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A recent study led by researchers at Imperial College London and the UK Health Security Agency has shed light on a concerning surge in severe invasive Strep A infections that swept across the globe following the relaxation of pandemic restrictions. Identified as a key player in this increase is a variant known as M1UK, which belongs to the Group A Streptococcus bacteria family.
Group A Streptococcus, commonly referred to as Strep A, is notorious for causing throat infections and scarlet fever. While most infections are mild, there exists a rare but grave possibility of invasive infections that can prove fatal.
The period of 2022–2023 witnessed a notable uptick in severe invasive Strep A infections worldwide, prompting health agencies to delve deeper into the underlying factors. The research, detailed in a study published in Nature Communications, uncovered that the emergence of the M1UK variant significantly contributed to this surge.
M1UK, a subtype within the M1 strains of Strep A, has garnered attention for its propensity to cause more invasive infections compared to other variants. Initially identified and sequenced in the UK, M1UK has since been implicated in the rise of severe infections not only in Europe but also in regions as distant as Australia, North America, and Japan. Its presence has also been detected in South America, New Zealand, and Taiwan, underlining its global reach.
The study delved into the genetic makeup of M1UK, offering insights into its origins and characteristics compared to other strains. Through genetic sequencing and computer modeling, researchers determined that M1UK likely emerged around 2008, with its prevalence steadily increasing from 2010 onwards.
One notable feature of M1UK is its heightened production of toxins associated with scarlet fever, distinguishing it from earlier M1 strains that remained relatively unchanged over several decades.
Professor Shiranee Sriskandan, leading the research at Imperial College London, emphasized the evolutionary nature of bacteria and the necessity to monitor their genetic changes closely. She remarked, “Bacteria evolve over time, and as Strep A is an exclusively human pathogen, it will acquire genetic changes as it spreads in the population.”
The study also highlighted the rapid spread of M1UK beyond the UK, with the variant now identified in over 10 countries worldwide. This expansion coincided with a decline in Strep A infections during the COVID-19 pandemic, followed by a resurgence post-pandemic, particularly in the UK, where M1UK became a dominant strain.
While reduced transmission during the pandemic may have contributed to waning immunity against Strep A in the population, the study suggests that genetic advantages of M1UK may have facilitated its spread and increased severity of associated diseases.
Professor Sriskandan emphasized the importance of vaccination in combating Strep A infections, calling for the development of a Strep A vaccine. She underscored the significance of collaboration between infectious disease researchers and molecular surveillance agencies in addressing emerging health threats.
As the world grapples with the aftermath of the COVID-19 pandemic, understanding and mitigating the spread of bacterial pathogens like Strep A remain crucial for safeguarding public health on a global scale.
