The U.S. is on track to have its biggest whooping cough epidemic in 60 years, with more than 21,000 cases already reported in 2012.
The highly contagious and potentially fatal disease, officially known as pertussis, starts with cold symptoms and progresses to coughing bouts severe enough to leave patients gasping for air.
Yvonne Maldonado, MD, is Lucile Packard Children’s Hospital’s service chief of pediatric infectious disease and a professor of pediatrics at the School of Medicine in Palo Alto.
Q: Who gets hit hardest by pertussis?
Maldonado: Young infants under a year — especially babies under 6 months of age — are most vulnerable to complications of pertussis, with about a dozen babies dying in the U.S. each year.
The disease is caused by a bacterium, Bordetella pertussis, that produces many different toxins. These toxins stimulate the body’s immune response, making our airways very inflamed and swollen.
Because babies have small airways, the swelling leaves a very small area for air passage to occur.
When they’re trying to breathe, babies with pertussis have to take this really big breath, producing the classic “whoop” sound. They can have apneic spells, when they stop breathing, and can also develop secondary bacterial pneumonia.
We can get rid of B. pertussis bacteria with antibiotics, but the toxins that cause airway swelling do not go away with antibiotics. That means babies can be sick for weeks to months.
Q: Why does the United States have so many cases of pertussis this year?
Maldonado: We’re headed to the worst year since vaccination began several decades ago, but nobody really knows why. One theory is that the vaccine may not be as effective as we thought.
Historically, we used a vaccine consisting of whole pertussis bacteria that were treated and killed, but that vaccine caused symptoms such as fevers. The vaccines now used, which were first licensed in 1991, instead contain components isolated from the bacteria.
Q: Do we now have an epidemic in California?
Maldonado: No. This year we’ve had fewer than 400 cases, a huge drop in the number of cases. We had our epidemic in 2010, when 10 infants died in California alone. After that, we stepped up vaccination efforts and took a lot of measures at the state level to reduce exposure to pertussis.
Up to 80 percent of babies with pertussis get infected by someone in their household, such as a parent, grandparent or sibling.
Q: Who should get vaccinated?
Maldonado: Infants should be vaccinated at 2, 4 and 6 months, with a booster shot at age 15-18 months and another at age 4-6 years. The pertussis vaccine is among those required for children to enter kindergarten in California. Starting in the 2012-13 school year, California law also requires children entering seventh grade to have a pertussis booster.
Any adult who has not had a booster shot since childhood should also receive the vaccine, regardless of age. And those planning to travel to states with epidemics should get vaccinated rather than changing their travel plans.
Q: Where can families find more information about getting the vaccine?
Maldonado: Ask your primary care physician or your child’s pediatrician for information. Santa Clara County provides information about obtaining low-cost pertussis vaccination for children at http://www.sccgov.org/sites/sccphd/en-us/Residents/IzClinic/Pages/TdapClinics.aspx.
Courtesy Erin Digitale, Stanford School of Medicine.