Prospective cohort of 70 consecutive cases of human monkeypox: Clinical description with focus on dermatological presentation

A global systematic evidence review with meta-analysis of the epidemiological characteristics of the 2022 Mpox outbreaks

BACKGROUND

In 2022, there were outbreaks of Mpox where the disease is not endemic. We summarized published full-text epidemiological data from the outbreaks.

METHODS

A global evidence review (protocol: osf.io/j3kb7) with systematic literature search up to February 09, 2023. We focused on experimental/observational studies of laboratory confirmed Mpox, excluding case reports and case series of < 5 cases. Epidemiological data were pooled using an inverse variance, random-effects model, and pooled estimates presented with associated 95% confidence intervals.

RESULTS

We included 66 studies. Mean incubation period was 7.8 days (6.6-9.0 days, 8 studies: 560 cases), reproductive number 1.8 (1.7-1.9, 6 studies), mean duration from symptom onset to diagnosis 5.8 days (4.8-6.8 days, 4 studies: 982 cases), mean symptom duration 17.5 days (14.7-20.2 days, 3 studies: 292 cases), mean serial interval 8.5 days (7.3-9.9 days, 1 study), hospitalisation 6% (4-9%, 26 studies: 5339 cases), and vaccine effectiveness 78% (65-91%, 3 studies: 953 cases). Highly relevant clinical manifestations were pleomorphic skin lesions 82% (68-94%, 26 studies: 4093 cases), anogenital lesions 64% (51-77%, 9 studies: 10,398 cases), fever 54% (50-57%, 52 studies: 25,992 cases), and lymphadenopathy 51% (46-57%, 42 studies: 17,803 cases), with cases mostly men who have sex with men (MSM). Possibly relevant manifestations were perianal lesions, fatigue, asthenia, myalgia, and headache.

CONCLUSIONS

The 2022 Mpox outbreaks presented with sex-related clinical manifestations and were mostly reported among MSM.

Mpox: an updated review of dermatological manifestations in the current outbreak

Mpox is a disease caused by a double-stranded DNA orthopoxvirus discovered in 1958. In 2022, an outbreak on an unprecedented scale marked its transition from neglected, zoonotic disease circulating almost exclusively within African borders to sexually transmitted infection (STI) of international concern. Although phylogenetic evidence suggests progressive evolution from the strain associated with the 2018 outbreak in Nigeria, epidemiological links with previous cases have still not been completely elucidated. Clinically, mpox presents with systemic symptoms, such as fever, headache, malaise and a characteristic cutaneous eruption, similar to that of cognate viruses (e.g. smallpox). Mpox pseudopustules evolve through several stages, including umbilication and crusting, and resolve in the span of 2-3 weeks. The hallmarks that set the 2022 outbreak apart from classic mpox were a disproportionate number of cases occurring in men who have sex with men, an often localized cutaneous picture and a significant burden in terms of concomitant STIs. Investigations into the disease pathogenesis, related immune response, clinical and dermoscopic features, in addition to studies aimed at defining novel management strategies, have advanced mpox knowledge considerably. Herein, recent findings on mpox are reviewed, with a keen focus on dermatological manifestations and their implications in the current diagnostic scenario, reinforcing the pivotal role of dermatologists in managing suspect cases and preventing further spread of the contagion.