Pertussis

What is pertussis?

Pertussis, commonly called whooping cough, is a highly contagious infection of the airways caused by a bacterium named Bordetella pertussis. The infection irritates the lining of the breathing tubes and triggers fits of severe, repeated coughing. The name “whooping cough” comes from the high-pitched “whoop” sound some people make when they gasp for air after a coughing fit, although not everyone with pertussis makes this sound.

When people ask “what is pertussis,” the short answer is that it is a bacterial respiratory infection that spreads easily from person to person through droplets released when someone coughs or sneezes. It can affect people of any age. Infants under one year, and especially babies under six months who have not yet completed their vaccinations, are at the highest risk of serious complications. Older children, teenagers, and adults can also catch pertussis, often with a milder but long-lasting cough, and they may pass the infection to vulnerable babies without realizing it.

Vaccination has greatly reduced the number of pertussis cases worldwide, but the disease has not disappeared. Protection from vaccines or from past infection fades over time, which is why booster doses are recommended and why outbreaks still occur in many countries.

Pertussis symptoms

Pertussis symptoms usually develop in stages over several weeks. Early on, the illness can look like an ordinary cold, which makes it hard to recognize. Common pertussis symptoms include:

• Runny or stuffy nose
• Mild, occasional cough that gradually gets worse
• Low-grade fever or no fever at all
• Fits of rapid, violent coughing (called paroxysms) that are hard to stop
• A high-pitched “whoop” when breathing in after a coughing fit
• Vomiting during or right after coughing
• Exhaustion after coughing episodes
• Difficulty breathing or turning blue around the lips during a fit
• In babies, pauses in breathing (apnea) with little or no cough

Stage one: the catarrhal stage

The first stage typically lasts about one to two weeks. It is often mistaken for a common cold, with a runny nose, mild cough, sneezing, and sometimes a slight fever. People are very contagious during this stage, even though they may not feel especially ill.

Stage two: the paroxysmal stage

In the second stage, the cough becomes much more severe. Coughing fits may occur many times a day and are often worse at night. A fit can last long enough that the person struggles to breathe, and it may end with the characteristic whoop, gagging, or vomiting. Between fits, many people appear relatively well. This stage can last from one to six weeks, and in some cases longer.

Stage three: the convalescent stage

In the recovery stage, the coughing fits gradually become less frequent and less intense. However, the cough can linger for weeks or months, and it may flare up again if the person catches another respiratory infection. Because of this long course, pertussis is sometimes called the “100-day cough.”

How symptoms differ by age

Babies do not always cough in the typical way. Instead, they may have episodes where they stop breathing briefly, become pale or bluish, or seem to gag or struggle. These signs are medical emergencies. Vaccinated older children and adults often have milder symptoms, sometimes just a persistent cough without the whoop, which is why the infection can go unrecognized and continue to spread.

Causes and risk factors

Understanding pertussis causes helps explain why the infection spreads so readily. Pertussis is caused by the bacterium Bordetella pertussis. The bacteria attach to the tiny hair-like structures (cilia) that line the upper airways and release toxins. These toxins damage the cilia and cause the airways to swell, which leads to the intense coughing that is the hallmark of the disease.

The infection spreads through the air when an infected person coughs, sneezes, or breathes close to others. People are most contagious in the early cold-like stage and during the first few weeks of coughing. Without treatment, a person may remain contagious for about three weeks after the coughing fits begin.

Risk factors

Anyone can catch pertussis, but some people are more likely to be infected or to become seriously ill:

• Infants under one year, especially those too young to have completed their primary vaccine series
• Unvaccinated or incompletely vaccinated children and adults
• Fading immunity in teenagers and adults who have not had a booster dose for many years
• Pregnant women, particularly in the last trimester, because of the risk to the newborn
• Close contact with an infected person at home, school, or daycare
• Underlying health conditions such as asthma, chronic lung disease, or a weakened immune system
• Health care and childcare workers who are regularly exposed to respiratory infections

Pertussis diagnosis

A pertussis diagnosis can be challenging, especially in the early stage when symptoms resemble a common cold. Doctors typically combine a detailed medical history, a physical examination, and laboratory tests to confirm the infection.

Medical history and examination

Your doctor will ask how long the cough has lasted, whether it comes in fits, whether there is a whoop or vomiting afterward, and whether you or your child have had contact with anyone who has a prolonged cough. Vaccination history is also important. During the examination, the doctor listens to the lungs and checks for signs of breathing difficulty. Because people with pertussis often appear well between fits, the examination alone may not be enough to confirm the diagnosis.

