Whooping Cough Often Passed to Babies by Family

Pertussis (whooping cough), a highly contagious respiratory infection, is on the rise. And according to new research, babies, who are particularly vulnerable to the infection and its severe complications, often catch the illness from family members.

To try to find the source of the infection in infants, a group of researchers surveyed families and caregivers of 95 babies with pertussis in four countries. On average the infants were 3 months old.

When the researchers were able to pinpoint the source of the infection, they found that more than three-quarters of the cases were transmitted by family members or caregivers in the babies' own homes. And about half of those infections came from the infants' parents.

Adults with pertussis may have cold- or flu-like symptoms that can include a bad, prolonged cough, but the illness can be more severe and can lead to complications, like pneumonia, for infants and young children. Caused by infection with the Bordetella pertussis bacterium, pertussis is known as whooping cough because of the distinct "whooping" sound associated with severe coughing fits.

Kids routinely get the tetanus-diphtheria-acellular pertussis (DTaP) vaccine in five doses before their sixth birthday, then a combination booster shot (called Tdap) between 11 and 18 years old.

Babies are particularly vulnerable to the infection because they usually don't get their first dose of the vaccine until they're 2 months old, and only get two more shots during the first year.

The effectiveness of the pertussis vaccine can fade in time. That means teens and adults who were immunized during childhood may still catch and then pass on the infection to babies and young kids who haven't yet been fully immunized.

In many of the cases, researchers couldn't identify the source of the infection, so they cautioned that more study might be needed on this issue.