A 21-study meta-analysis finds that the median incubation period for the global mpox outbreak that began last year is 7 days, symptoms vary widely, and immunocompromised people with HIV make up 36.1% of documented cases. The study is published in Archives of Virology.
This clinical review comes more than 1 year after countries around the world began seeing mpox as a sexually transmitted infection in communities that had never before seen the virus.
The studies included in the review described clinical presentation in 18,275 mpox cases. Most cases were caused by person-to-person transmission, and most infected men who have sex with men—the vast majority of patients—were young (30 to 40 years). Though the median incubation period—the time from exposure to symptom onset—was 7 days, the interquartile range was 3 to 21 days.
The clinical manifestations of mpox infection were severe skin lesions on the palms, oral, and anogenital regions, as well as proctitis, penile edema, tonsillitis, ocular disease, myalgia, lethargy, and sore throat. Unlike previous outbreaks of mpox, most patients do not experience a preceding fever before developing blisters.
Rash often first clue
"Instead, the illness often starts with a rash that appears as papules or blisters, which can be painful or itchy and progresses through several stages, forming crusts before healing," the authors wrote. Asymptomatic cases were also documented, but the study authors didn't specify how common they were.
Notably, the authors of the study said, hospitalizations, including admissions to intensive care units, have increased during the global outbreak. Among 84,470 cases reported since May of 2022, 80 deaths have been reported in 103 non-endemic countries.