Children Can Get Whooping Cough From Adults
Question: Our teenage son was sick with a bad cough for almost two months. His cough was so severe that he would lose his breath, his whole face turned beef-red, and he would vomit mucus from time to time. As a result, he missed several weeks of school. We took him to our doctor and to emergency room many times, and were told that he just had a bad virus. He has mild asthma, but his inhalers didn’t help him at all. After two months of coughing, he was seen by a paediatrician who suspected whooping cough. By that time, my husband and our two younger sons also started coughing, although they were not nearly as severe. All of them were tested and they were positive for whooping cough. I am really puzzled by this. Our children were all immunized according to the public health schedule. Why could they get infected with this nasty germ, and why is it so difficult to diagnose? Could we have prevented this somehow?
It is unfortunate that your son contracted whooping cough and passed it to the rest of the family. You have raised some important questions here. Before I answer them, let me explain a little more about whooping cough for the benefit of all readers.
Whooping cough, also called pertussis, was first reported in medical literature in the year 1540. The first epidemic was actually recorded in 1578. Widespread epidemic occurred in 17th and 18th centuries, killing many infants and young children. Those who survived developed life-long immunity to the bacteria Bordetella pertussis.
At the beginning of infection, the symptoms of whooping cough is very similar to those of regular colds, making it very difficult to make a definitive diagnosis, until the more typical cough spasms started to appear.
The hallmark of whooping cough is the severe cough spasms, when several to many powerful coughs, one following the other, make it hard for the person to take in a breath. As a result, the person’s face often turns red and sometimes even dusky or purplish. At the end of a cough spasm, air is drawn rapidly into the lungs, and produce the whooping sound that is characteristic of whooping cough. This whoop, however, is not always present, especially in young infants.
This more severe phase of whooping cough can last several weeks. Many young infants, especially those who are not fully immunized, can develop more serious illnesses. With their smaller bronchial tubes, they have difficulty coughing up the mucus. As a result, collapse of the lungs and pneumonia are frequent complications. The severe cough spasms can also lead to bleeding in the face, the eyes, as well as the brain. Many children cannot tolerate feeding because of coughing and vomiting, resulting in dehydration and weight loss. The most serious complication is brain damage and death because of lack of oxygen.
If the child survives this period of severe cough spasms, the coughs gradually decrease in frequency and severity. In the Chinese language, whooping cough is called ‘hundred-day cough.’ This will give you an idea of the lengthy coughing illness that is typical of the disease.
Whooping cough vaccine was first introduced in Canada in the 1940s. It is one of the earliest vaccine available for children. The vaccine was produced by culturing the bacteria in the laboratory. In the manufacturing process, the bacteria were killed so that they cannot cause an infection. This ‘whole cell’ vaccine was effective in inducing immunity in children. The number of cases of whooping cough dropped by more than 70% after the vaccine was used across Canada.
However, this vaccine cannot be given to children over 7 years of age, because it can induce more severe side effects. As a result, over the last few decades, we have a whole society of adults who were vaccinated with whooping cough vaccine during their early childhood years, and were never infected naturally with the Bordetella pertussis bacteria. Their antibody levels gradually decrease over time, so that once again they become susceptible to the bacteria.
In the last ten years, it was recognized increasingly that adolescents and adults are frequently infected with whooping cough. Many of them have prolonged cough, but they do not necessarily develop the typical whooping cough symptoms, therefore making it difficult for physicians to diagnose. Furthermore, we have a generation of doctors who have never seen patients with whooping cough during their training. As a result, there is under-reporting of this disease due to lack of recognition.
These infected teenagers and adults can spread the whooping cough bacteria for several weeks after the infection. When they are in contact with young children who are not fully immunized, these children often develop the full-blown disease, which is more easily recognized. When one traces the source of infection, it is not difficult to find the teenager or adult who brought the infection to the young victim unknowingly.
In 1997, the acellular pertussis vaccine (aP) was introduced into Canada (acellular means without the complete bacterial cell). This vaccine was manufactured by breaking up the bacteria and purifying individual components so that only the important ones are incorporated into the vaccine. This purified vaccine is more effective in inducing immunity in young children and has much less side effects.
Because we know adolescents and adults can carry whooping cough bacteria and infect young children, the next logical step is to find out whether the new vaccine can be used in this group of individuals. Extensive research was conducted in many countries over the last few years. Fortunately, the answer is yes, but a smaller dose is required to reduce side effects.
Recently, the National Advisory Committee on Immunization and the Canadian Paediatric Society have both recommended this ap vaccine for teenagers (ap stands for low dose acellular pertussis vaccine). At the present time, most teenagers in Canada receive the booster diphtheria and tetanus (dT) vaccine between 14-16 years of age. The new dTap (combining diphtheria, tetanus, acellular pertussis) vaccine can be incorporated without changing the vaccination schedule.
Right now, only Newfoundland and Labrador, Nunavut and the Northwest Territories use this new dTap vaccine. We certainly hope that all other provinces across Canada can incorporate this new vaccine to protect teenagers, and ultimately young children, from developing whooping cough. Whether this vaccine should be used more widely by other adults still require additional studies.
I hope you have gained some insight into the difficulty of recognizing whooping cough, and how scientists have tried to reduce the spread of bacteria in adults, teenagers, and young children.
[Note to Readers: This dTap vaccine is now used across the country for adults to boost their immunity against diphtheria, tetanus, and whooping cough.]