An outbreak in Africa of mpox, the disease formerly known as monkeypox, resembles the early days of HIV, scientists have said, as the World Health Organization declared it a public health emergency. The declaration must accelerate access to testing, vaccines and therapeutic drugs in the affected areas, medical experts urged, and kickstart campaigns to reduce stigma surrounding the virus. More resources for research were also vital, they said, with “massive unknowns” about a new variant spreading between people in the Democratic Republic of the Congo. As of 4 August, there had been 38,465 cases of mpox and 1,456 deaths in Africa since January 2022, including more than 14,000 cases and 524 deaths in the DRC alone this year. These included clades I and II of the virus, as well as a new type, clade Ib – an offshoot of clade I, which appears to be driving the outbreak in the DRC and neighbouring countries, and to which children appear particularly vulnerable. The World Health Organization said the outbreak was serious enough to declare a “public health emergency of international concern”, the category used in the past for Ebola outbreaks, Covid-19 and a 2022 mpox surge in Europe. Tedros Adhanom Ghebreyesus, the director general of the WHO, said the situation was “very worrying” and warranted the “highest level of alarm under international health law”. He highlighted the emergence of clade Ib in the east of the DRC and its detection in neighbouring countries. The WHO has released $1.5m from its contingency fund and plans to release more, he said, calling for donors to step up to fund the rest of the $15m needed for its efforts in the region. Trudie Lang, a professor of global health research at Oxford University, said: “I have heard so many people refer to this as being very similar to the early days of HIV.” She said this was particularly the case because the virus appeared to be spreading via sexual networks, with “vulnerable, young, exploited sex workers” at high risk. A “high level of stigma” would require public health campaigns to ensure people understood and sought treatment. While data has yet to be analysed and published, Lang said the frontline teams she spoke to reported a high number of pregnancy losses due to the virus, and babies being born with mpox lesions due to transmission in the womb. There were “massive unknowns”, she said, including the number of cases outside hospitals. Lang said: “What I’m truly worried about is the amount of cases that are not severe. If people have got a more mild infection that is potentially hidden, especially if it’s a sexually transmitted genital infection, they can be walking around with it. “The big question that we’ve got is when is it most infectious, and when is it being transmitted?” Lang added that if the virus arrived in Europe or the US, it would probably be easily contained with vaccination, as in the 2022 mpox outbreak. “What worries me is that that will happen very fast in Europe, but not […] in these really impoverished areas in Africa.” Dr Ayoade Alakija, the chair of Africa Vaccine Delivery Alliance and of the diagnostics non-profit organisation Find, said if the outbreak was in Europe, mpox would have already been considered a major international health emergency. The declaration, she said, “should focus minds and loosen purse strings so that the response recovers from a sluggish start”. “There is an urgent need for more in-depth investigation to better understand mpox transmission dynamics to guide controls and response plans, as well as enhanced surveillance and equitable access to vaccines, diagnostics and treatments for all affected populations. Most vaccines and treatments have been pre-ordered by rich countries and as yet only one diagnostic test exists,” said Alakija. “Without fair access to testing, it is also unclear how viruses like HIV may impact the severity and transmission of mpox. Not focusing on tackling the virus in the DRC has led almost inevitably to spillover to neighbouring countries and the longer action is delayed, the more likely it will spread in Africa and beyond.” The public health agency Africa Centres for Disease Control and Prevention (Africa CDC) had already announced on Tuesday that mpox was a public health emergency. Dr Jean Kaseya, the organisation’s director general, said the declaration was “not merely a formality” but “a clarion call to action” and warranted proactive and aggressive efforts to contain and eliminate the virus. Responding to that announcement, Dr Boghuma Titanji, an assistant professor of medicine at Emory University in Atlanta in the US, said she hoped the declaration would prompt African governments to allocate funds to fight the outbreak. The African Union approved $10.4m (£8m) for Africa CDC’s response at the beginning of August, but Kaseya has suggested the continent will need about $4bn.