effective vaccine, low vaccination rates, and the emergence of vaccine-resistant mutant strains of the bacteria.

In 2012, The American Society for Microbiology found that mutant pertussis strains are increasingly common in the United States. The study notes that there is no evidence to prove that the new acellular vaccine led to the rise of these mutant strains. Further, even if vaccine-resistant strains do exist, the vaccine still protects against the dominant form and substantially decreases ones risk of catching the disease.

Is it preventable?

Yes, the whooping cough vaccine, known as DTaP, significantly reduces ones chance of getting the disease. The CDC recommends infants get a five-dose series of the vaccine at ages 2, 4 and 6 months, between 15 and 18 months, and again between 4 and 6 years old. An additional dose of the vaccine is recommended when children are between 11 and 12 years old.

Health officials are recommending booster shots

In response to the current whooping cough resurgence, state health officials are urging more people to get booster shots. Dr. Lawrence Madoff, director of the Division of Epidemiology and Immunization at the Massachusetts Department of Public Health spoke with the the Boston Globeabout the importance of booster shots in controlling the growing epidemic. Booster shots are an additional dose of the vaccine that “boosts” the immune system and increases immunity to the bacteria.

The effectiveness of the whooping cough vaccine fades with time, Dr. Thomas A. Clark, director of the CDC’s Meningitis and Vaccine Preventable Diseases Branch, explained to The Boston Globe. The DTaP shot is about 98 percent effective in its first year, but declines to about 70 percent effectiveness after five years, he said.

Health officials are recommending adolescents, pregnant women, and anyone in contact with newborns, such as fathers, grandparents, and daycare workers, get an additional booster vaccine.

“The public at large and even physicians in general are inappropriately secure that early immunization has taken care of the problem and this is a disease of the past,” Dr. Jeffrey Gelfand, an infectious disease physician at Massachusetts General Hospital and professor at Harvard Medical School, told The Boston Globe. “The public still needs additional education. The public needs to be aware that we’re more susceptible than perhaps even 10 years ago.”