Pertussis – also known as whooping cough or 100-day cough – is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. The disease is airborne and spreads rapidly via the coughs and sneezes of infected people.

The classic symptoms of pertussis are paroxysmal cough with inspiratory whoop, fainting or vomiting after coughing. The cough from severe pertussis can cause subconjunctival haermorrhages, rib fractures, urinary incontinence, hernias and vertebral artery dissection. The coughing may last for ten or more weeks.

In 2015, an estimated 16.3 million people worldwide were infected by pertussis of which 58,700 died – primarily very young children and people with weakened immune systems from developing countries. This is a considerable improvement from 1990 where 138,000 people died from the disease.

Outbreaks of pertussis have been described since the 16th century. The bacteria that causes the infection (Bordetella pertussis) was discovered in 1906, and in 1924 the first vaccine was developed. Since 1961 it has been part of the Danish child vaccine program. Before the vaccine program, three out of four Danish children suffered severe pertussis attacks, and an average often children died of the disease each year. Now, due to the effective vaccine program, serious pertussis is very rarely seen in Denmark.