Agrowing number of countries are reporting cases of monkeypox, a rare viral illness typically found in parts of Africa. On May 7th Britain reported a case in a traveller from Nigeria. By May 20th America, Australia, Canada and at least eight European countries had reported dozens of confirmed or suspected cases. Britain reported 11 new cases on May 20th, more than the total in the previous two weeks. Many have no links to African travel, which means they were transmitted locally. In the past sporadic cases were almost always imported. All of this is alarming. But the world is far from helpless.
Monkeypox is caused by a virus similar to smallpox, which was declared eradicated in 1980. Infections are usually mild, with flu-like symptoms. A rash that spreads all over the body can develop, turning into blisters and scabs. Infected people usually recover in a few weeks. As with other poxviruses, the disease is more severe in young children and people with weaker immune systems. How dangerous it is depends on which of the two strains of the virus is involved. One, mostly found in past outbreaks in the Congo basin, is fatal about 10% of the time. The other, west African strain is less severe, with mortality estimated to be around 1%. These estimates are from outbreaks in remote places in Africa with poor health care. In rich countries monkeypox would probably be a lot less deadly.
A vaccine for monkeypox developed by Bavarian Nordic, a Danish biotechnology firm, was approved by American regulators in 2019. The vaccine is also approved for smallpox and data from Africa suggest that past smallpox vaccination is at least 85% effective in preventing monkeypox. America’s Centres for Disease Control and Prevention says the jab is most useful if given before or within four days of exposure to the virus. Even if it is given up to 14 days after exposure it may still help, by reducing symptoms. Evidence from animal studies suggests that some antiviral medicines used for other poxviruses may be useful too.
Also encouraging is that the monkeypox virus is not particularly good at spreading between people, and nowhere near as contagious as (for example) measles. It was first discovered in Denmark, in a laboratory monkey (hence the name), but is thought to be mostly harboured by small rodents in Africa. In that continent many cases are acquired from wild animals, when people hunt them, handle the raw meat or eat it. For the virus to spread from one person to another requires close contact. It spreads through droplets from coughs and sneezes that enter the nose, throat or eyes. It can also be picked up through contact with the skin, clothes or bedding of an infected person who is shedding the virus from pustules or scabs. Symptoms usually appear five to 21 days after infection.
The tricky part is diagnosis. A monkeypox rash looks a lot like chickenpox. Confirming it requires sending samples to a specialist laboratory equipped to handle highly dangerous pathogens. At the moment, Britain has only one rare-pathogens laboratory designated to run tests for monkeypox.
That said, containing outbreaks of monkeypox should be relatively easy. Isolating confirmed or suspected cases and tracing their potentially infected contacts can stop chains of transmission. The smallpox jab will probably be used for “ring” vaccination of the close contacts of infected people and health workers at high risk. Britain and Spain are looking to stock up on the vaccine already. Ring vaccination of close contacts was successful in curbing some of the recent Ebola outbreaks in Africa.
In the next few days and weeks more cases of monkeypox are sure to be found. But it is unlikely that the outbreaks will spread out of control. Covid-19 caught the world unprepared, with no drugs or vaccines at the ready. Monkeypox, however, is in an entirely different—and lesser—league.■