The two distinct clades or variants of the virus were named Congo Basin (Central Africa) and West African clades, after the two regions to which they are endemic. But on Friday, the WHO changed the names of the groups to clade I and clade II respectively, to avoid the risk of geographic stigmatization. It also announced that clade II had two subclades, IIa and IIb, with viruses within the latter identified as being responsible for the current global outbreak.
The UN health agency specified that clades IIa and IIb are related and share a recent common ancestor, therefore IIb is not a branch of IIa. Clade IIb contains viruses collected in the 1970s and from 2017. “Looking at the genome, you see some genetic differences between the viruses in the current outbreak and the old clade IIb viruses,” declared the WHO.
“However, nothing is known about the relevance of these genetic changes, and research is ongoing to determine the effects (if any) of these mutations on disease transmission and severity,” it added.
In addition, “it is still early, both in the outbreak and in laboratory studies, to know if the increase in infections is due to the observed changes in the genotype of the virus or to host factors in humans”.
International public health emergency
The outbreak of monkeypox infections began to be reported in May outside of endemic countries in Africa. The WHO declared it an international public health emergency on July 23.
More than 35,000 cases in 92 countries with 12 deaths have been reported to the WHO. Almost all of the new cases are reported in Europe and the Americas, and experts have studied samples of those cases.
“Diversity among the viruses responsible for the current outbreak is minimal, and there are no obvious genotypic differences among viruses from non-endemic countries,” the WHO explained.
A new name
Meanwhile, the WHO said its plan to change the name to monkeypox would take “months”. The entity has expressed concern about the name, which experts consider misleading.
The name monkeypox comes from the fact that the virus was originally identified in monkeys used for research in Denmark in 1958. However, the disease is most often found in rodents, and the current outbreak is human-to-human transmission. The WHO has asked for help from the public to define a new name, with a web page where anyone can make suggestions.