#18,588
Less than 3 years ago Mpox was confined almost exclusively to central and west Africa - with only a handful of exported cases - and consisted of two clade (I & II). Clade II, which was found primarily in the DRC, was the more severe of the two.
But for years researchers have warned that the Monkeypox virus was becoming more transmissible, and it had the ability to mutate into a more dangerous variant.
A 2016 study (see EID Journal: Extended H-2-H Transmission during a Monkeypox Outbreak) looked at a large 2013 outbreak of Monkeypox in the DRC and suggested that the virus's epidemiological characteristics may be changing (possibly due to the waning smallpox vaccine derived immunity in the community).
The DRC had reported a 600% increase in cases over both 2011, and 2012. The authors also cite a higher attack rate, longer chains of infection, and more pronounced community spread than have earlier reports.
Like all viruses, Monkeypox continues to evolve and diversify, as discussed in the 2014 EID Journal article Genomic Variability of Monkeypox Virus among Humans, Democratic Republic of the Congo, where the authors cautioned:
Small genetic changes could favor adaptation to a human host, and this potential is greatest for pathogens with moderate transmission rates (such as MPXV) (40). The ability to spread rapidly and efficiently from human to human could enhance spread by travelers to new regions.
And in the spring of 2022, a new clade IIb began spreading internationally, forcing the WHO to declare a PHEIC (Public Health Emergency of International Concern). While that outbreak slowed over time, at least 100,000 cases were reported outside of Africa.
In mid-August of 2024 the WHO declared the Mpox outbreak in Central Africa to constitute a PHEIC after reports that clade (Ib) of the virus had begun to spread outside of the DRC (see More African Nations Reporting Mpox - Africa CDC Mpox Update (Jul 30th)).In late 2023 another - more formidable - clade Ib clade emerged (see Preprint: Sustained Human Outbreak of a New MPXV Clade I Lineage in Eastern Democratic Republic of the Congo), that was reported to be more transmissible, and potentially more severe.
Today, there are 4 officially recognized clades of the Mpox virus (Ia, Ib, II, IIb), and more could emerge over time. A reminder of what can happen when an emerging virus is allowed to simmer for years without serious interventions.
Last month the WHO published a new, updated risk assessment, which puts the risk of national and international spread of clade Ib as HIGH and Ia, II, and IIb as MODERATE.
So far, at least 11 non-African nations have reported imported clade IIb cases over the past 6 months.
Highlights
• The outbreak of mpox due to clade Ib monkeypox virus (MPXV) continues predominantly in the Democratic Republic of the Congo, Burundi and Uganda, with new travel-related cases identified in previously unaffected countries.
• The Democratic Republic of the Congo remains the most affected country, experiencing circulation of both clade I MPXV subclades. Despite many of the provinces reporting stable trends in cases, the situation in the country remains concerning, with continued sustained circulation of virus strains. The escalating violence in the eastern part of the country poses additional challenges for the mpox response.
• Burundi and Uganda continue to report the most cases outside of the Democratic Republic of the Congo.
• New travel-related cases of mpox due to clade Ib MPXV have been detected in countries that had already detected travel-related cases before, including China, Germany, Thailand, the United Kingdom of Great Britain and Northern Ireland and the United States of America.
• Azerbaijan has reported its first case of mpox. Information on the MPXV clade is not yet available.
In a separate document issued earlier this week, the WHO released a Risk Assessment on the clade Ia Mpox virus (which has not spread internationally). While confidence is limited (low to moderate), right now it doesn't appear to pose as big of risk to the international community as clade Ib.
As our collective immunity from the smallpox vaccine - which was discontinued in the late 1970s - wanes, there will be increased opportunities for emerging pox viruses to make a comeback. We ignore them at considerable risk to global public health.
Alaska Health Department Announces A Fatal Alaskapox Infection
A Newly Discovered Poxvirus Detected In Reindeer in Sweden & Norway
EID Journal: Novel Poxvirus in Proliferative Lesions of Wild Rodents in East-Central Texas, USA
A Novel Zoonotic Orthopoxvirus Resurfaces In Alaska
