Retrospective testing for mpox virus in routine STI screens from men who have sex with men in England, August-October 2022.

OBJECTIVES: A global outbreak of mpox (monkeypox) has been ongoing since 2022, with most cases in the UK detected in gay, bisexual and other men who have sex with men (GBMSM). Asymptomatic and pauci-symptomatic mpox infection has been reported outside of the UK. We aimed to investigate whether mpox could be detected in specimens from GBMSM in England who were attending sexual health services (SHSs) for asymptomatic sexually transmitted infection screening. METHODS: Anonymised, residual clinical specimens from GBMSM undertaking routine asymptomatic screening for gonorrhoea (Neisseria gonorrhoeae (NG)) and chlamydia (Chlamydia trachomatis (CT)) infection were tested for the presence of mpox virus. Specimens were collected between 1 August and 7 October 2022 from three SHSs in high-mpox incidence areas in England. Testing was performed using a dual-clade, mpox virus-specific real-time PCR. RESULTS: During the collection period, 2927 clinical specimens (951 pharyngeal swabs, 1022 urine specimens and 954 rectal swabs) were obtained from 1159 GBMSM. Mpox virus was detected in four specimens from two participants who attended the same SHS at different times (the first during the week 8-12 of August, the second during the week 19-23 of September). One participant was positive in the urine specimen only, while the other tested positive at all three sites. CONCLUSIONS: A very low prevalence (2 of 1159, 0.17%) of mpox infection was detected in GBMSM attending SHS in England for asymptomatic NG/CT screening, suggesting that undetected infection in this population was unlikely to be a main driver of transmission. Confirmed mpox cases in the UK declined from over 1100 per month in June and July to 764 cumulatively during the collection period. These data give reassurance that the observed reduction in cases during the collection period was not due to undetected infection or changes in presentation among SHS attendees. Currently, there is insufficient evidence to support routine testing of asymptomatic GBMSM for mpox infection in England.

Rapid expansion and international spread of M1UK in the post-pandemic UK upsurge of Streptococcus pyogenes.

The UK observed a marked increase in scarlet fever and invasive group A streptococcal infection in 2022 with severe outcomes in children and similar trends worldwide. Here we report lineage M1UK to be the dominant source of invasive infections in this upsurge. Compared with ancestral M1global strains, invasive M1UK strains exhibit reduced genomic diversity and fewer mutations in two-component regulator genes covRS. The emergence of M1UK is dated to 2008. Following a bottleneck coinciding with the COVID-19 pandemic, three emergent M1UK clades underwent rapid nationwide expansion, despite lack of detection in previous years. All M1UK isolates thus-far sequenced globally have a phylogenetic origin in the UK, with dispersal of the new clades in Europe. While waning immunity may promote streptococcal epidemics, the genetic features of M1UK point to a fitness advantage in pathogenicity, and a striking ability to persist through population bottlenecks.