The cause of the severity of Kent’s meningitis B (MenB) outbreak earlier this year has been revealed by scientists at the UK Health Security Agency (UKHSA) and the University of Oxford.
UKHSA said scientists used genome sequencing to identify genetic changes in the bacteria responsible and compared all the outbreak strains “against tens of thousands of meningococcal genomes held on international databases”.
Their findings, published on September 22, concluded that the outbreak bacteria “had picked up genetic material from other, less harmful bacteria found naturally in the throats of many healthy people”.
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The process, known as “horizontal gene transfer”, appears to have altered how the bacteria interact with human cells, making the strain involved in the outbreak “unusually effective at causing severe disease and potentially less well recognised by human immune responses”.
UKHSA added that “the same changes that made it so dangerous may also explain why it has not continued to spread widely since the outbreak was brought under control”.
“Likely to occur again”
The body said the research team also compared the Kent outbreak with historical outbreaks and found “striking similarities” in how the bacteria evolved in an outbreak at the University of Southampton in 1997.
This suggests this “is a recurring pattern behind rare, intense clusters of meningococcal disease often associated with events with intense social mixing”, it noted.
UKHSA added that “because these highly invasive strains can emerge suddenly and unpredictably, similar outbreaks are likely to occur again” - but that exactly when and where is “impossible to predict”.
The MenB outbreak in March was linked to a single Canterbury nightclub over one weekend, seeing 21 people diagnosed with invasive meningococcal disease (IMD). All those affected required hospital treatment, nine needed intensive care and two died.
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UKHSA consultant in pathogen genomics Dr Charlene Rodrigues said the investigation “shows just how quickly and dramatically these bacteria can change, sometimes acquiring new traits from harmless bacteria circulating nearby, that make them more likely to cause disease”.
UKHSA said it continues to monitor IMD across England through its national genomic surveillance programme.
“This capability, combined with the UK’s established vaccination programme, remains central to efforts to protect the public from this rare but life-threating disease,” it added.
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It comes after pharmacies faced an “unprecedented” demand in March for meninigitis vaccines amid the outbreak in Kent.
And it follows NHS England figures from earlier this month revealing that 246,089 MenB vaccines were adminstered between July 20, when the one-off pharmacy MenB vaccination was launched, and August 31.
