Whooping Cough
(Pertussis)
In this condition factsheet:
The Facts on Whooping Cough
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 90% over the last 70 years, 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 (due to the emergence of new strains of the bacteria that causes the disease), decreased protection from the disease (immunity) in adults and adolescents as the effect of the vaccine wears off, parents opting out of vaccinating their children, and increased reporting of whooping cough by doctors.
Between 1,000 and 3,000 people each year get sick from pertussis. In Canada, 1 to 4 Canadians die each year from whooping cough. In unvaccinated populations, most cases occur in children under 5, especially in babies less than 6 months old. Because the effects of the vaccination wear off, adults are also susceptible to the disease. Those who have had the disease in the past may get it again, but it is usually a mild form which may go unrecognized and undiagnosed.
Causes of Whooping Cough
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. It is recommended for all pregnant women to receive a pertussis vaccination in their third trimester of pregnancy. It's important for people in regular contact with infants to be immunized. Anyone who needs a booster vaccine, should receive it 2 weeks before coming into contact with a newborn baby.
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.
Symptoms and Complications of Whooping Cough
The disease has 3 stages. The first stage begins about 10 days after infection and causes symptoms like a common cold – sneezing, watery eyes, tiredness, and loss of appetite. There's also a dry hacking cough.
The second stage occurs after 10 to 14 days and is signalled by a rapid increase in the frequency and severity of coughing. It's this cough that gives the disease its name. Half a dozen or more rapid coughs follow each other in quick succession, followed by a "whooping" sound as the person inhales deep and fast. It may happen hundreds of times in a single day. The coughing may produce large amounts of thick mucus. Sometimes infants swallow it, but it may exit through the nostrils, often forming bubbles. Frequent coughing and mucus can cause vomiting, and choking is a risk in infants. Infants are actually less likely to make the whooping sound than are older children, but they're more likely to have a choking spell. Infected adults rarely whoop – they just cough frequently and spasmodically.
After a month, most people start to look and feel better and cough less. This is the third stage - a gradual recovery taking a few weeks or occasionally a few months. The usual total course of the disease lasts 6 to 10 weeks, but coughing may come and go for months.
The risk of complications is highest in infants under one year old. There's also potential danger to seniors and those with chronic ill health. Complications include pneumonia, encephalitis (inflammation of the brain), seizures, apnea (brief periods when breathing stops), and hemorrhages (bleeding) in the eye.
