Diphtheria

Health and Nutrition > Diseases > D Written by Dr Charlie Easmon, specialist adviser in travel medicine

What is diphtheria?

Diphtheria is an acute respiratory infection caused by the diphtheria bacterium, Corynebacterium diphtheriae and its toxin. This is a serious infection with a high mortality rate, even in Western Europe.

The bacteria multiply on the lining (mucous membrane) of the throat, nose or larynx, where they divide and excrete a poisonous substance or toxin.

The bacteria and the toxin destroy the mucous membrane, so that a thick coating is formed and the patient develops a serious inflammation of the throat.

The membranous coating in the throat can become detached and obstruct the airways, making breathing difficult and sometimes causing asphyxiation. The bacterial toxin penetrates the body and can lead to damage of the cardiac muscle and the nervous system.

Why do you get diphtheria?

The disease is mainly transmitted by droplets from the nose or throat being passed from person to person, eg by coughing or sneezing.

Protection from the disease comes from having antibodies in the blood - which is the purpose of vaccination. The bacteria can easily be passed on by a person who shows no sign of illness, a so-called 'healthy disease carrier'.

Diphtheria can also be transmitted by skin-to-skin contact.

Where does diphtheria occur?

The bacteria may be found anywhere, but especially in poor or densely populated areas, where some people have not been vaccinated against diphtheria, encouraging the disease to spread. In the early and mid 1990s more than 50,000 people in Russia and the Baltic countries fell ill with diphtheria. More recently there have also been minor epidemics in South East Asia.

In Western countries the disease is rare and there have been no epidemics since the 1940s, when the diphtheria vaccine was introduced. However, individual cases will still be seen, because a minority of the population is not totally protected by vaccination, and diphtheria can be imported from abroad.

What are the symptoms of the disease?

The incubation period, which is the time that elapses between a person being infected and the disease developing, is usually two to five days.

Local symptoms consist of a sore throat, coughing and breathing difficulties. When the disease infects the skin it causes crusty scabs, similar to impetigo.

General symptoms manifest themselves as a slight rise in temperature, limpness and fatigue. In weeks two to six of the illness, damage to the heart and nervous system may be observed in the form of irregularities of the heart beat and paralysis.

In the worst cases, this may cause serious disturbances in cardiac rhythm, and possibly cardiac arrest.

Mortality in poorer countries is high, up to 30 to 40 per cent, while in Western countries it is between 5 and 10 per cent, partly because the disease may be confused in the early stages with other infections, which results in treatment being started too late.

What measures can you take to avoid the disease?

. The most important method of avoiding the disease is vaccination. All children in the UK are routinely offered five vaccinations against diphtheria in the child vaccination programme.

Children are given the diphtheria vaccine together with vaccines against tetanus, whooping cough, polio and Hib as one combination vaccine (Pediacel), at the ages of two, three and four months. A child is given a diphtheria, tetanus, whooping cough and polio booster vaccine (Repevax) when he or she is five years old.

The child is given a further booster vaccine before leaving school (Revaxis) and is then considered to be protected for a further 10 years.

If you plan to travel abroad, many places recommend reinforcing protection with a new diphtheria vaccination every 10 years.

How is the diagnosis made?

To make a diagnosis a swab is taken from the throat and the bacteria are cultured in a laboratory.

Future prospects

Provided that treatment is introduced early enough, the danger of asphyxiation can be avoided and there is every possibility that the bacteria can be eliminated and the toxin prevented from affecting the heart and nervous system.

Long-term effects may be observed in the form of paralysis, especially in the face, as well as disturbed cardiac rhythm, which may require ongoing medication.

The disease itself will probably be difficult to eradicate from the planet partly because, like whooping cough, the bacteria can be dispersed among vaccinated and healthy people without anyone realising that they have the bacteria in their throats.

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