What is Pertussis (Whooping Cough)?

Pertussis, also known as “whooping cough,” is a severe type of cough that could last up to 100 days. The first recorded outbreak of this disease was in Paris in 1578. The bacterium that causes Pertussis, known as Bordetella pertussis, was identified in 1906. By the 1940s, a vaccine was created to protect against the disease. Before this vaccine was made, pertussis was a significant cause of sickness and death in infants. Despite the existence of the vaccine, pertussis remains a severe illness that can lead to high rates of sickness and death.

What Causes Pertussis (Whooping Cough)?

Pertussis, also known as whooping cough, is caused by bacteria called Bordetella pertussis and Bordetella parapertussis. These bacteria spread through the air when someone infected coughs or sneezes. The disease is very contagious. For instance, nearly every person in a household that’s not been vaccinated could get the disease if someone in that household has it. The strength of the vaccination reduces to about half its initial effectiveness after 12 years of taking it.

People with weak immune systems are susceptible to a kind of these bacteria known as Bordetella bronchiseptica, which usually affects animals and is commonly referred to as “kennel cough”.

Humans are the only sources (reservoirs) for the Bordetella bacteria. This bacteria is mainly spread through airborne droplets released during a cough. The bacteria are very contagious and cases usually peak during summer.

There are certain factors that increase the risk of catching pertussis, such as:

* Being pregnant
* Being exposed in an area with a current outbreak
* Not being vaccinated
* Being in close contact with a person who has the disease.

Risk Factors and Frequency for Pertussis (Whooping Cough)

The number of reported cases of pertussis, also known as whooping cough, is on the rise both in the United States and around the world. In the past, before vaccinations for pertussis were available, the US would see between 150,000 and 250,000 cases each year. This number dropped significantly to just 1010 cases reported in 1976 after vaccinations were introduced. However, these numbers have started to rise again, mainly because immunity to the disease in teenagers and adults doesn’t last forever.

Even though pertussis is mostly seen in children, with 38% of cases in babies under 6 months and 71% in children under 5 years, teenagers and adults can also get the disease. In fact, they may be part of the reason we’re seeing more reported cases in all age groups. Across the globe, there are over 24 million cases of pertussis each year, leading to more than 160,000 deaths. In the US, the Centers for Disease Control and Prevention (CDC) reported over 48,000 cases in 2012, the most recent year for which data is available. However, the actual number could be higher due to underreporting and difficulty in diagnosing the disease.

Pertussis is increasingly reported in the USA and globally.
There was a significant decline in cases post-vaccination but numbers have recently begun to increase, mostly due to waning immunity in adolescents and adults.
Pertussis primarily affects children, but adolescents and adults can also contract the disease.
Worldwide, there are over 24 million cases and more than 160,000 deaths annually.
The CDC reported over 48,000 cases in the US in 2012, but the actual figure could be higher due to challenges in diagnosis.

Signs and Symptoms of Pertussis (Whooping Cough)

Pertussis, also known as whooping cough, usually develops over a period of one to three weeks. Following this incubation period, the infection tends to go through three distinct stages: the catarrhal phase, the paroxysmal phase, and the convalescent phase.

The first stage, catarrhal phase, often looks like any other upper respiratory tract infection. Symptoms can include fever, tiredness, runny nose, and redness in the eyes. This stage typically lasts one to two weeks and is when the disease is most contagious.

Then comes the paroxysmal phase. At this stage, the individual experiences bouts of a rapid cough followed by a sharp, high-pitched intake of breath — the “whoop”. These coughing fits can be triggered by cold or loud noises and are often worse at night. While coughing, the individual might turn blue (cyanosis), sweat profusely (diaphoresis) or even stop breathing temporarily (apnea). Immediately after a bout of coughing, the person may vomit or faint, or have another bout of apnea. Even though these symptoms sound severe, individuals often appear to be in good health when they’re not coughing.

In the final convalescent phase, a nagging cough can linger for weeks or even months. This coughing is usually set off when the person gets another respiratory infection or comes into contact with an irritant.

