Expert comment: Outbreak of new strain of M Pox

“Mpox is a disease that resembles the now extinct smallpox. It is caused by monkeypox virus, a virus typical of rodents that can jump and infect humans. Two types of monkeypox virus have been traditionally identified, the so-called clade I in the Congo basin in Central Africa and clade II in West Africa. Besides their geographical distribution, the two types also differ in their capacity to cause disease and even mortality, estimated to be close to 10% in the case of clade I. 

“In May 2022 Mpox spread from endemic areas in Africa and went global, mostly via close contact facilitated by sexual activities. That outbreak was caused by clade II, arguably the mildest of the two clades. This current outbreak in DRC is caused by a clade I virus that has copied clade II and is transmitting sexually. WHO and African health authorities are hugely concerned about this outbreak, because as a clade I virus it is more aggressive, but also because it appears to have reached other communities such as sexual workers and even children. These are highly interactive communities and hence may facilitate further spread of the virus. In the case of sexual workers, concurrent diseases such as AIDS may result in higher fatality rates. 

“At the moment the outbreak is contained in the South Kivu area, an area historically ravaged by the Congo civil wars and with an extremely vulnerable population, so the public health prospects are really worrying. In addition, the real size of the outbreak remains unclear and undetected cases may be circulating beyond this area and into neighbouring countries like Rwanda or Burundi. It remains unclear what is driving monkeypox virus to jump into humans and to spread human to human via sexual transmission. 

“The disease has been endemic in Africa for decades with sporadic cases caused by direct contact with infected animals. However, over the last 10 years a steady increase in Mpox cases including several outbreaks affecting hundreds has been reported. Whilst this coincides with a decline in the global herd immunity against poxviruses that followed the worldwide vaccination campaign 40-50 years ago, it is likely that additional factors are playing a role in the emergence of this once-obscure human disease. 

“Interestingly, the new monkeypox virus appears to have a mutational pattern similar to that observed in the 2022 Mpox outbreak, perhaps suggesting a similar evolutionary trend. Elucidating this gap of knowledge is critical to understand why Mpox is on the move and what may happen in the future.”