Monkeypox is a viral illness related to smallpox. Until May 2022, it was mainly known to strike in West Africa and the Congo, but as of this month cases have spread rather rapidly (within a few days) around the Western world. On 17 May, it was reported that 17 cases had been reported in Britain. The day after that, I saw cases had been reported in Spain and Portugal. The day after that, I saw cases had been reported in the US, and as of the day of my writing this (20 May) cases have also been reported in Canada and Australia.

Symptoms of monkeypox include fever, aches, chills, swollen lymph notes, exhaustion, and a characteristic rash with bulbous sores, a bit like chickenpox or syphilis. These sores scab over before they fall off. Illness caused by monkeypox can last for weeks.

Infection is thought to be caused by large respiratory droplets, or by other sharing of bodily fluids (some of the transmission in this outbreak seems to have occurred during sex, for example). If it is true that transmission is largely droplet-based, then measures such as mask-wearing, social distancing and regular hand sanitising (it’s thought that soap and hot water is not adequate) should prove effective. Of course, the same thing was said about Covid-19, which proved to be more infectious, with aerosol-based transmission, than that. Monkeypox is not thought to be as infectious as Covid. In fact, before the current outbreak, it was not thought to be very infectious at all, but it’s spread so suspiciously fast I’m not sure we can be confident it hasn’t evolved. The incubation period is supposed to be 5–21 days (so pretty long).

In Africa, the virus is thought mainly to circulate among rodent populations, only occasionally crossing the divide into infecting humans. The Congolese variant is estimated to have a 10% mortality rate (although you have to take into account that the health systems in that region are heavily struggling and don’t have the resources of other countries). The West African variant – which the 2022 outbreak belongs to – is milder, with a 1% mortality rate in West Africa itself, and zero known fatalities from cases in developed countries (mainly in the US, which had an outbreak in the early 2000s).

There is already an 85% effective vaccine against monkeypox: it’s the smallpox vaccine. There are a couple of issues, though: most countries’ stockpiles are small, because smallpox was eradicated decades ago; and the vaccine has some side effects that make it undesirable for widespread use, anyway. With contact tracing and “ring vaccination” (where you only vaccinate the people who get exposed – this is a vaccine that works as post-exposure prophylaxis) it should still be effective, though. Public health authorities are encouraging people not to be too worried about monkeypox, saying the disease is mild (can’t help but think they mean “mild” in the clinical, “you probably won’t require hospitalisation” sense though) and transmission is mostly restricted to people in close proximity with one another for an extended period, like household members.

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