Science & Technology in Action

Introduction 
Pertussis is a serious and very contagious disease which can last for up to three months. It only affects humans and can occur at any age, although children are most commonly affected. 

Pertussis is commonly known as ‘whooping cough’ because it typically gives rise to severe bouts of prolonged coughing followed by a distinctive high-pitched ‘whoop’ sound. 

The disease is more serious in children as they often have difficulty breathing, especially after a bout of coughing, and may turn a blue colour due to lack of oxygen. More than 20% of children with pertussis may require hospitalisation and up to 50% in the case of babies under six months of age. 

Cause and spread of the disease 
Pertussis is caused by Bordetella pertussis, a Gram-negative, aerobic coccobacillus and does not have obvious means of locomotion. It typically lives in the mouth, nose, throat and trachea and sometimes in the lungs. Special cells in these airways produce mucus which traps dust and other airborne particles. The cells lining the trachea have tiny hair-like projections (called cilia) which move mucus upwards to the throat. 

Pertussis bacteria produce toxins that stick to the cilia and prevent them from working properly. This induces a coughing response which is only partially effective in clearing the mucus from the trachea. 

The bacteria are spread from person to person by coughing and sneezing. 

Although most adolescents and adults develop only mild disease similar to a common cold they can still spread the disease to others. 

Pertussis is very contagious and will develop in 90% of unvaccinated children living with someone with pertussis, and in 50% to 80% of unvaccinated children who attend pre-school or school with someone with pertussis.