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Column originally published Jan 2, 2001
Column last revised/updated on Sep 11, 2018

It Is Important To Test And Treat Whooping Cough Early

Question: My brother and his family live next door. Their two children have asthma and they cough almost daily. Lately their cough is just wicked. Yesterday their doctor suspected they have whooping cough, and sent them for tests. These children play with our boys every day after school. Our two boys have just started coughing, although they don’t have a cold or asthma. I am really worried that they might have caught this whooping cough. What can I do?


Whooping cough is a serious infection in children, caused by the small bacteria Bordetella pertussis. Infection is passed from one person to another through droplet secretions when a person coughs. These bacteria multiply in the back of the nose and throat. The time it takes from infection until the first symptoms (also called incubation period) is between one to three weeks.

At the beginning of the illness, the symptoms are very similar to common cold, with a little stuffy nose, sore throat, and some cough. Fever is usually not serious. This early stage can last one to two weeks.

The next stage is called paroxysmal phase, when the cough becomes much more severe, especially in young children who did not receive the full series of whooping cough vaccine. The cough comes in spasms, with several coughs one after the other, often to the point of losing the breath. The face would turn red, sometimes even dusky. The eyes would water, and many children gag on the mucus and vomit. At the end of a cough spasm, one may hear a “whoop” sound while the child breathes in. This “whoop” is the reason for the name whooping cough.

In some children, especially the very young ones, vomiting can be a serious problem. It can cause dehydration and weight loss. In the years before vaccination and effective treatment, some young infants died as a result of dehydration, malnutrition, or brain haemorrhage. Some develop serious brain damage from lack of oxygen as a result of prolonged cough spasms.

These cough spasms can last several weeks. Gradually the cough spasms would ease off, with shorter and less severe spasms. The whole illness can last several months. In the Chinese language, whooping cough is called “one-hundred-day cough.” This will give you some idea of the seriousness and chronicity of this illness.

What I have described so far is the “typical” whooping cough, which is seen most often in children. In adolescents and adults, they often develop bad, prolonged cough, but not to the point of severe cough spasms. As a result, whooping cough in these individuals is often missed or misdiagnosed.

In the last few decades, whooping cough has been partially controlled by vaccination beginning at two months of age. This has prevented most young children from developing very serious or fatal illness. However, the last booster shot is given at 6 years of age. The body’s immunity against whooping cough gradually declines afterwards. That is why the bacteria can infect many adolescents and adults, although their symptoms are milder than young children.

What you should do right away is to take your two sons to see your doctor, and explain to him/her about the condition of their cousins. Your doctor likely will order a secretion test (by passing a small plastic tube into the nostril) to find the bacteria.

This secretion test (to recover the whooping cough bacteria by culture) is best done at the beginning of illness, shortly after a person starts to cough. The chance of recovering the bacteria decreases when there is a lot of cough spasms. Furthermore, these bacteria are very fragile and hard to culture. Under the best circumstances, the success rate of culturing them is only about 50%. Even so, it is important to confirm the diagnosis by culture. Most qualified microbiology laboratory is equipped to culture the whooping cough bacteria.

More sensitive tests have been developed, but their use is still restricted to research laboratories. A PCR (polymerase chain reaction) test helps to identify the genetic marker of the bacteria, when too few of them are present to be recovered by culture technique.

Another new test is to detect specific antibodies in the blood directed at the whooping cough bacteria. The body produces these antibodies after infection, in an attempt to fight off the bacteria. Again, this is available only as a research tool at the present time. There may be a laboratory in your region that your doctor can contact to perform these tests when the symptoms are suggestive of whooping cough, but regular culture is negative.

Whooping cough tends to appear in epidemics every 3 to 5 years. I have recently seen and confirmed a number of children with whooping cough, ranging in age from 5 weeks to early teens. I am afraid there will be many more getting sick with whooping cough before this winter is over.

With a history like yours, antibiotics should be started right after secretion test from the nostril is done. The culture takes 5 to 7 days to grow the bacteria. Precious time would be lost if we wait for the culture result. If treatment is delayed, your children will in turn spread the whooping cough bacteria to other children and adults, further increasing the chance of epidemic.

The most effective antibiotic is Erythromycin, given 3 to 4 times a day for 14 days. The most common side effect is stomach pain; therefore this medicine should be taken with food. After taking Erythromycin for 5 days, the person is regarded as not contagious, and is safe to go back to school or to work.

Sometimes the stomach pain from Erythromycin is too severe. If that happens, newer related antibiotics called Clarithromycin and Azithromycin can be used. The recommended course for them is 7 days, although we are not completely certain that this shorter course is just as effective.

Finally, I would like to tell those parents who are worried about the whooping cough vaccine. As I mentioned earlier, the reason that whooping cough is not a widespread disease nowadays is because of the use of vaccine for the last several decades. The new version of the vaccine, called “acellular vaccine,” has much less side effect than previous vaccines that were available.

In England, a group of parents were very concerned about giving their children whooping cough vaccine in the late 1970s and early 1980s. As a result, a significant number of these children were unvaccinated. When an outbreak of whooping cough spread through the country, many children died from this disease. Most of them did not receive the vaccine.

What we have learned is that whooping cough vaccine, although not a perfect one, does give fairly good protection to children, and would prevent them from serious and sometimes fatal whooping cough infection.

[Note to Readers: Most of the information here is still accurate. We don’t culture whooping cough bacteria any more, because PCR test is more sensitive, more accurate, and much faster. Clarithromycin and Azithromycin are used more frequently than Erythromycin because of less abdominal side effects. The acellular vaccine is now recommended for adults in addition to children.]