Laboratory tests

• Nasopharyngeal swab: a soft swab is passed through the nose to the back of the throat to collect mucus. The sample can be tested in two main ways.
• PCR test (polymerase chain reaction): a test that detects the genetic material of the bacteria. It is currently the most commonly used test because results are relatively quick and it works well in the first few weeks of illness.
• Bacterial culture: the sample is grown in a laboratory to see whether Bordetella pertussis develops. Culture is very specific but takes several days and is most reliable early in the illness.
• Blood tests (serology): these measure antibodies, which are proteins the immune system makes in response to infection. Serology may be useful when someone has been coughing for several weeks and swab tests are less likely to be positive.
• Complete blood count: in infants, a very high white blood cell count, particularly of a type called lymphocytes, can support the diagnosis.

Imaging

A chest X-ray is not needed to diagnose pertussis itself, but your doctor may order one if pneumonia (infection deep in the lungs) or another complication is suspected, particularly in infants or in people with breathing difficulty.

Clinical criteria

Public health authorities often define a probable case of pertussis as a cough lasting two weeks or more together with coughing fits, a whoop, vomiting after coughing, or, in infants, pauses in breathing, when there is no other clear explanation. Laboratory confirmation strengthens the diagnosis, but doctors may start treatment based on clinical suspicion alone, especially when a vulnerable baby is involved.

Pertussis treatment options

Pertussis treatment options depend on the person’s age, how long they have been ill, and how severe the symptoms are. Treatment aims to limit the spread of infection, reduce the severity of illness when started early, and manage complications.

Antibiotics

Antibiotics are the main medical treatment for pertussis. Doctors usually prescribe a type of antibiotic known as a macrolide, such as azithromycin, clarithromycin, or erythromycin. An alternative antibiotic may be used for people who cannot take macrolides.

Antibiotics work best when started during the first one to two weeks of illness, before the severe coughing fits begin. At that point they may shorten the illness and reduce its severity. If treatment starts later, antibiotics are less likely to change the course of the cough, because the damage to the airways has already occurred. However, they are still often recommended because they clear the bacteria from the nose and throat and stop the person from infecting others, usually within about five days of starting the course.

Preventive antibiotics for close contacts

Your doctor may recommend antibiotics for people who live with or have had close contact with someone diagnosed with pertussis, even if they have no symptoms. This is known as post-exposure prophylaxis. It is considered particularly important for infants, pregnant women in their third trimester, and people who care for babies.

Supportive care at home

Most older children and adults with pertussis can recover at home. Supportive measures include:

• Getting plenty of rest and drinking enough fluids to prevent dehydration, especially if vomiting occurs after coughing
• Eating small, frequent meals to reduce vomiting during coughing fits
• Keeping the air free of irritants such as tobacco smoke, dust, and strong fumes
• Using a clean cool-mist humidifier, which some people find soothing, although evidence for its benefit is limited
• Practicing good hand hygiene and covering coughs to protect others

Over-the-counter cough medicines are generally not recommended, as they have not been shown to help with pertussis and are not considered safe for young children. Always ask a pharmacist or doctor before giving any medicine to a child.

Hospital care

Infants under six months, and anyone with severe breathing problems, are often admitted to the hospital. In the hospital, treatment may include monitoring of breathing and oxygen levels, oxygen therapy, suctioning of thick mucus from the airways, and fluids given through a vein if the baby cannot feed properly. In the most severe cases, intensive care support, including help with breathing from a machine, may be needed. Hospital staff also isolate the patient to prevent spread to others.

Procedures and surgery

There is no surgical treatment for pertussis. Procedures such as airway suctioning or, rarely, placing a breathing tube are supportive measures used in severe cases rather than treatments for the infection itself.

Rehabilitation

Formal rehabilitation is not usually needed. Recovery involves time for the airways to heal. Your doctor may advise a gradual return to normal activity and may recommend a follow-up visit if the cough is unusually prolonged or if there are concerns about lung function. At Acibadem, pertussis is generally managed by infectious disease, pediatric, and pulmonology departments, depending on the patient’s age and severity of illness.

Living with pertussis and outlook

For most older children, teenagers, and adults, pertussis is an exhausting but ultimately self-limiting illness. The severe coughing fits gradually fade, and the majority of people recover fully without lasting damage to the lungs. The main challenge is the duration: coughing can continue for weeks or months, disturbing sleep and daily activities. Complications in this age group may include rib fractures from forceful coughing, fainting, urinary incontinence, hernias, and, less often, pneumonia.

