Malignant pertussis in infants: 4 new cases in French Guiana.

Malignant pertussis is a severe form of pertussis characterized by respiratory distress, polyvisceral failure, and marked hyperlymphocytosis. It typically presents with profound leukocytosis, pulmonary hypertension, and respiratory failure. We report four cases of malignant pertussis in young infants. One patient underwent exchange transfusion. The case fatality rate was 50 %. Preventing these severe and often fatal cases-associated with high mortality and significant intensive care costs-relies primarily on vaccination. Immunization should be ensured for all infants and extended to adults at risk of transmitting the infection to unimmunized infants.