How contagious is whopping cough?

Whooping cough, caused by the bacterium Bordetella pertussis, is highly contagious. It spreads primarily through respiratory droplets when an infected person coughs or sneezes. Individuals are most contagious in the early stages of the illness, before the characteristic "whoop" sound develops, and can spread the infection for about two weeks without treatment. Vaccination significantly reduces the risk of contracting and transmitting the disease.