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What is meningococcal disease?
Meningococcal disease is illness – specifically, meningitis and/or septicaemia – caused by the Neisseria meningitidis, or meningococcus, bacteria. Meningitis and septicaemia can occur on their own, but often occur together.
There are 12 identified groups of meningococcal bacteria (meningococci) and, of these, five commonly cause disease — they are groups A, B, C, W and Y.
Meningitis is the inflammation of the meninges. These are membranes that surround the brain and the spinal cord, and help protect the brain from injury and infection.
Meningitis occurs when bacteria or viruses invade the bloodstream and infect the meninges. The bacteria or viruses multiply rapidly and cause the meninges to inflame and swell. The brain is subjected to an increase in pressure that can cause symptoms such as a headache and a stiff neck.
Septicaemia is caused by bacteria multiplying in the bloodstream. The bacteria release toxins that damage the walls of the blood vessels, causing them to leak. The immune system is unable to counteract these toxins.
As the vessels leak, the body reacts by reducing blood supply to the hands, the feet and the surface of the skin. The heart and lungs have to work harder to supply oxygen and nutrients to the vital organs.
The toxins released by the bacteria also affect the clotting mechanism, which in turn affects the blood supply to the vital organs, causing tissue damage. The rash associated with septicaemia is caused by blood leaking into tissues under the skin.
How is meningococcal disease contracted and spread?
Meningococci are spread through coughing, sneezing and intimate kissing — approximately 10% of the general population carry meningococcal bacteria harmlessly in the back of their throats at any one time. This natural carriage is, therefore, relatively common and helps develop immunity.
Only a minority of carried meningococci are harmful. Infection is caused when the bacteria, for reasons that are not currently understood, move from the back of the throat into the bloodstream and multiply rapidly. Once in the bloodstream, these bacteria can cause septicaemia and, in many cases, infect the meninges and cause meningitis.
There are between 750 and 2,800 cases of meningococcal disease in the UK each year. When a case occurs, public health action will identify close contacts and offer them antibiotics. This reduces the risk of further cases occurring. It is still vital for these contacts to be aware of the signs and symptoms of meningitis and the action to take if symptoms appear.
What are the consequences?
Author: Meningitis Now