Genomic, virologic, and epidemiologic surveillance to track intrafamilial Mpox, Brazil

Mpox expanded globally in 2022, but pediatric and household transmission remains poorly defined. We report a fatal infection in an immunocompromised patient with advanced HIV/AIDS during the epidemic in Brazil. Integrated clinical and genomic investigations revealed intrafamilial spread within a multigenerational household, including a 3-year-old child who had no direct contact with the index case. Viral genomes clustered in lineage B.1.9, and neutralizing antibodies were detected in an older woman and domestic animals. These findings highlight the potential for household transmission beyond recognized risk groups and underscore the need for strengthened surveillance.