Why is this meningitis outbreak so explosive?

"This meningitis outbreak is deeply unusual and defies easy explanation. It has been described as unprecedented and explosive because there have been 20 cases since the weekend in one small area of Kent. This is not the normal pattern. Meningitis typically occurs as isolated one-off cases."

"We know people regularly catch meningitis B bacteria and they usually live harmlessly in the nose. Across the UK about 10% of us have these bugs, but in teenagers and young adults it's as high as 25%. It's only in a tiny number of cases that the bacteria cross the barriers inside our nose to invade the body and cause meningitis and sepsis."

"For Prof Andrew Preston, from the University of Bath, there are two broad explanations for the numbers getting severely ill and dying in Kent. He told me there has either been an 'astonishing rate of transmission' meaning so many more people are catching the bacteria, or the infection is proving to be 'more invasive' this time."

Kent is experiencing an exceptional meningitis outbreak with 20 cases reported in a single week, an unprecedented rate compared to historical patterns where meningitis typically occurs as isolated cases or small clusters. The 1980s Gloucestershire outbreak of 65 MenB cases unfolded over four-and-a-half years, not days. Meningitis B bacteria normally reside harmlessly in nasal passages, affecting approximately 10% of the UK population and 25% of teenagers and young adults. The infection rarely crosses barriers to invade the body and cause severe disease. Eleven of the first fifteen affected cases had attended Club Chemistry nightclub, though this connection alone doesn't explain the outbreak's severity. Experts propose two explanations: either an exceptional transmission rate or increased bacterial invasiveness in this outbreak.

Read at www.bbc.com