Pertussis, also known as whooping cough, is a highly contagious respiratory tract infection characterized by cough fits (paroxysmal cough). It is most commonly caused by the bacterium Bordetella pertussis, though Bordetella parapertussis has also been associated with this condition in humans.
Pertussis remains a significant cause of morbidity and mortality in infants younger than 1 year. It is known for uncontrollable, violent coughing which often makes it hard to breathe and can affect people of all ages. The coughing may last for 10 or more weeks, hence the phrase "100-day cough." In China, pertussis is known as the “100 day cough.”
After cough fits, a high-pitched “whoop” sound or gasp may occur as the person needs to take deep breaths, hence the common name of “whooping cough”. A person may cough so hard that they vomit, break ribs, or become very tired from the effort.
Causes and Transmission
Commonly caused by Bordetella pertussis, a type of bacteria that lives in the mouth, nose and throat. These bacteria thrive in the respiratory passages where they attach to the cilia (tiny, hair-like extensions) and produce toxins (poisons) which damage these cilia that are needed to remove particulate matter and cellular debris that are normally introduced into the airways with each breath. This results in an increased inflammation of the respiratory passages and the typical dry cough which is the hallmark of the infection.
Pertussis is a very contagious disease only found in humans. It is an airborne disease which spreads easily from person to person through breathing in the bacteria that are present in droplets released when an infected person coughs or sneezes, or when spending a lot of time near an infected person where you share breathing space. Many babies who get pertussis are infected by older siblings, parents, or caregivers who might not even know they have the disease.
Sharing food, drinks or cigarettes, or kissing someone who has the pertussis bacteria can also put one at risk.
People are infectious from the start of symptoms until about three weeks into the coughing fits. Those treated with antibiotics are no longer contagious after five days.
Signs and Symptoms
Symptoms usually develop within 5 to 10 days after one is exposed. Sometimes pertussis symptoms do not develop for as long as 3 weeks.
The first stage of pertussis is the catarrhal stage. In the catarrhal stage, which typically lasts for one to two weeks, an infected person has cold-like symptoms (characteristic of an upper respiratory infection), including
red, watery eyes,
low-grade fever (generally minimal throughout the course of the disease),
apnoea – a pause in breathing (in babies) and
mild, occasional cough, similar to the common cold.
It is important to note that particularly during this early phase of infection, individuals may believe they have a common cold and may not be aware that they have pertussis.
After 1 to 2 weeks and as the disease progresses, the cough gradually becomes more severe, the second stage begins. It is during this second stage that physicians suspect a diagnosis of whooping cough. The following characteristics describe the second stage:
Paroxysms (fits) of many and rapid coughs followed by a high-pitched “whoop” sound.
Paroxysmal attacks occur more frequently at night, with an average of 15-24 attacks per 24 hours.
Vomiting (throwing up) during or after coughing fits.
During an attack, the individual may become cyanotic (skin and mucous membranes may turn blue) from lack of oxygen.
Exhaustion (very tired) after coughing fits.
This stage known as the paroxysmal stage usually lasts from one to six weeks but may persist for up to 10 weeks.
The third stage of whooping cough is the recovery or convalescent stage. In the convalescent stage, recovery is gradual. The cough becomes less paroxysmal and usually disappears over two to three weeks; however, paroxysms often recur with subsequent respiratory infections for many months.
Though, most people with whooping cough have coughing spells, but not everyone does. Infants may not have the strength to make the whooping sound or even cough, but they might gasp for air or try to catch their breath during these spells.
In those who have gotten the pertussis vaccine:
In most cases, the cough won’t last as many days.
Coughing fits, whooping, and vomiting after coughing fits occur less often.
The percentage of children with apnoea (long pause in breathing), cyanosis (blue/purplish skin coloration due to lack of oxygen) and vomiting is less.
Babies and Children
Pertussis (whooping cough) can cause serious and sometimes deadly complications in babies and young children, especially those who have not received all recommended pertussis vaccines.
About half of babies younger than 1 year old who get pertussis need care in the hospital. The younger the baby, the more likely they will need treatment in the hospital. Of those babies who are treated in the hospital with pertussis about:
1 out of 4 (23%) get pneumonia (lung infection)
1 out of 100 (1.1%) will have convulsions (violent, uncontrolled shaking)
3 out of 5 (61%) will have apnoea (slowed or stopped breathing)
1 out of 300 (0.3%) will have encephalopathy (disease of the brain)
1 out of 100 (1%) will die
Teens and Adults
Teens and adults can also get complications from pertussis. They are usually less serious in this older age group, especially in those who have been vaccinated with a pertussis vaccine. The cough itself often causes complications in teens and adults. For example, you may pass out or break (fracture) a rib during violent coughing fits.
