Mpox cases are surging in the Democratic Republic of the Congo and several of its neighbouring countries. and more than 500 deaths, already exceeding its 2023 total, which itself was a record. Other infections can cause lingering complications, such as long covid, which can occur even after mild bouts of covid-19. So, is this a risk with mpox?
Mpox, formerly known as monkeypox, commonly causes a rash that develops into blisters, as well as aches, pain, fever and fatigue, which usually begin within a week of infection and last for two to four weeks. A great deal of research has been done into conditions like long covid, , but few scientists have studied mpox’s lasting effects
Efforts were made amid the 2022 mpox outbreak, when it was first declared a global public health emergency, as cases spread on continents like Europe and North America for the first time. But that variant of the virus, called clade IIb, is different to the one driving the current emergency, clade Ib, which was only identified in September 2023 and so has no long-term studies into its potential effects.
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at the University of Rwanda has been studying the unfolding situation since March. So far, any lingering symptoms seem to be temporary. Complaints of fatigue and pain stop within a couple of weeks, he says. But Udahemuka is only following 200 people and, given the extent of mpox’s spread, we can’t rule out others being more badly affected.
For instance, post-viral fatigue, when the lethargy that starts during an infection continues after it has gone, is among the most common symptoms of long covid, sometimes persisting for years. There is no reason to think mpox should be different, according to Udahemuka and at the Institute of Tropical Medicine in Antwerp, Belgium.
As clade Ib research is limited, some scientists are looking at clade IIb for clues. The similarities between the two variants’ initial symptoms suggests that any prolonged symptoms would also be similar, says Van Dijck.
He and his colleagues have followed 119 people in Antwerp after they caught mpox in 2022. The results, which haven’t yet been published, suggest that around a fifth of them had fatigue before mpox, which increased to a quarter eight months after the infection and had only returned to pre-infection levels by 16 months later.
Scarring also seems to be common with clade IIb, but the proportion of people this affects varies hugely, from just over to more than . This variation is probably due to the small numbers of people in these studies, as well as differences in their ages and overall health, says Van Dijck. In his study of 119 people in Antwerp, 14 per cent had scars on their face, hands or genitals just over a year after their infection.
That may be one of the reasons why symptoms of anxiety and depression can also occur after mpox, says at University College London. “People report that they are conscious of having their scars and they are consciously changing their clothing or finding ways to hide the scars,” says Van Dijck, whose team found that symptoms of anxiety and depression rose by around 7 per cent in the eight months after an infection, but then didn’t persist for much longer.
Mpox may also cause these symptoms by directly affecting the brain, says Witzel. Emerging evidence suggests , with reports of confusion and memory loss, on top of common symptoms like headaches. “The virus has been isolated in different types of samples – semen, breast milk and so on,” says Udahemuka. “So, probably it can also reach that part of the body.”
But not everyone is convinced. “Mpox seems to have very limited impact on the brain,” says Van Dijck. Brain swelling, for example, is rare, he says. Lingering mental health symptoms could just be the result of people having to isolate or endure the stigma of mpox, says Witzel.
These results help point us in the right direction, but only time will tell whether clade Ib specifically has lasting complications – or even more serious ones than we have seen with mpox before. Clade I is more dangerous than clade II and “generally, the more severe an illness is, the more severe the long-term issues”, says Witzel.
