The Facts

Although it's considered a vaccine-preventable disease, whooping cough (pertussis) certainly hasn't been eliminated as a public health problem. The incidence of whooping cough has decreased by more than 97% since the pertussis vaccine was first introduced in the 1940s, but there are still outbreaks.

While most other diseases that are vaccinated against in childhood are decreasing in frequency, cases of whooping cough have actually increased since 1990. This is likely due to the lower effectiveness of older vaccines, decreased protection from the disease (immunity) in adults and adolescents, and increased reporting of whooping cough by doctors.

About 10,000 to 25,000 cases a year have been reported in the United States over the last several years. In the United States, 10 to 20 Americans die each year from whooping cough. Most cases occur in unvaccinated populations. Because the effects of the vaccination wear off, adults are also susceptible to the disease.

Causes

Whooping cough is caused by the bacterium Bordetella pertussis. The bacterium is transmitted in tiny droplets that come from the nose and mouth and is spread from person to person. A similar bacterium called Bordetella parapertussis causes a milder version of whooping cough known as parapertussis.

While most cases of pertussis occur in children under 5 years, it may be that the majority of carriers are older. It's now believed that adults are a major source of infection to infants.

Since many people reach adulthood without having been infected, it's entirely possible for adults to develop whooping cough. After infants, the people most likely to suffer serious complications from whooping cough are seniors and those with chronic ill health.

The disease takes 1 or 2 weeks to incubate. People become infectious to others by the end of the first week and they typically remain contagious for about 6 weeks. The disease is highly contagious and you will be advised to avoid contact with others while you are still able to infect people.