Although several different bacteria and viruses cause meningitis, meningococcal bacteria cause one of the most devastating forms of the disease - meningococcal meningitis, which is fatal in approximately one in ten cases. Meningococcal septicaemia is a type of blood poisoning that often accompanies this form of meningitis.
Meningococcal meningitis and septicaemia most commonly affect children and young adults. There are vaccines available against some strains of meningococcal bacteria but not others. The researchers hope that their new findings will boost the development of effective vaccines to combat the group B strain of the bacteria, for which there is currently no vaccine.
The study compared the genetic makeup of 1,500 people who developed meningococcal meningitis with over 5,000 healthy controls. Researchers looked at genetic variants scattered across each person's genome, and searched for differences between the patients with meningococcal disease and healthy controls. The results revealed that those who had developed meningococcal meningitis had genetic markers in a number of genes involved in attacking and killing invading bacteria.
Professor Michael Levin, from Imperial College London, who led the research effort, said: "Although most of us have carried the meningitis bacteria at some point, only around one in 40,000 people develop meningococcal meningitis. Our study set out to understand what causes this small group of people to become very ill whilst others remain immune. Our findings provide the strongest evidence so far that there are genetic factors that lead to people developing meningitis."
The variations uncovered in the study were around the genes for Factor H and Factor H-related proteins. These proteins regulate a part of the body's immune system called the complement system, which recognises and kills invading bacteria. Normally, Factor H and Factor H-related proteins ensure that the complement system does not cause excessive damage to the body's own cells. However, meningococcal bacteria can hijack the body's Factor H and use it to ensure that the body does not recognise the bacteria as foreign.
MEDICA.de; Source: Imperial College London