A study, published in the Journal of Infectious Diseases, by researchers from Leicester, the University of Nottingham and Public Health England collaborate to explore the reasons behind 2013’s rapid expansion in MenW ST11, a specific strain of Neisseria Meningitidis.

“Since 2009 there has been a significant increase in the number of young adults carrying MenW ST11, and in the number of cases of disease caused by it. In 2013, a new version of this strain emerged and spread rapidly across the UK.

Simple repeating regions of DNA allow bacteria to vary how their surface appears to the human immune system. In their work, the researchers found evidence that the rapid expansion of the 2013-strains was linked to increases in the length of these repeating regions. These changes resulted in making some important surface structures more variable. This process, known as phase variation, allows bacteria to reversibly adapt to different environments.

This implies that this particular N. meningitidis sub-lineage is better able to avoid the human immune system during carriage in the upper respiratory tract and as the bacteria transmit from person-to-person. This immune avoidance attribute may have allowed these hyper-virulent meningococcal strains to spread rapidly throughout the UK population.”

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