Infants most likely to catch whooping cough from siblings

By Andrew M. Seaman

(Reuters Health) - Infants are now most likely to catch whooping cough from their siblings, a new study says.

"Knowing where they're getting their disease from is important so we can target our approach accordingly," said lead author Tami Skoff, of the Centers for Disease Control and Prevention (CDC) in Atlanta.

In the past, mothers were thought to be the most common sources of the infection for infants.

For the new study, the researchers used data collected between 2006 and 2013 from 1,306 infants in seven states. About a quarter were younger than two months.

By asking who else had whooping cough roughly one to three weeks before the infant's cough began, the researchers were able to identify the source of the infection in 44 percent of cases - and in those cases, it was an immediate family member two thirds of the time.

Siblings were the source of infection in 36% of cases, while mothers were the source in 21% and fathers in 10% of cases.

Mothers were the main source of infection for infants until about 2008, according the researchers. Then, the main source became brothers and sisters.

The researchers wrote September 7 in Pediatrics that the change isn't surprising, because whooping cough is becoming common in older children, in part because protection from the newer versions of the whooping cough vaccine wanes over time.

So, "it makes sense that we're seeing this transition from mothers to siblings as the source of infection," Skoff told Reuters Health.

She also said the research suggests that "cocooning," which is when people around the infant are vaccinated, is likely not effective - especially since her team could find a source of infection less than half the time.

Instead, she said, women should receive the whooping cough vaccine during each pregnancy to pass antibodies to the fetus, and those antibodies can protect the child until he or she is old enough to be vaccinated.

"There are some data out of the UK showing that vaccination during pregnancy is effective," she said. "The early data is very reassuring and promising, which is why we're pushing this strategy."

SOURCE: http://bit.ly/1g5CTzV

Pediatrics 2015.

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