Before routine vaccination was introduced, thousands of children in Europe and around the world died of diphtheria - a very contagious disease that significantly affects breathing and often results in the death of the person catching it.

Diphtheria is caused by the diphtheria bacterium that multiplies on the lining (or mucous membrane) of the throat and excretes a poisonous substance (or toxin).

The action of the bacterium and toxin destroys the mucous membrane. Then a thick coating is formed over the membrane causing a serious inflammation of the throat which leads to breathing problems.

Swollen glands under the throat worsen the condition. Sometimes the thick coating can become detached and block the airway completely causing death by suffocation. Most who die from diphtheria die in this way.

Diphtheria symptoms present about three to five days after exposure to someone else with the germ. Those with diphtheria get a fever and sore throat and often a croup-like cough.

In other cases the Diphtheria toxin invades the body where it can cause heart problems and even cardiac arrest.

In addition, Diphtheria is very contagious. Transmission generally occurs by inhaling the droplets of an infected person's breath. Anyone unlucky enough to be near a person with diphtheria who is sneezing or coughing usually contracts the disease as well.

For all these reasons, Diphtheria is a very serious condition but is now completely preventable by vaccination.

Though vaccinations against the disease were only started in the 1950s, it has now been virtually eradicated in Europe and North America.

However, it is still a huge threat in countries where vaccination is unaffordable.