Monkeypox in the population

In mid-May, alarm bells began to ring among public health practitioners in a number of countries when they noticed a sudden spike in cases of the rare disease monkeypox. Caused by a close relative of the smallpox virus, it’s normally found only in a handful of African countries where it’s naturally an infection of small mammals like rats and squirrels. In this respect, monkeypox is a misnomer: monkeys are only an accidental victim, like we occasionally are. People who catch the disease, usually after contact with an infected animal, often present with a high fever, swollen glands, muscle aches and weakness, and a pustular blistering rash. So why are lots of cases abruptly cropping up among men in western countries with no travel history to parts of the world where the disease is endemic? What’s changed? So far 2000 cases have been found across 40 countries, and one person has died. Michael Head is a global health researcher at the University of Southampton..

Michael - So, this Monkeypox outbreak is not like any Monkeypox outbreak we've seen before. Usually, they've been quite small in number and have been restricted to the parts of Sub-Saharan Africa that you mentioned, particularly Nigeria and Ghana, or sometimes the Democratic Republic of Congo. Here, the index case, that first case of this outbreak, will almost certainly have had a travel history with those parts of the world. We may or may not have detected the index case here and maybe it went under the radar, but it's almost certain that it will have come from that part of the world and that it will have brought the Monkeypox infection with them. With these cases that have been reported over the last few weeks, they are almost all, if not actually all, linked to these sexual networks amongst men who have sex with men and the transmission has taken place within those networks. We know that Monkeypox spreads predominantly via skin to skin contact. Well, it's very, very close contact. So, it's presumably the case that the rashes and the blisters that we see typically present with Monkeypox, as they appear on the skin, that will have been the mode of transmission from one person to another. So far, the wider community has not been impacted. So it's very, very different to, for example, Covid, which of course is a respiratory infection where everyone is at risk around an infectious person. But with Monkeypox, you do need that close contact. And within these sexual networks, there has been that close contact enough to transmit it initially, and then to sustain transmission across a few countries.

Julia - So we're seeing these cases of Monkeypox increasing, but we've had imported cases in the past before. So why is it now that these cases are taking hold?

Michael - So there will be a combination of several different factors that are combining here to create an outbreak that appears to be sustaining for at least a little while. One of that is population mixing as a result of restrictions being lifted from the pandemic that we've seen over the last two years. Populations are starting to mix in greater numbers. And if you introduce one infection into that community, you then provide opportunities to transmit further. As we have seen within these sexual networks, specifically with Monkeypox, we know that the smallpox vaccine does provide some level of protection against Monkeypox. Now, the smallpox vaccine was used routinely in decades previous across the globe, but it's not been used routinely for many years now. So it might well be that we're seeing a reduction in population levels of immunity against smallpox, which is therefore translating into reduced immunity to Monkeypox as well. And if there are, again, encounters between humans and animals to create that initial infection, then the population mixing might mean further cases beyond the index case. So there's a few factors like that that are combining to create outbreaks. Like we're seeing here with Monkeypox.

Julia - Now we've been seeing this increased transmission, what is being done to contain it?

Michael - So the key aspect of this will be the contact tracing by the public health teams to find contacts of cases and people who might be at high risk of infection. And that is a little bit of a tricky job here, because we do want to highlight the problem to those high risk populations, who are these gay sexual networks, but also we don't wish to stigmatize them. So it does pose a little bit of a problem for the public health teams. And of course the media and people who have to report on it, but we do want people to come forward. The sexual health teams who are dealing with this are extremely expert at doing so. So, actually, within this particular population, with a population that's probably used to being contacted about possible outbreaks, and certainly a public health level of expertise is used to addressing these problems as well. So that contact tracing will be crucial to reduce the number of new cases, to highlight the transmission, and where the risk areas are, and ultimately to slow down the outbreak and eventually bring it to a close.

Julia - And now that we're seeing these cases here, do we think that Monkeypox could become endemic in other countries like the UK? So if it got into these small mammals that normally carry the disease, could it then just become a disease that's in the background here in the UK?

Michael - That is a concern, yes. We certainly don't know if that will happen, or even if it's likely to happen. But it's something that the public health teams, the global health teams, will need to keep a very close eye on, to see if it does become endemic in our rodent populations, for example, or in any other small animals. It could happen. It may or may not happen. There's a lot we don't know about Monkeypox because there's been so few cases, generally speaking, across the world, and certainly few cases in Europe or North America, or other westernised parts of the world. So, again, a bit like Covid, it's a crash course in learning about an infectious disease as the outbreak happens. So only time will tell on that.