In one study, less than 1 out of 20 (5%) teens and adults with pertussis needed care in the hospital. Healthcare professionals diagnosed pneumonia (lung infection) in 1 out of 50 (2%) of those patients. The most common complications in another study were:
Weight loss in 1 out of 3 (33%) adults
Loss of bladder control in 1 out of 3 (28%) adults
Passing out in 3 out of 50 (6%) adults
Rib fractures from severe coughing in 1 out of 25 (4%) adults
Healthcare providers diagnose whooping cough by considering if you have been exposed to pertussis and by doing a:
History of typical signs and symptoms
Laboratory test which involves taking a sample of mucus (with a swab or syringe filled with saline) from the back of the throat through the nose
Many infants and some young children will need to be hospitalized during treatment, for observation and respiratory support. Some may need intravenous (IV) fluids for dehydration if symptoms prevent them from drinking enough fluids.
Healthcare providers generally treat pertussis with antibiotics and early treatment is very important. Treatment may make your infection less serious if you start it early, before coughing fits begin. Treatment can also help prevent spreading the disease to close contacts (people who have spent a lot of time around the infected person). Treatment after three weeks of illness is unlikely to help because the bacteria are gone from your body by then, even though you usually will still have symptoms. This is because the bacteria have already done damage to your body.
There are several antibiotics available to treat pertussis. If a healthcare professional diagnoses you or your child with pertussis, they will explain how to treat the infection.
Pertussis can sometimes be very serious, requiring treatment in the hospital. Babies are at greatest risk for serious complications from pertussis.
Do not give cough medications unless instructed by your doctor. Giving cough medicine probably will not help and is often not recommended for kids younger than 4 years old.
Manage pertussis and reduce the risk of spreading it to others by:
Following the schedule for giving antibiotics exactly as the doctor prescribed.
Keeping your home free from irritants that can trigger coughing, such as smoke, dust, and chemical fumes.
Using a clean, cool mist vaporiser to help loosen mucus and soothe the cough.
Practicing good handwashing.
Get plenty of rest. A cool, quiet and dark bedroom may help you relax and rest better.
Stay quiet and calm to help prevent coughing.
Drink plenty of fluids, including water, juices, and soups, and eating fruits to prevent dehydration. If your coughing spells are so bad that they keep you from drinking enough fluids, you risk dehydration. Call your doctor right away. Also, report any signs of dehydration immediately, which include dry-sticky mouth (dry lips and tongue), dry skin, sleepiness or tiredness, or thirst. They also include decreased urination or fewer wet diapers (for kids), few or no tears when crying, muscle weakness, headache, dizziness or lightheadedness.
Eat small meals every few hours to help prevent vomiting (throwing up) from occurring.
Recovery from pertussis can happen slowly. The cough becomes milder and less common. However, coughing fits can return with other respiratory infections for many months after the pertussis infection started.
Also, while most healthy older children and adults fully recover, infection in newborns is particularly severe.
The best way to protect against whooping cough is by getting vaccinated.
While pertussis vaccines are the most effective tool to prevent this disease, no vaccine is 100% effective. When pertussis circulates in the community, there is a chance that a fully vaccinated person, of any age, can catch this disease. If you have gotten the pertussis vaccine but still get sick, the infection is usually not as bad. Also, keep babies and other people at high risk for pertussis complications away from infected people.
If you or a member of your household has been diagnosed with pertussis, your doctor or local health department may recommend preventive antibiotics (medications that can help prevent diseases caused by bacteria) to other members of the household to help prevent the spread of disease. Additionally, they may recommend preventive antibiotics to some other people outside the household who have been exposed to a person with pertussis, including
People at risk for serious disease
People who have routine contact with someone that is considered at high risk of serious disease
Like many respiratory illnesses, pertussis spreads by coughing and sneezing while in close contact with others, who then breathe in the bacteria. It is recommended to practise good hygiene to prevent the spread of respiratory illnesses. To practise good hygiene you should:
Cover your mouth and nose with a tissue when you cough or sneeze.
Put your used tissue in the waste basket.
Cough or sneeze into your upper sleeve or elbow, not your hands, if you don’t have a tissue.
Wash your hands often with soap and water for at least 20 seconds.
Use an alcohol-based hand rub if soap and water are not available.