For years, African scientists tracked a steep rise in monkeypox cases.
More than 2,800 suspected cases were reported in 2018 in the Democratic Republic of the Congo alone. The year after, there were nearly 3,800.
By 2020 — half a century after the first human infection was found in the central African country, then known as Zaire — the total tally of suspected annual cases neared 6,300, including 229 deaths.
The clear spike in infections occurred as globalization increased, humans continued encroaching on animal habitats and cross-protection offered from decades-old smallpox immunization campaigns began to wane. Given that perfect storm, many scientists weren’t shocked by the recent emergence of monkeypox in other countries around the world.
Some also warn that this won’t be the last time the virus spreads beyond its typical territory.
“The recent outbreaks are kind of the culmination of years of warnings that basically went ignored,” said Dr. Boghuma Titanji, a scientist and infectious diseases physician at Emory University in Atlanta who is originally from Cameroon.
“Because unfortunately, monkeypox is a disease that has traditionally caused outbreaks in Africa — and usually in very remote parts of Africa — and affecting populations that the world doesn’t always care about.”
‘Our fears are being confirmed’
The monkeypox virus, known for causing telltale skin lesions, typically enters human populations when someone touches or eats infected wildlife. From there, it can spread through close contact, including respiratory droplets in the air, skin-to-skin contact or if someone touches contaminated surfaces such as clothes or bedding.
Most researchers who study emerging viruses were long concerned it could “evolve to fill the ecological niche” left behind when a similar virus, smallpox, was eradicated through global immunization programs, Titanji told CBC News.
“If given the opportunity to spread unchecked … it could get better at infecting humans and lead to bigger outbreaks than what we’ve seen in the past,” she added.
Human monkeypox incidence “dramatically increased” in rural Congo in the decades after mass smallpox vaccination ceased, researchers warned in a paper published in 2010 in the peer-reviewed journal Proceedings of the National Academy of Sciences.
In Nigeria, more than 500 monkeypox cases have been reported since 2017, including a handful of deaths — and the actual number could be higher, given limited surveillance of the virus’s spread in rural areas, said Dr. Oyewale Tomori, a Nigerian virologist.
“The longer we are away from the smallpox vaccine, the more the likelihood that monkeypox would begin to spread,” said Tomori, a member of the Global Virome Project leadership board and previous president of the Nigerian Academy of Science.
“We’ve been saying that for quite some time. Now our fears are being confirmed.”
Animal migrations driven by climate change and deforestation are also fueling more human-animal interactions, Titanji said, which makes it easier for viruses such as monkeypox to spill over from wildlife into human populations.
“With the world being as interconnected as it is, it takes less than 24 hours for a traveler from an endemic country, like Nigeria, Cameroon or [Congo]to actually get to Europe or North America or South America, or anywhere else on the planet for that matter,” she said.
Spreading out of Africa is not a great surprise, echoed Dr. Beatrice Nguete, a physician and monkeypox researcher with the Kinshasa School of Public Health in Congo’s capital city.
“All communicable diseases have the potential to move out,” she said. “You have one person visiting an endemic [area]or an area where there was an outbreak occurring — you have that possibility.”
Recent surge in global travel
But why now, exactly?
Monkeypox cases have emerged sporadically in other countries before, typically with ties to travel, but not to the scale of the current multi-country outbreak where local transmission is clear.
Hundreds of cases have been reported so far across multiple continents, largely among men, with more than 50 confirmed or suspected infections now under investigation in Canada.
They include a child in Quebecwho attended school after being exposed.
There’s no concrete evidence yet that the virus has mutated, according to World Health Organization (WHO) officials, though global teams are still analyzing samples.
instead, dr David Heymann, a leading adviser to the WHO and former head of its emergencies department, recently suggested that the unprecedented global outbreak was a “random event” and likely tied to transmission at raves held in Europe.
People can sometimes be contagious with monkeypox for close to a month, including a day or so before skin lesions appear — giving the virus lots of time to transmit. That means high case counts in Africa and more mobility after a long travel lull during the COVID-19 pandemic might be providing the ideal conditions for its rapid spread.
“We’re seeing a very big surge in global travels, the likes of which we haven’t seen at any point in time over the last three years,” noted Dr. Abdu Sharkawy, an infectious diseases specialist at the University Health Network and an assistant professor of medicine at the University of Toronto.
Given the unusual nature of current transmission patterns, there’s also a possibility the virus was spreading globally, undetected, for quite some time, until clinicians outside Africa realized what they were seeing, said Dr. Michael Libman, director of the JD MacLean Center for Tropical Medicine at McGill University in Montreal.
“If it has evolved in a certain way, that might make it slightly different than what we’ve dealt with in Africa in the past,” he said.
WHO warns of ‘further transmission’
Lingering questions surrounding the current global outbreak make it tough to predict how it will play out. But monkeypox outbreaks in Africa typically tend to ebb and flow, said Tomori of the Global Virome Project.
“We don’t see rapid transmission like you see with COVID, for example,” he said. “But also it dies down almost within a few months after one or two generations of spread … then suddenly pops up again.”
Officials in Canada, the UK and multiple other countries are also pursuing ring vaccination Strategies to cut off the chains of virus transmission by inoculating certain high-risk individuals — such as close contacts of people with suspected infections — with smallpox shots.
still, dr Hans Henri P. Kluge, the WHO’s regional director for Europe, issued a statement on Tuesday outlining his concern that the “potential for further transmission in Europe and elsewhere over the summer is high,” given the number of large parties and festivals expected in the months ahead.
“As of now, an effective response to monkeypox will not require the same extensive population measures as we needed for COVID-19 because the virus does not spread in the same way,” he continued. “But — and this is important — we do not yet know if we will be able to contain its spread completely.”
Officials from the European Center for Disease Prevention and Control are also warning that if monkeypox spills into local wildlife, it could become endemic to that continentlike in parts of Africa — referring to when a virus is consistently circulating within a specific region.
“If the current trends continue — and there’s no reason to believe they shouldn’t — we’re going to see a lot more cases, and we’re going to see them in a very diverse span of geographical areas,” the U of T’s Sharkawy said.
Given the possibility of ongoing spread and future outbreaks, Titanji of Emory University said it’s crucial that the global public health community pays closer attention to animal-to-human virus transmission, for both monkeypox and other emerging pathogens.
“When these outbreaks across North America and Europe ultimately come to an end, will we go back to ignoring the spillover events that have been happening for the last 50 years in Africa?” she asked.
“Or are we going to invest more meaningfully towards better tracking the virus — and better protecting those populations — to really stop the spillover events at their source?”