World Health Matters – Denmark: Pertussis linked to small increase in epilepsy

by Gary Finnegan: Researchers in Denmark have found a small but significant increase in the risk of developing epilepsy among children who had hospital-diagnosed pertussis infections. While the absolute risk is low, it is the first time the two diseases have been linked in this way.

As pertussis, commonly known as whooping cough, is a vaccine-preventable disease, the study raises the question of whether the prevalence of epilepsy could be curbed by controlling indirectly through immunisation.

Published in JAMA, a respected medical journal, the study is based on data from registries covering all Danish hospital patients with pertussis born between 1978 and 2011. A database was used to identify 10 individuals from the general population for each patient with pertussis, matched for sex and year of birth.

Dr Morten Olsen, Aarhus University Hospital in Denmark, identified 4,700 patients with pertussis of whom 53 percent were diagnosed before 6 months of age. The cumulative incidence of epilepsy at age 10 years was 1.7 percent for patients in the pertussis cohort and 0.9 percent for members of the comparison cohort. Patients older than 3 years when diagnosed with pertussis were not at increased risk of epilepsy compared with the general population.

The authors write that potential mechanisms underlying the observed association include hypoxic brain damage from coughing, perhaps via increased intrathoracic and intra-abdominal pressure and central nervous system haemorrhages.

Pertussis, an acute respiratory tract infection, is among the most common vaccine-preventable childhood diseases in developed countries. During the acute phase, pertussis is associated with seizures in infants, but the likelihood of developing epilepsy had not been known.