The first study of 54 monkeypox patients in the UK found their symptoms differed from those seen in previous outbreaks and could potentially be compared to other infections such as herpes and syphilis, increasing the risk of misdiagnosis. “Misdiagnosis of infection can prevent the opportunity for appropriate intervention and prevention of further transmission,” said Ruth Byrne of Chelsea and Westminster Hospital NHS Foundation Trust and one of the authors of the study published in The Lancet Infectious Diseases journal. “Additional resources are urgently needed to support services in managing this situation.” Britain and other countries are seeing a rapid increase in cases of monkeypox among people in sexual health clinics, with no apparent links to countries where the disease is endemic, the authors said. In the past two weeks, cases have tripled in the European region, the World Health Organization said on Friday. The agency said most infections are in men who have sex with men, but small numbers are now being reported among household members, heterosexual and non-sexual contacts, and children. More than nine out of 10 patients in the UK study had monkeypox lesions in the genital area – a distinct feature of the current outbreak and a driver of the virus’s explosive spread through sexual networks. The research also found a lower prevalence of fatigue and fever than in previous outbreaks. The patients account for 60% of cases reported in the UK during a period in May, and all identified as men who have sex with men. At least one in six of the patients in the study would not meet the current definition of possible monkeypox, according to Nicolo Girometti, who is also at Chelsea and Westminster Hospital. “We suggest that case definitions detailing symptoms such as acute febrile illness be revised to better accommodate the current findings,” he said. The authors acknowledged some limitations with their study, notably that it was observational and retrospective and may not be representative of the overall outbreak. The findings confirm smaller studies from other countries that the initial onset of monkeypox can be “subtle and mimic many sexually transmitted infections,” said Hugh Adler of the Liverpool School of Tropical Medicine, who was not involved in the study. He added that current case definitions in the UK are broader now than when the data for this paper was collected. ©2022 Bloomberg LP