Pertussis is a contagious disease that has reappeared in the recent years as a public health problem in our country. The clinical presentation has changed especially in the main risk group, children under one year old, evolving in occasions to a highly lethal course called malignant or severe Pertussis. The present review discusses the epidemiology and the mechanisms of pathogenicity, and also describes the risk factors, clinical features and pathophysiology of this particular form. The current evidence and effectiveness of new treatments are described, and a treatment algorithm is proposed.