It is transmitted by direct contact with discharges from respiratory mucous membranes of infected persons by the airborne route. It causes a severe cough of several weeks duration with a characteristic whoop, often with cyanosis and vomiting. In young infants, the cough may be absent and disease may manifest with spells of apnoea. Although pertussis may occur at any age, most cases of serious disease and the majority of fatalities are observed in early infancy.
Vaccines are the most rational approach to pertussis control.
Before the world-wide introduction of pertussis vaccine into the routine childhood vaccination programmes, pertussis was of considerable public health concern in developed as well as in developing countries. Due to the highly contagious nature of this disease, there is always a large number of secondary cases among non-immune contacts. Although prophylactic antibiotic treatment in the early incubation period may prevent disease, the difficulty of early diagnosis, the costs involved as well as the inherent ecological concerns related to induction of drug resistance limit prophylactic treatment to selected individual cases. There are indications that protective immunity to pertussis may wane. A high susceptibility among adolescents and adults may result from both waning immunity following vaccination and a reduced boosting effect from exposure to natural infection.