Pertussis vaccine and whooping cough as risk factors in acute neurological illness and death in young children.

The National Childhood Encephalopathy Study received reports on 1182 cases of serious acute neurological illnesses in children admitted to hospital in Britain. The frequency of risk factors in cases was compared with matched controls. A personal or family history of convulsions was found significantly more often in cases than in controls, but no such excess was found for a history of allergy. Case children were significantly more likely to have received diphtheria, tetanus and pertussis (DTP) vaccine within seven days before onset and to have a history of whooping cough during the month of onset. The risk of serious acute brain conditions after the disease was more than six times that of three doses of DTP. In addition, there is evidence that deaths attributed to whooping cough may seriously underestimate the number associated with pertussis infection.