Reports of people infected with the Mpox virus are once again on the rise in Europe. Immunologist Andreas Bergthaler talks about its transmission, treatment and the risk for a future epidemic or even pandemic. In this interview, the researcher at MedUni Vienna and CeMM - Research Center for Molecular Medicine of the Austrian Academy of Sciences (ÖAW) shares what we currently know about the Mpox virus.
What do we know about Mpox so far?
Andreas Bergthaler: It was discovered in the 1950s in a colony of monkeys in Denmark, which were kept there for research purposes at the time. Hence the name, which is actually a misnomer because the disease actually occurs in rodents in Africa, among other places. In the 1970s, it was shown that humans can also contract the disease and that the disease can be transmitted from animal to human as well as from human to human. Mpox is endemic in Africa. At the same time, cases and smaller clusters have repeatedly emerged in Europe and the US in recent decades - often in connection with travel or animal transportation.
Mpox instead of monkeypox
Until recently, the disease was still called monkeypox. Why was it renamed Mpox?
Bergthaler: In November 2022, the World Health Organization (WHO) recommended changing the English name “monkeypox” to “Mpox”. The term “monkeypox” for a viral disease that mainly occurs in Africa can be perceived as racist. Since then, we have been talking about Mpox.
Cases have already emerged in Europe in 2022.Now outbreaks have been reported again in African countries.What has happened since then?
Bergthaler: The Mpox virus has continued to change and there are various outbreaks caused by strain I Mpox viruses in 2024. Mpox viruses have been endemic in countries such as the Democratic Republic of Congo (DR Congo) for decades. However, a distinction must be made between two different genetic strains: virus strain I, also known as clade I, and strain II, or clade II. The 2022 outbreak was caused by Mpox viruses of virus strain II, which causes significantly milder courses than strain I. Since 2023, there has been a major outbreak of Mpox viruses of virus strain I in the DR Congo with over 20,000 suspected cases and more than 1,200 deaths. This is currently circulating not only in the DR Congo, but also in neighbouring countries.
This is the reason why the WHO declared a 'public health emergency of international concern' for the current Mpox outbreak on August 14. This heightened alert level enables the affected countries to intensify their protective measures and free up international resources to fight the virus, for example through the availability of vaccines.
And how dangerous is the situation in Europe?
Bergthaler: The first case in Europe was identified in Sweden this summer. It occurred in connection with travel to affected African countries. Further sporadic cases can therefore also be expected in Europe. However, the severity of the disease, which is also triggered by the currently circulating virus strain I, is heavily dependent on the health standards and medical facilities in a country. For Europe, Pamela Rendi-Wagner, Director of the European Center for Disease Prevention and Control, has classified the current risk as “low”.
Covid vs. Mpox
What distinguishes Mpox viruses from coronaviruses?
Bergthaler: They differ in many fundamental characteristics. The most important characteristic is that smallpox viruses have a DNA genome and coronaviruses or influenza pathogens have an RNA genome. The copying machines, i.e. the polymerases of RNA viruses, are significantly more error-prone than DNA viruses. This means that around 2 to 6 mutations per year are observed in smallpox viruses, compared to an average of 25 in Sars-CoV-2. And: the evolution of these smallpox viruses is significantly slower. On the one hand, this makes it more difficult to trace the transmission routes by sequencing. On the other hand, it is therefore unlikely that these viruses are constantly changing as quickly as Sars-CoV-2. Overall, it can be assumed that the virus is slower in its evolution.
How can you become infected with Mpox and what are the symptoms?
Bergthaler: You can become infected from infected animals through a bite or through direct contact with body fluids. In humans, it is mainly these skin rashes, i.e. the typical smallpox, that are infectious. In addition, in many current cases these lesions are primarily found in the mouth and genital area. Basically, droplets are also a possibility of infection because saliva is also infectious. However, direct physical contact is much more important. You can protect yourself by avoiding close physical contact with suspected cases. The virus also circulates in wild animals, so contact with and consumption of wild animals in the affected countries in Africa poses a further potential risk.
In addition to skin rashes, an Mpox infection causes general characteristics of infections such as fever, headaches and fatigue. Lymph nodes also swell up.
Medication and vaccinations
Are there medications or vaccinations that protect against the disease?
Bergthaler: On the one hand, there is a drug - called Tecovirimat - that is approved for the treatment of Mpox. However, current data from a study in the DR Congo show that this drug is probably not effective enough against Mpox viruses of the clade I strain.
On the other hand, there are smallpox virus vaccines that are effective both preventively and in the first few days after an infection. A review that summarized several field studies found a protective effect of over 85 percent. These Mpox vaccines, which are based on the principle of attenuated cowpox viruses, are approved in the EU and are also available in Austria. General vaccination is not recommended by the WHO. The National Vaccination Committee recommends Mpox vaccination for special groups of people who are in close contact with infected persons or for medical personnel who are at high risk of coming into contact with infected persons or infectious samples.
