An unusual accumulation of cases of monkeypox is puzzling physicians. In the last week alone, 120 infections with this more harmless relative of the smallpox virus were reported in Europe and North America – including some in Germany.
The current outbreaks therefore include more cases outside of Africa than in the entire period since 1970. The cause of this accumulation is so far unclear, because this virus is actually difficult to transmit.
Smallpox has been eradicated since 1980 thanks to a worldwide vaccination campaign. The last samples of the pathogen Orthopoxvirus variolae only exist in high-security laboratories in Russia and the USA. However, this is different with relatives of this smallpox virus, which are still found in the animal kingdom today – including cows, horses, rodents and, more recently, European squirrels.
One of these animal pox pathogens is the monkeypox virus (MPV), which is currently causing a stir around the world. This virus was first discovered and described in infected laboratory monkeys in 1958, but its primary hosts are actually rodents.
The monkeypox virus has long been widespread and native to West and Central Africa. In 1970, the first case of monkeypox in humans became known there – a small child had become infected.
Typical symptoms are initially flu-like symptoms such as fever, headache and body aches. A few days later, blistering skin pustules develop, which scab over after a while and the crust then falls off.
In the milder West African variant, the remaining symptoms usually subside on their own after a few weeks. However, the Central African variant can lead to severe courses, especially in children, and is fatal in around eleven percent.
Small outbreaks of monkeypox usually occur in Africa, but these remain localized and usually end quickly. Because unlike influenza or Sars-CoV-2, the monkeypox virus cannot be transmitted by aerosols or droplet infection.
An infection from person to person is therefore less common and only possible through direct contact with skin pustules, scabs or body fluids.
Monkeypox cases outside of Africa have been correspondingly rare. Most were individual travelers who had been infected in Africa and then returned to their home countries. In 2003, there was also a smaller outbreak in the USA due to an import of infected rodents, which mainly infected pet dealers and pet buyers.
The current accumulation of monkeypox cases, especially in Europe and North America, is all the more unusual: in the last week alone, 120 cases of monkeypox were reported in eleven countries outside of Africa.
That’s more non-African cases than has been known in all the time since 1970. In Germany, too, there are already four confirmed monkeypox infections and several other suspected cases.
Also unusual: unlike in the past, the infected were not in Africa before or had contact with potentially infected animals. “This is the first time that chains of infection with no known connection to West or Central Africa have been observed in Europe, reports the European disease agency ECDC. Instead, there appear to be several small outbreak hotspots where local human-to-human transmission appears to have occurred.
“It is very unusual to see such community transmission in Europe,” said Charlotte Hammer, an epidemiologist at the University of Cambridge.
The increasing number of cases of monkeypox, for which no end is in sight, is also a source of concern. “Due to the diverse contacts of those currently infected, further diseases are to be expected in Europe and also in Germany,” said a report by the Federal Ministry of Health. So far, both the chains of infection and the transmission routes have only been partially clarified, as experts report.
“Monkeypox outbreaks continue to escalate and this is undoubtedly of concern,” says Michael Head of the University of Southampton. After all, the first genome analyzes show that the diseases are caused by the West African monkeypox virus.
This triggers significantly milder infections than the Central African variant. However, because only individual samples have been examined so far, it is still unclear whether and how the individual outbreaks are linked.
It is also unclear whether the increased outbreaks are due to a change in the monkeypox virus. Theoretically, it would be conceivable that a mutation would facilitate human-to-human transmission of the pathogen. This could explain why new outbreaks are also emerging outside of Africa.
However: Unlike the very adaptable and mutating coronavirus, smallpox viruses are large DNA viruses that mutate only slowly. It is therefore rather unlikely that the monkeypox virus suddenly mutated, comments epidemiologist Raina MacIntyre from the University of New South Wales in “nature news”.
The researchers hope to get more information when more samples have been sequenced and the chains of infection have been elucidated.
After all, everything indicates that monkeypox still seems to be transmittable only through direct physical contact or contact with the smallpox scab that has fallen off. “It is therefore important to underline that even a large monkeypox outbreak is very different from the Covid-19 pandemic,” said Head.
Caution is primarily required in direct contact with sick patients and their skin pustules. The virus can also be transmitted during sex.
If the outbreaks continue to increase, it is also possible to vaccinate against them. Because the vaccines against smallpox are also effective against the monkeypox virus. Both in Europe and in the USA there are stocks of such smallpox vaccines that can be used for a ring vaccination if necessary.
Only people in the vicinity of sick patients are vaccinated to prevent the virus from spreading further. Unlike the easily transmissible Sars-CoV-2 coronavirus, this strategy is usually sufficient for outbreaks of less contagious pathogens.
Quelle: Robert-Koch-Institut (RKI), nature, European Centre for Disease Prevention and Control (ECDC), Science Media Centre
This article was written by Nadja Podbregar
The original of this article “Experts are puzzled as to why monkeypox cases are increasing” comes from scinexx.
