Pertussis (whooping cough)

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at February 3, 2016
StartDiseasesPertussis (whooping cough)

Pertussis is an extremely contagious respiratory tract infection that is spread through the air. It is also called whooping cough or 100-day cough because it causes fits of severe coughing. Whooping cough can easily be prevented with the pertussis vaccine at an early age.


Definition & Facts

Pertussis is caused by the Bordetella pertussis bacterium, which is transmitted through sneezing and coughing. It is a very contagious bacterial infection, and people of all ages can be infected with whooping cough. Adults are less likely to be severely affected by whooping cough, but it can be very problematic for young children. Babies who are less than a year old can die if they get whooping cough.

Roughly 48.5 million people worldwide are affected worldwide, primarily in developing countries, including India and several African nations. In the past few years, about 61,000 people, mostly infants, died from whooping cough each year. Incidences of whooping cough is starting to rise again in the United States.

Symptoms & Complaints

After first being exposed to the whooping cough bacterium, symptoms will normally not appear for about seven to ten days. At first, the symptoms of whooping cough mimic those of the common cold, and people have a runny nose, congestion, a slight cough, and a fever.

However, after one or two weeks of these symptoms, mucous congestion in the throat increases, and the coughing turns into fits of uncontrollable coughing. This is called the catarrhal phase. During these fits, it is difficult to inhale, and a patient may make a high-pitched sound, similar to “whoop,” which is where the disease gets its name from.

The coughing attacks are extremely exhausting, and vomiting or difficulty breathing can occur from the extreme coughing. Coughing fits from pertussis can be so strong that they can cause cracked ribs or bruised ribs, break blood vessels along the skin, or cause abdominal hernias to develop.

After two to eight weeks of extreme coughing attacks, the coughing decreases and the disease gradually goes away. Complications from whooping cough can include seizures, pneumonia, and earaches, and it has a fatality rate of about 1.6% for hospitalized infants under the age of one.


The Bordetella pertussis bacterium causes pertussis by infecting the cells of the host’s lungs. The bacterium makes a toxin that paralyzes the cilia in the lungs, which are typically responsible for clearing out debris which is breathed in during the average day. Without the ability to clear up debris, the lingering debris in the lungs triggers coughing fits.

When a person has a coughing fit from all of the Bordetella pertussis in their lungs, small amounts of the bacteria are expelled, traveling through the air. The bacteria can be inhaled by healthy people who are not immune to the whooping cough bacteria, causing them to develop pertussis. If the Bordetella pertussis bacteria lands on a surface, it can live for up to five days outside of a host, infecting anyone who touches the surface.

People are most likely to spread the bacteria during the first five weeks after they start coughing. Pertussis is typically spread from human to human, but it can be spread through animals. Certain strains of the bacteria can affect primate species, including gorillas and monkeys, and then the animals can spread it back to humans. Most zoos vaccinate their primates in order to prevent them from spreading whooping cough to guests.

Diagnosis & Tests

In early stages, whooping cough mimics many other milder respiratory infections, making it difficult to determine whether a patient has pertussis or just a cold. Therefore, many doctors run diagnostic tests to discover whether or not a patient has whooping cough. A blood count is also a useful diagnostic tool. If a person has whooping cough, the lymphocytes and white blood cells in the blood will be elevated because the body is attempting to fight off an infection. This general test merely tells the doctor if you have an infection, and it does not necessarily indicate whooping cough.

A swab from the nose or throat can be checked to see if Bordetella pertussis bacteria is present. However, the bacteria only show up during the first three weeks of pertussis, and after that, a nasopharyngeal swab is not that helpful during a diagnosis. In later stages, a serological diagnosis test can be used to determine if antibodies that fight off pertussis are present in blood samples. Chest X-rays are sometimes used for a diagnosis, because a doctor may want to check if pneumonia is further complicating the pertussis.

Treatment & Therapy

The treatment methods for whooping cough will depend on the severity of the illness. If an infant has whooping cough, they are typically hospitalized immediately because it is so dangerous to young children. Older children and adults can typically remain at home, but they will still need medical care.

The typically prescribed antibiotics are erythromycin, azithromycin, or clarithromycin, which all kill the Bordetella pertussis bacteria. Azithromycin is a short-term antibiotic that has few side effects when compared to erythromycin, which must be taken for a longer period of time. However, these antibiotics are only effective during the earlier stages of whooping cough.

Infants can receive the antibiotics up to six weeks after they first start coughing while adults need to start an antibiotic course within three weeks of their first coughing fit. The antibiotics decrease the infectious stage, so that there is less risk of the pertussis spreading. Over the counter cough medications typically do not help with the cough, and doctors recommend that people do not use them.

Prevention & Prophylaxis

The best way to prevent whooping cough is to get the pertussis vaccine. Taken at a young age, the vaccine prevents infants from developing pertussis, and the only potential side effect is a mild fever or soreness.

Infants are also protected against whooping cough for a few months if their mother was vaccinated around 30 weeks of gestation. Immunity against whooping cough gradually fades, so doctors recommend that a person get a booster shot around the age of 11 or later in adulthood.