Mode Of Infection
Pertussis (Whooping cough) is caused by the bacterium, Bordetella pertussis. It is highly contagious, easily transmitted form person to person by droplets.
It occurs mainly in infants and young children, and is easily transmitted from person to person, mainly through droplets.
Pertussis is a serious disease of infants and toddlers but in recent years we have seen an upsurge in adults who have never been vaccinated or have lost their immunity.
The first symptoms commence 7–10 days after exposure to an infected person. This person may be asymptomatic or have mild, non-specific symptoms that include mild fever, runny nose and cough. In classical cases the cough develops into a paroxysmal cough followed by whooping (hence the common name of whooping cough).
Very young babies my stop breathing after prolonged bouts of coughing. Pneumonia is a common complication and in some instances the patient may lose consciousness, have a fit or even encephalopathy.
Adults seldom develop the typical ‘whoop’ but may continue coughing for weeks – referred to as ”The Hundred Day Cough”
Pertussis occurs all over the world but may be more common in the developing world if vaccine coverage is poor. The developed world is seeing an increasing number of cases due to a number of factors not least of all complacency amongst the general public leading to dropping immunization cover. In South Africa there are always cases in the community most of which go undiagnosed but acts as a source of infection for others.
The bacteria is transmitted from one person to the next by infected droplets. It is most contagious before the typical cough starts. Newborn babies are at high risk of severe disease and may contract the disease from un-immunised adults or adults who had lost their immunity hence the importance of vaccinating teenagers and adults again at 10 year intervals.
Antibiotics may be effective but only in the first week or two when the disease is often not yet recognized for what it is. Antibiotic treatment does not necessarily shorten the period of coughing.
Universal infant vaccine coverage of more than 90% is necessary to effectively stem transmission. The WHO estimates that global cover is little more than 80% and less so in developing countries including South Africa.
The vaccine is included in the Childhood Immunisation Programme in South Africa but infants may be infected by siblings, parents and grand parents who had either not been vaccinated or have lost their immunity. Therefor all persons should receive a booster every ten years. The vaccine is included in a very cost effective vaccine that also provides protection against tetanus and diphtheria for which ten yearly boosters are also needed.
The vaccine is given to babies as a primary series that forms part of the core of the Expanded Programme of Immunisation (EPI) of the WHO. The vaccine is given at 6, 10 and 14 weeks and a final childhood booster at 18 months. Teenagers should receive a booster at 12 years and so should all pregnant women. All adults should receive a single booster once in adulthood.