Mpox outbreak in Rio de Janeiro, Brazil: A translational approach

Area of Science:

• Epidemiology
• Infectious Diseases
• Virology

Background:

• Mpox, a zoonotic disease, saw global spread in 2022 with sustained human transmission.
• Previous outbreaks outside Africa were limited, raising concerns about the 2022 event's unusual features.

Purpose of the Study:

• To investigate the mpox outbreak in Rio de Janeiro state, Brazil, from June to December 2022.
• To describe the clinical characteristics, demographics, and diagnostic findings of mpox cases.

Main Methods:

• Observational study of suspected mpox cases using public healthcare notification forms.
• Diagnosis confirmed by MPXV-PCR; anti-OPXV IgG determined by ELISA.
• MPXV genome sequencing performed on seven confirmed cases.

Main Results:

• 816 of 3095 suspected cases were confirmed positive for mpox (26.3%).
• Confirmed cases were predominantly men in their 30s, including men who have sex with men (MSM); 34.9% lived with HIV.
• Females and individuals under 18 represented 9.4% and 5.4% of cases, respectively, with distinct clinical presentations.

Conclusions:

• Mpox in Rio de Janeiro presented with diverse, often mild, clinical features, predominantly anogenital lesions.
• Higher incidence in females and children than typically reported warrants attention.
• Observed bimodal distribution of PCR cycle threshold (Ct) values suggests potential need to revise diagnostic criteria for specific groups.