LONDON, Sept. 22 (Xinhua) -- British scientists have identified genetic changes that may explain the severity of a deadly meningococcal disease outbreak in southern England earlier this year, warning that similar outbreaks could emerge suddenly and unpredictably.
The outbreak, linked to a nightclub in Canterbury in March, saw 21 people diagnosed with invasive meningococcal disease within a week. All required hospital treatment, including nine who needed intensive care, while two died.
According to findings released Tuesday by the UK Health Security Agency (UKHSA), researchers from the agency, the University of Oxford and other academic institutions compared the outbreak strains with tens of thousands of meningococcal genomes held in international databases.
They found that the bacteria had acquired genetic material from less harmful bacteria naturally present in healthy people's throats. These changes appeared to have made the strain more effective at causing severe disease and potentially less easily recognised by the human immune system.
Comparisons with historical outbreaks, including one at the University of Southampton in 1997, revealed similar patterns of bacterial evolution, suggesting that such changes might contribute to rare but severe outbreaks associated with close social mixing.
Charlene Rodrigues, consultant in pathogen genomics at UKHSA, said the nightclub environment had contributed to the strain spreading among so many young people.
The same genetic changes that made the strain dangerous may also explain why it has not spread widely since the outbreak was brought under control, she said.
"But that is not something we could have predicted and these genetic events can happen again," Rodrigues warned.
England's national surveillance programme has routinely sequenced bacteria from every culture-confirmed case of invasive meningococcal disease since 2010, enabling scientists to detect unusual strains and track their genetic evolution, UKHSA said.
During the Canterbury outbreak, scientists identified the strain within days of the first reported case, helping guide contact tracing, preventive antibiotics and targeted vaccination that brought the outbreak under control.
Rodrigues stressed that the unpredictable emergence of dangerous strains underscored the importance of continued genomic surveillance, rapid public health responses, vaccination and public awareness of meningococcal disease.
