Study: New age group blamed for spreading whooping cough to infants

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Indianapolis, Ind. (September 16, 2015) - It's long been thought infants catch whooping cough from their mothers, but a new study reveals someone else is likely the source of infection.

A new study in the journal Pediatrics says infants are most likely to catch it from siblings.

Whooping cough is a highly contagious respiratory disease.

"It usually starts with a few days or week of a cold-like symptom," said Dr. Christopher Belcher, Director of Pediatric Infectious Disease for Peyton Manning Children's Hospital. "Runny nose, stuffy nose, low grade fever and cough. But then as that fades away, the cough becomes more pronounced and there are fits or spells or spasms of cough that can lead to gasping and color change and difficulty breathing."

Moms-to-be are vaccinated during pregnancy. Dr. Belcher says it's important the entire family get the vaccine.

"We're now vaccinating moms during pregnancy for whooping cough. Before that, we were vaccinating them at the time of delivery. So now mom's slice of the pie is getting smaller and what we're seeing in studies is that siblings are becoming much more of a source."

The study shows about 35% of cases originate from siblings, about 20% come from mothers and about 10% come from fathers.

So how long is an infant in that high-risk window?

"It depends on the infant. Typically the first three months of life are the highest risk, but a lot of that drops because they've had their first vaccine at two months of age. An unvaccinated infant stays at a very high risk for much longer."

"We tend to see a little bit more whooping cough in the winter, but probably about weekly I've been seeing or hearing of a case of whooping cough. It's out there all the time and tends to ramp up late in the winter. There's definitely been a resurgence. Actually, the low point was around the late 1970's and since then, there's been a steady increase in the number of reported cases."

Dr. Belcher says the vaccine used today can start wearing off in three years.

"That means kids ages 4 to 6 who are getting the vaccine, by the time they're 7, 8, 9, they're more susceptible to disease. By the mid-teens, that starts wearing off again and those teens start baby sitting or having their own kids and then there's another uptick."

Click here for more on whooping cough from the Centers for Disease Control and Prevention.