How Mpox Spreads: Rural vs Urban Settings

A recent study examining the genetic diversity of the mpox virus (MPXV) in the Democratic Republic of the Congo (DRC) from 2018 to 2024, reveals important insights into how the virus spreads in different regions. Researchers analyzed 603 samples from 581 patients across 17 provinces in the DRC, focusing on the genetic differences in the virus strains. They were able to obtain high-quality genomes for 348 of these samples, uncovering two main patterns in viral spread.

The team found that 95 percent of mpox strains belonged to clade Ia, which is typically linked to infections that spill over from animals to humans in rural, endemic areas. In these regions, several genetically distinct strains within clade Ia circulated simultaneously, suggesting that repeated introductions from animal sources are common. The study also noted that multiple strains often spread in the same geographic areas within short periods, supporting the idea of frequent animal-to-human transmission events.

However, the eastern DRC showed a different pattern, with cases in 2024 linked to a new subtype called clade Ib. This clade Ib strain, identified in the South Kivu province, showed less genetic diversity and appears to spread mainly through human-to-human contact, especially in clusters linked to sexual contact.

The study also looked at specific mutations related to human adaptation, known as APOBEC3-mediated mutations, which are common in viruses that spread between people. Clade Ia strains showed low levels of these mutations, indicating mostly animal-to-human transmission. Clade Ib, however, showed more of these mutations, further supporting its human-to-human spread.

The study authors emphasize the importance of a coordinated health response to manage these diverse transmission patterns and prevent further spread within the DRC and beyond.