Whooping cough in infancy is associated with an increased risk for epilepsy, a study has found.

The findings underscore the importance of vaccination for whooping cough, also known as pertussis, in childhood. Danish researchers used government registries to find 4,700 children born from 1978 to 2011 who received diagnoses of whooping cough; about half were found to have the disease when they were less than six months old.

Each child was matched with 10 healthy control individuals from the general population. Among the 4,700 children who had pertussis, 1.7 per cent later developed epilepsy, compared with 0.9 per cent among the 47,000 control people.

After adjusting for gestational age, congenital malformations, a maternal history of epilepsy and other health variables, the researchers calculated that the risk of developing epilepsy by age 10 in a child who had had whooping cough was 70 per cent higher than for an uninfected child.

The study was published in The Journal of the American Medical Association. “We can’t say that if a child has epilepsy it was because of a pertussis infection,” said the lead author, Dr Morten Olsen, an associate professor in the department of clinical epidemiology at Aarhus University Hospital in Denmark.

“And in any case, the absolute risk for epilepsy is very small — about 2 in 100. So we don’t want anyone to panic.”

But, he said, “this is another argument to have your child vaccinated.” Pertussis is known to be associated with seizures and brain damage, but this is the first study to find an association with epilepsy.