THE swift onset of deadly meningitis in a child is every parent's worst nightmare. New Dutch research indicates that a susceptibility to develop serious infections from the meningococcus bacteria may run in families, putting people at 20 times greater risk and more. Up to 30 per cent of healthy people have meningococcus bacteria living harmlessly in their nose and throat. Rarely does the bacteria invade the bloodstream and cause devastating, often fatal infections.
To find out why, researchers at Leiden University Hospital took blood samples from relatives of meningitis patients and exposed their white blood cells to a bacterial toxin that usually triggers an immune response. They then measured the levels of two proteins, called cytokines, which immune cells release to regulate the immune system's response to an infection. One of the cytokines, tumour necrosis factor (TNF) stimulates the immune system, while the other, interleukin-10 (IL-10) tends to mute the immune response.
Relatives of patients who have died of their meningococcal infection produced only half as much TNF and twice as much IL-10. Writing in the Lancet, the researchers concluded that the risk of death from meningitis in people from families who produced low levels of TNF were 10 times higher and that those who produced high IL-10 were 20 times more likely to die.