Pertussis (Whooping Cough)

Dr. Parang Mehta, MD.

Whooping cough is a highly infectious disease, and was very common in children before the vaccine came into use.  It is caused by a bacterium, Bordetella pertussis.  The distictive feature of this illness is a severe cough.  The cough occurs in bouts, and after a prolonged bout, the child draws in a long breath with a distinctive whoop.  However, not all children with this illness have the whoop, and the scientific name is therefore pertussis -- intense cough.

Whooping cough is very infectious, and difficult to treat. Vaccination had controlled it, but outbreaks are occurring now

Unlike many diseases such as measles and mumps, babies get no antibodies or other protective factors against whooping cough from their mothers.  Therefore, even newborn babies can get whooping cough.  

The universal use of the pertussis vaccine (as a part of the DTP vaccine) has made whooping cough an uncommon disease.  Before the vaccine was in use, whooping cough was the most common cause of death of children, among infectious diseases.

The Disease

Whooping cough is described as a six week disease, divided into three stages.  The first, or Catarrhal stage consists of cold, cough, red eyes, and fever.  In the second, or Paroxysmal stage, the cough gets worse and worse.  It is initially dry and irritative, but evolves into the typical paroxyms of cough with whoop after a few days.  The coughing is very severe, and makes breathing and feeding difficult, especially in young children.  Many children vomit after the paroxysm of cough.

The cough bouts are provoked by eating, drinking, laughing, crying, cold air draughts, and even light and sounds.  These paroxysms increase in frequency and severity for a week, and remain at that severity for several weeks.  During the third, Convalescent stage, the bouts of cough become less severe and frequent.  The disease is very severe and even life threatening in babies less than 3 months old.

Whooping cough has become rare in countries where most children are vaccinated.  For this reason, it may not be suspected and diagnosed in the first few days.

Spread of Whooping Cough

Whooping cough is a highly infectious.  It is spread by infective droplets coughed up by a child with the disease.  Among children who are not immune, the infection rate is 97%.  Only measles, and chicken pox in the home setting, are more infectious than whooping cough.

Immunity to whooping cough is achieved by either getting the disease, or the vaccine.  Neither of these gives life long immunity, though.  The immunity after getting the disease starts declining after 5 years, and is gone by 12 years.  However, immunity can be maintained by the effect of frequent infections with the whooping cough bacterium, even if this does not cause the disease.  Where whooping cough is rare, this frequent infection does not occur, and adolescents often get whooping cough.

Treatment of Whooping Cough

Whooping cough is a bacterial disease, but antibiotics play only a small role in treatment.  This is because killing the bacteria does not stop the paroxysms of cough.  Antibiotics should be given though -- they eradicate the infection and reduce spread of the disease.

The main aim of treatment is to reduce the cough paroxysms.  This is very difficult, as most cough medication is not effective in this severe cough.  Young babies (less than three months) should be hospitalised, bacause the disease can be serious.  Cough should be reduced by reducing the stimuli that provoke it.

The disease goes on for weeks.  Children need reassurance and support during this difficult period.  They also need attention to nutrition.  Many children lose weight and become malnourished during an episode of whooping cough.

Complications of Whooping Cough

Whooping cough itself is more troublesome than dangerous.  However, the severe prolonged cough can cause several types of complications, some of which are dangerous.  Whooping cough is more severe at younger ages, and children less than six months of age have a higher rate of complications.

Whooping cough causes death in less than one percent of cases, and most of these are children less than a year old.  Most deaths are caused by pneumonia.

Outbreaks of Whooping Cough

Pertussis had been under control in many countries for decades, because of high vaccine coverage.  However, the vaccine itself caused significant local pain, fever, and other effects.  A new vaccine, called the acellular pertussis vaccine came into use in the 1990s.  It has significantly fewer side effects, and has replaced the older whole cell vaccine in many countries.

Unfortunately, we now know that the immunity induced by this vaccine does not last very long, and there have been outbreaks of whooping cough in USA, Australia, and Europe in recent years.  Various strategies are being tried to deal with this issue.

Prevention of Whooping Cough

 

Last Revision: May 22, 2020