Whooping Cough, How Is It Transmitted?

Whooping cough, also referred to as pertussis, is a serious infection of the respiratory tract (breathing tubes and lungs) that is caused by pertussis bacteria. Toxins are released by the bacteria that cause swelling of the airways and damage the cilia. Pertussis causes fits of violent coughing. It is especially harmful in young babies, in whom it can even be fatal. Read on to know more about its method of transmission, symptoms, diagnosis and treatment.

How Is Whooping Cough Spread?

The pertussis bacterium is spread from one person to another in droplets that are airborne or by having direct contact with nasal or throat discharges infected with the bacteria. Sneezing and coughing are the common methods of transmission. After getting infected with the pertussis bacteria, a person may develop symptoms between 5-10 days, thoughsymptoms may appear even after 21 days of initial infection.

The person who has the infection remains contagious from 7 days after getting infected from the pertussis bacteria up to 1 month post the appearance of spasms of coughing. However, the most contagious period is the catarrhal stage.

In case an outbreak of pertussis has occurred, it is recommended to keep children who are uninfected (particularly those who have not received the vaccine) away from source of infection till contagious period is over. Similarly, children suffering from whooping cough should not attend daycare or school till the time they are not infectious.

Signs and Diagnosis of Whooping Cough

After discussing "How is whooping cough spread?" let’s discuss signs and diagnosis of whooping cough.

The first stage of pertussis is referred to as catarrhal stage. In this stage, which lasts from 1-2 weeks, the symptoms are similar to infection of upper respiratory tract. These are:

  • Sneezing
  • Runny nose
  • Fever of low-grade
  • Occasional, mild cough that is similar to common cold

During this stage, patients may think their illness to be common cold and are not aware that their symptoms are due to infection with pertussis bacteria.

Gradually, the cough becomes severe and after 1-2 weeks, second stage starts, which is referred to as paroxysmal stage. During this stage the diagnosis of pertussis is usually suspected. Following symptoms are present during the second stage:

  • Paroxysms or bursts of coughing characterized by numerous rapid bouts of cough are present. This occurs as there is difficulty in expulsion of thick mucus from the lungs. Frequency of coughing paroxysms increase during the initial 1-2 weeks; is constant for 2-3 weeks and gradually the frequency start to decrease.
  • At the end of paroxysm of rapid coughs, there is a long breathing in, which is accompanied by a high-pitched sound of whoop.
  • During the attack of coughing, the person’s mucous membranes and skin may become blue due to deficiency of oxygen.
  • Young infants and children appear particularly distressed and ill.
  • Coughing episodes are followed by exhaustion and vomiting.
  • The patient usually looks normal in between episodes.
  • Episodes of cough occur more at night.
  • This stage lasts from 1-6 weeks but may remain for up to 10 weeks.

The third stage of pertussis is referred to as the convalescent or the recovery stage. In this stage there is gradual recovery. The paroxysms of cough become less and it disappears over 2-3 weeks. But, paroxysms of cough may recur due to subsequent infections of the respiratory tract afterwards.


When the usual symptoms of pertussis are present in a patient, the physician can make the diagnosis by taking the clinical history of the patient. However, the symptoms of the disease and its severity may vary in different persons. Lab tests can be done in cases where diagnosis is uncertain or when a physician wants to confirm a diagnosis. Diagnosis can be established by culturing the bacteria Bordetella pertussis from secretions of the nose. Another test to diagnose whooping cough is the PCR (polymerase chain reaction) test in which genetic material of the bacteria is identified in the nasal secretions.

Treatment and Prevention of Whooping Cough

How is whooping cough spread? You already know the answer.But how to treat and prevent it?


Antibiotics are given to treat whooping cough. They most effectively reduce the severity of the disease when they are given during the initial stages. When they are given during the later stages, they may reduce the spread of bacteria but may not decrease the severity of disease symptoms.

Antibiotics are also prescribed for secondary infections if they have occurred. Preventative (prophylactic) antibiotic therapy may be advised for other family members to prevent spread of whooping cough.

Apart from antibiotic therapy, supportive care is provided to the patient, which involves providing a comfortable environment to the child. This includes:

  • Providing bed rest
  • Giving small meals at frequent intervals
  • Maintaining adequate hydration by giving plenty of fluids to drink

A humidifier should be used to moisten and warm the air. It helps in reducing spasms of coughing and soothing airways. Making the child sit in a steam-filled bathroom is also beneficial.

Medicines to suppress cough are not beneficial in treating pertussis.Treatment of severe cases of whooping cough may require hospital stay. This is commonly needed in infants below 6 months.

Treatment given in hospital includes:

  • Oxygen may be administered.
  • Mucous and secretions may be removed by suctioning.
  • Fluids may be administered intravenously through an IV drip in the arm to prevent dehydration.
  • Signs of complications are monitored.
  • The child is isolated from other children so as to prevent spreading the disease.


Young children and infants are commonly affected by pertussis but the disease can be prevented by immunization of the children by pertussis vaccine. This vaccine is commonly given combined with diphtheria and tetanus vaccines. (The P in the DTaP vaccine that is routinely administered to children and “p” in the Tdap vaccine which is given to adults and adolescents is pertussis).

For maximum protection from whooping cough, children should get 5 DTaP shots. The initial 3 shots are given at two, four and six months of age. The 4th shot is given between 15-18 months of age. The 5th shot is given at 4-6 years of age. A Tdap booster should be given to preteens at 11 or 12 years and adults who have not received Tdap as a teen or preteen should receive one dose of Tdap.

Vaccines in adults are given to prevent the transmission of bacteria to infants who have the greatest risk. Adults should get a booster dose if:

  • They work in such profession that it requires regular contact with newborn infants.
  • They get pregnant (usually between 28 and 39 weeks during pregnancy).
  • They care for or live with infants less than 1 year of age, even if all the vaccines has been given to the baby.

Boosters must also be given to other individuals who are prone to develop pertussis and are at high risk of developing severe disease or complications, for instance, those who have immunodeficiency, congenital heart disease or chronic conditions of the respiratory tract.