Fever
Tiredness
Runny nose
Redness in the eyes
Rapid coughing followed by a “whoop”
Coughing fits triggered by cold or loud noises
Cyanosis (Blue appearance due to lack of oxygen)
Diaphoresis (Excessive sweating)
Temporary cessation of breathing (Apnea) during coughing
Nagging cough that lingers for weeks to months

It’s important to note that babies and infants might not exhibit typical symptoms like fever. Instead, they might show symptoms like panting, stopping breathing temporarily, becoming blue, and experiencing irregular heartbeat. More severe signs of the disease in infants can also include tiny, red spots above the nipple line due to increased pressure during coughing, nosebleeds, and red eyes due to blood leakage. While listening to their breathing, doctors might find that the sound changes from clear lung sounds to rhonchi, or rattling sounds, which could indicate pneumonia. The identifiable “whooping” sound is usually heard in the children between the ages of six months and five years.

Testing for Pertussis (Whooping Cough)

In an emergency department setup, it’s not very easy to test for pertussis, also known as whooping cough. To diagnose this bacterium-caused illness, health professionals may use a nasopharyngeal culture or a laboratory method called polymerase chain reaction. However, these tests involve extracting and growing the alarming Bordetella organisms, which are hard to cultivate and grow slowly. Culture test results typically take about 3 to 7 days to show up.

Now, here’s a significant point: by the time medical experts start suspecting pertussis in adults, standard culture tests usually don’t detect the bacterium (in 96% of cases). And these culture tests are only able to identify the bacteria in 20% to 40% of cases. Polymerase chain reaction tests are more accurate, but unfortunately, they’re not usually available.

When you walk into an emergency department with a long-lasting cough that comes in sudden, violent episodes (paroxysms) or with a whooping sound or vomiting after severe coughs, doctors might think it could be pertussis. There might also be a high count of white blood cells, especially during the late stages of the bacterial infection and the early stages of severe, spasmodic coughing. In fact, researchers found that the white blood cell count was significantly higher in babies younger than 120 days who sadly passed away compared to those who survived.

To add, the chest x-ray findings for pertussis patients are vague and can show thickening around the bronchi (main air passages), collapsed lung sections (atelectasis), or patches in the lungs that indicate the presence of diseases (infiltrates). One rare, but classic symptom is an indistinct or “shaggy” appearance of the right side of the heart on the x-ray.

Treatment Options for Pertussis (Whooping Cough)

The treatment of whooping cough, or pertussis, is mainly about giving comfort and support to the patient. This can include providing extra oxygen, hydration, and making sure the patient avoids things that can make their breathing worse. If the disease is severe and prolonged, patients might need to get their nutrition through an injection, as eating and drinking can be difficult.

When patients also have conditions like pneumonia, reduced oxygen levels, complications affecting the brain, or are unable to eat and drink, they would need to be cared for in the hospital. Newborn babies and children under one-year-old who haven’t been fully vaccinated are most at risk of suffering from serious health issues related to whooping cough and should be hospitalized no matter their symptoms. Newborns should usually be cared for in intensive care units due to the risk of serious issues involving the heart and lungs, which could happen unexpectedly.

Antibiotics are used to treat whooping cough. Unfortunately, these medicines might not reduce the duration or severity of the disease significantly, especially if started later during illness. The key aim of antibiotics is limiting the spread of the disease. Traditional treatments include erythromycin, azithromycin, and clarithromycin. For patients allergic to these antibiotics, Trimethoprim-sulfamethoxazole can be used. But its effectiveness is not yet proven.

Newborns less than 4 weeks old are typically not given these specific antibiotics due to the risk of a serious condition affecting their stomach called Infantile hypertrophic pyloric stenosis. When a patient is infectious, it’s essential to keep them away from others to prevent the spread of the disease. Whooping cough can be passed on throughout the early stages and for 3 weeks after severe coughing starts. If the patient is treated with antibiotics, they should still be kept in isolation for at least 5 days after starting the treatment. Erythromycin can be used as post-exposure treatment for people living in the same house as the patient.

Corticosteroids, used to reduce inflammation, are sometimes given to very ill infants though they aren’t proven to reduce the disease’s severity. Other treatments like beta2-agonists (medicines that open the airways in the lungs), pertussis immune globulin (blood product with antibodies against pertussis), cough suppressants, and antihistamines (medicines that treat allergy symptoms) are not effective. Rarely, a procedure called exchange blood transfusion may be used to treat a high white blood cells count.

People who have been in close contact with the patient should also be treated with azithromycin or erythromycin. Vaccination is recommended at specific ages in childhood, and adults should also get a single dose of the vaccine to prevent the spread to children. Side effects of the vaccine may include crying and seizures caused by fever, but severe brain-related effects are rare. The vaccine is safe for pregnant women in their third trimester to protect newborns from pertussis.