The outlook is more serious for infants, particularly those under six months. Babies are at risk of pneumonia, seizures, dehydration, brain damage from lack of oxygen, and, in rare cases, death. This is why doctors take a suspected pertussis infection in a baby very seriously and why early treatment and hospital observation are frequently recommended. With modern care, most infants do recover, but the risk of severe illness is real and should not be underestimated.

Having pertussis once does not guarantee lifelong immunity. Protection after infection or vaccination tends to weaken over the years, so a person can catch the disease again later in life, though repeat infections are often milder. For this reason, staying up to date with recommended vaccines remains important even after recovery.

People recovering from pertussis may find it helpful to avoid smoke and other irritants, to keep well hydrated, and to allow extra time for rest. If a new respiratory infection develops during recovery, the coughing fits may temporarily return; this does not necessarily mean the pertussis has come back, but it is reasonable to check with a doctor if you are unsure.

Frequently asked questions

What is pertussis and how is it different from a normal cough?

Pertussis is a bacterial infection of the airways caused by Bordetella pertussis. Unlike a typical cold, which usually improves within about a week or two, pertussis produces fits of severe, repeated coughing that can last for many weeks. The cough often comes in bursts, may end with a whooping sound or vomiting, and tends to be worse at night. A cough that lasts more than two weeks and comes in fits should be evaluated by a doctor.

What are the first pertussis symptoms to look for?

The earliest pertussis symptoms are usually mild and resemble a common cold: runny nose, sneezing, a mild cough, and sometimes a low fever. Over one to two weeks, the cough worsens into intense fits. Because the early stage looks so ordinary, pertussis is often not suspected until the severe coughing begins. In infants, early signs may include feeding difficulty, gagging, or brief pauses in breathing rather than a noticeable cough.

What are the main pertussis causes?

Pertussis is caused by a single bacterium, Bordetella pertussis, which spreads through respiratory droplets when an infected person coughs or sneezes. Toxins released by the bacteria damage the lining of the airways and trigger the coughing fits. People who are unvaccinated, whose immunity has faded, or who are in close contact with an infected person are at higher risk of catching it.

How is a pertussis diagnosis confirmed?

Doctors confirm a pertussis diagnosis by combining the pattern of symptoms with laboratory tests. The most common test is a PCR test on a swab taken from the back of the nose, which detects the genetic material of the bacteria. A bacterial culture or a blood test for antibodies may also be used, depending on how long the person has been ill. A chest X-ray is only used if complications such as pneumonia are suspected.

What are the pertussis treatment options for adults?

For adults, pertussis treatment options usually include a course of macrolide antibiotics, which help stop the spread of infection and may shorten the illness if started early. Supportive care at home, including rest, fluids, small meals, and avoiding smoke and irritants, helps manage the cough. Cough suppressants are generally not helpful. Most adults recover at home, but hospital care may be needed if breathing difficulty or pneumonia develops.

How long is a person with pertussis contagious?

Without antibiotics, a person with pertussis may spread the infection from the start of cold-like symptoms until about three weeks after the coughing fits begin. With appropriate antibiotics, most people are no longer contagious after about five days of treatment. Doctors and public health authorities usually advise staying away from work, school, or daycare until that period has passed.

Can pertussis be prevented?

Vaccination is the most effective way to reduce the risk of pertussis. Routine childhood vaccines protect infants and young children, while booster doses for adolescents, adults, and pregnant women help maintain immunity and protect newborns. Protection is not lifelong and not absolute, but vaccinated people who do catch pertussis usually have milder illness. Reviewing vaccination status during a routine check-up and preventive medicine visit can help identify whether a booster may be appropriate.

When to see a doctor

You should arrange a medical evaluation if you or your child has a cough that lasts more than two weeks, comes in fits, or is followed by a whooping sound or vomiting, especially if you know of any contact with someone diagnosed with pertussis. Early assessment allows antibiotics to be started when they are most useful and helps protect others around you.

Seek emergency care immediately if any of the following red-flag signs occur:

• Pauses in breathing or breathing that stops for several seconds, particularly in an infant
• Blue, gray, or very pale color of the lips, face, or skin during or after a coughing fit
• Struggling to breathe, rapid breathing, or the chest pulling in with each breath
• Seizures or unusual limpness and unresponsiveness
• Signs of dehydration such as very few wet diapers, no tears when crying, a dry mouth, or extreme drowsiness
• Repeated vomiting that prevents the person from keeping down fluids
• High fever with worsening cough, which may suggest pneumonia
• Coughing so violent that it causes fainting, severe chest pain, or bleeding

Any baby under six months with a suspected pertussis infection should be seen urgently, even if the symptoms seem mild, because infants can deteriorate quickly and may not show the typical cough.