Background: In 2022, there were outbreaks of Mpox where the disease is not endemic. We summarised and compared the findings from published observational studies on the clinical presentation and epidemiology of the 2022 and previous outbreaks of Mpox.
Methods: We registered a review protocol with the Open Science Framework (osf.io/j3kb7). We searched MEDLINE, Embase, CENTRAL, CINAHL and Scopus databases, and relevant websites up to August 30, 2022. Retrieved literature citations were screened for eligibility, and summary clinical presentation and epidemiological data from the included studies were pooled, when possible, using an inverse variance, random-effects model.
Results: Seventy-nine studies met the eligibility. Irrespective of outbreak, fever, headache, myalgia, lymphadenopathy, pleomorphic skin lesions, oral lesions, and sore throat were potentially highly relevant Mpox manifestations, while conjunctivitis, cough, and possibly reactivation of varicella zoster virus may be part of the clinical presentation. The mean incubation period for the 2022 outbreaks was 7.4 d (6.4-8.4 d, I2 64.2%; 4 studies: 270 cases) and for previous outbreaks, 12.9 d (10.4-15.5 d; one study: 31 cases), p < .001. None of the male cases from previous outbreaks was reported to have sex with men (MSM) whereas almost all reported male cases from the 2022 outbreak were MSM. Concomitant sexually transmitted infections and perianal lesions were reported only among male cases from the 2022 outbreak, with the cases mostly presenting with genital lesions.
Conclusions: The 2022 Mpox outbreaks appear to be mostly among MSM and have a lower incubation period compared with previous outbreaks.Key messages79 studies met the review's inclusion criteria.The 2022 Mpox outbreaks appear to have shorter incubation period compared with previous outbreaks.Established clinical presentation of Mpox includes fever, headache, myalgia, lymphadenopathy, pleomorphic skin lesions, oral lesions, and sore throat.Almost all reported cases from the 2022 Mpox outbreaks were men who had sex with men (MSM).Concomitant sexually transmitted infections and perianal lesions were only reported among cases from the 2022 Mpox outbreaks.A significantly higher proportion of Mpox cases from the 2022 outbreaks had genital lesions compared with cases from previous outbreaks.The 2022 Mpox outbreaks appear to be mostly among MSM.
Keywords: Mpox; clinical presentation; epidemiology; meta-analysis; systematic review.