Pertussis, otherwise known as whooping cough, often starts out looking just like any other common chest infection. This means it can be confused with things like:

Upper respiratory infection (usually caused by a virus)
Bronchiolitis (an infection in the lungs)
Pneumonia (another type of lung infection)
Tuberculosis (a serious infectious disease that affects the lungs).

However, pertussis usually develops in a specific way, progressing through three distinct phases, and it often involves a long-lasting cough without a fever. Because of these unique aspects, it can be differentiated from other lung infections.

In younger individuals, the patient might have accidentally inhaled a small foreign object, leading to similar symptoms. In older people, especially those with a history of certain other health problems, these symptoms could be related to flare-ups of a chronic lung disease known as COPD.

Oddly enough, pertussis can also result in an abnormally high white blood cell count, which might be mistaken for a type of cancer called leukemia.

What to expect with Pertussis (Whooping Cough)

Most individuals who contract the pertussis disease, commonly known as whooping cough, eventually get better. However, the illness usually lasts for several months. The two age groups most affected by this disease are babies and older adults.

Babies face the most serious risk, with about 2% of infants who get the disease not surviving, and this group accounts for 96% of deaths caused by whooping cough. Older adults are more likely to experience severe symptoms from the disease. This could be due to existing chronic health conditions, which may become worse during the illness. They also have a higher chance of experiencing complications like pneumonia.

In some cases, patients may also suffer from secondary complications of whooping cough. These can include pneumonia (an infection that inflames air sacs in one or both lungs), seizures (a sudden, uncontrolled disturbance in the brain), and encephalopathy (a term for any disease of the brain that alters brain function or structure).

Possible Complications When Diagnosed with Pertussis (Whooping Cough)

Pneumonia or an ear infection might follow a disease. Pneumonia is a significant cause of death in infants and young children, usually caused by the aspiration of gastric contents during bouts of coughing or a decreased ability to clear respiratory pathogens. Typically, fever should subside during the initial phase of the disease, and the presence of fever during the paroxysmal phase might suggest pneumonia. Pneumonia is commonly caused by the bacteria Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, and Staphylococcus aureus. It can also be caused by viral infections including respiratory syncytial, cytomegalovirus, and adenovirus.

Central nervous system complications like seizures and encephalopathy may occur in rare cases (less than 2%). These complications could result from a lack of oxygen to the brain, low blood sugar, toxins, secondary infections, or brain bleeding due to increased pressure during coughing. Sudden increases in pressures within the chest and abdomen may lead to swelling around the eyes, collapsed lung, air between lungs and the chest wall, rupture of the diaphragm, hernias in the abdominal and groin area, and rectal prolapse. The pertussis toxin can also trigger histamine hypersensitivity and increased insulin secretion. Infants are especially susceptible to slow heart rate, low blood pressure, and cardiac arrest due to the disease. The emergence of high blood pressure in the lungs has been identified as a factor leading to infantile mortality, as it may cause worsening of systemic low blood pressure and lack of oxygen.

Common Complications:

Pneumonia
Ear Infection
Seizures
Encephalopathy
Swelling around the eyes
Collapsed lung
Rupture of the diaphragm
Abdominal and groin hernias
Rectal prolapse
Slow heart rate
Low blood pressure
Cardiac arrest
Increased insulin secretion
High blood pressure in the lungs

Preventing Pertussis (Whooping Cough)

There are two versions of the vaccine used to protect against whooping cough (or pertussis): a ‘whole-cell’ version and an ‘acellular’ version. Since 1991, the acellular version has largely taken over from the whole-cell version. This is because the whole-cell version was linked to severe side effects like immediate but temporary brain disease and long-lasting seizures. The newer acellular version has fewer side effects and works just as well to prevent whooping cough.

Nowadays, doctors only recommend the old version if the acellular vaccine is not available for some reason. Typical side effects of the acellular vaccine are generally mild and may include a low-grade fever, irritability, changes in behavior, and pain where the shot was given. In rare cases, more severe reactions may include a high fever above 40 C (104 F), persistent high-pitched crying, and seizures.

The safety of the acellular pertussis vaccine was confirmed in a large study involving over 50,000 patients who received the vaccine between 1981 and 2016. The study found no new or unexpected side effects, further reassuring the safety of this vaccine.