Reports show how mpox clade 1b spreads through non-sexual contact in DR Congo, Ireland
December 19, 2025
New evidence from the Democratic Republic of the Congo and Ireland underscores a critical shift in mpox clade 1b transmission. In Uvira, household spread, not sexual contact, drove infections, disproportionately affecting children living in crowded, resource-limited settings. Infant mortality, while lower than in clade 1a outbreaks, remains alarmingly high. Ireland’s first clade 1b cluster shows the virus can also spread through healthcare and household exposure in high-income countries. Together, these findings challenge narrow risk frameworks and highlight the urgent need for household-focused prevention, vaccination, nutrition support, and sustained global surveillance.
Two new studies published in Eurosurveillance offer a sobering update on the evolving epidemiology of mpox clade 1b, revealing transmission patterns that demand a recalibration of public health strategies. In Uvira, a densely populated city in eastern Democratic Republic of the Congo, researchers documented nearly 1,000 suspected cases over four months, with almost two-thirds occurring in children under 15. Contrary to earlier global narratives, sexual transmission played a limited role. Household exposure, driven by overcrowding and large family sizes, accounted for the majority of infections.
This shift has serious implications. Infants experienced mortality rates more than five times higher than other age groups, highlighting how malnutrition, limited healthcare access, and crowded housing amplify risk. Although clade 1b appears less virulent than clade 1a, its impact on children remains profound. Standard recommendations such as home isolation are often impractical in such settings, reinforcing the need for context-specific interventions. Vaccination, nutritional support, and community-level prevention must move beyond individual risk models and address household realities.
The second report, detailing Ireland’s first clade 1b outbreak, demonstrates that these challenges are not confined to low-resource settings. Four linked cases included sexual, household, and healthcare-associated transmission, with a healthcare worker infected while providing care. Genomic links to a strain detected in Oman underscore the role of international travel in accelerating global spread.
Together, these outbreaks reveal a virus that adapts to social and structural conditions, exploiting gaps in both crowded urban communities and clinical environments. The findings argue strongly for sustained surveillance, rapid diagnostics, and integrated responses that bridge public health, clinical care, and social support systems. Mpox clade 1b is not a localized concern. It is a global threat that requires prevention strategies as adaptable as the virus itself.