No, we don’t have to worry about the monkeypox virus engulfing our regions. But we must be vigilant: the virus must not enter the world of our rodents.
Most people can’t hear the word ‘corona’ anymore, but the pandemic has slashed it so hard that the fear of viruses runs deep. Certainly because it is regularly pointed out that the risk of virus attacks from the animal world remains real, as a result of globalization and our ill-considered handling of our living environment. Moreover, global warming will encourage the transfer of viruses to humans.
That fear may explain the great suspicion with which the monkeypox virus is viewed as it modestly rears its head in Europe and the US. A handful of people in our country have also become infected with the virus, which manifests itself strikingly through thick blisters on the skin. All in all it is quite harmless: usually a person heals on its own. The chance of death is small.
Nevertheless, the sudden appearance of the virus outside its ‘normal’ habitat (West and Central Africa) is causing some concern among virologists. Any virus that behaves differently than expected is followed closely. Especially because the monkeypox virus is related to ‘our’ smallpox virus, which could wreak havoc in a human population with a mortality of more than 30 percent. Thanks to good vaccines and efficient vaccination campaigns, it could be eradicated almost half a century ago.
Virologists believe that the virus could take the place of the eradicated smallpox virus from humans.
As a result, vaccination campaigns were also stopped, causing people’s resistance to smallpox viruses to steadily decrease – resistance to the disappearing virus partly remained intact against the current one. Some virologists believe that monkeypox virus could take the place of the eradicated virus. Especially because viruses have the ability to adapt to new hosts. In addition, they can become more virulent and – if necessary – more deadly over time.
DNA-virus
‘Unlike, for example, coronaviruses, the genetic material of pox viruses is not packaged in RNA, but in DNA,’ says Laurens Liesenborghs, a doctor at the Institute of Tropical Medicine (ITM). ‘DNA viruses are less able to change than RNA viruses, which makes their adaptation to new hosts less easy. It is somewhat disturbing that the monkeypox virus has managed to jump from one human to another on its own, without involving another animal. That is thought provoking.’
Liesenborghs is an expert in monkey pox viruses. He is investigating outbreaks in Congo. There, people are usually infected after contact with infected animals, who catch them and prepare them for the pot. Most infected people live in remote villages, where they have little chance of infecting others. But the situation is different with the West African variant of the virus. This mainly circulates in Nigeria, where people travel more, including abroad. It is likely that the cases of monkeypox virus registered with us originate from there. Fortunately, that variant is a lot milder than the Congolese.
‘Intense direct skin contact between people would be the way the virus spreads in us. That’s new’, says Liesenborghs. ‘The incident illustrates the importance of good monitoring and, if possible, rapid treatment of viral outbreaks, even in remote regions. We should therefore not only help people in Congo so that they themselves are less affected by the consequences of such infections. We also have to work there as a vanguard, to avoid systematic invasions of novelties. The fight against viruses must be waged on the world stage.’
The large-scale replacement of forests by plantations increases the chance that viruses will transfer from other animals to humans.
By the way, the name ‘monkeypox virus’ is not well chosen. The virus was first described in 1958 after monkeys became ill from it in a Danish laboratory. However, it is mainly found in rodents. Monkeys get sick just like us, but differently from us. In 2020, researchers in Nature Microbiology known that the virus was circulating in a group of chimpanzees in a sanctuary in Côte d’Ivoire. The animals mainly suffered from respiratory problems as a result of the infection. It is not clear whether infected rodents are affected by the virus.
‘In laboratory conditions we mainly find smallpox blisters on the tongue and eyelids of infected rodents, but they have never been seen in the wild,’ says biologist Herwig Leirs (UAntwerp), a rodent specialist who, together with Liesenborghs, has set up a project to to monitor viruses in rodents on a large scale. ‘It is of course possible that wild infected animals die quickly so we don’t get to see them. But it is clear that the potential reservoir for monkeypoxviruses in nature can be large.’
Infected prairie dogs
The monkeypox virus has already been found in African squirrels, dormice, rats and shrews. It has been described how the importation of infected African rodents for a US pet chain in 2003 led to the contamination of local prairie dogs that were also for sale – prairie dogs are marmot-like relatives of our squirrels. No fewer than 47 people became infected with the virus through their purchased prairie dogs, but they all survived.
Some virologists are warning that we absolutely must avoid the monkeypox virus getting to us in squirrels and other rodents, which could quickly spread it across our continent. ‘I understand the concern,’ says Leirs, ‘but there is no reason to worry. We must, of course, remain vigilant. We have animal species in Europe that are related to the species that form the main virus reservoirs in Africa. We also don’t know how susceptible pets like hamsters and guinea pigs are to the virus. We have to keep a close eye on such matters.’
How could such an imported virus from humans end up in natural rodent populations? ‘We don’t know,’ admits Leirs. ‘We don’t even know much about how it spreads from person to person. Can it be passed on through bedding, or through feces? Because that way it could exceptionally reach other animals. In the corona story we have seen that infected people can pass the virus on to farmed minks. If a virus can jump from rodents to monkeys and humans, we must assume that the opposite is also possible.’
In general, Leirs warns of the dangers of extensive deforestation and other attacks on our environment, which promote contact between people and other animals. ‘The large-scale replacement of forests by plantations increases the chance that viruses will transfer from other animals to humans. Certainly if there is no form of immunity against a virus, it can spread quickly in the human world. It is therefore in our interest to treat our environment, and especially that of other animals, with more care than is currently the case.’