Here’s what Dr Mike Skinner, reader in virology at Imperial College London, and Martin Michaelis, professor of molecular medicine at the University of Kent, had to say.
1. What is monkeypox?
Prof Michaelis: Monkeypox is an infectious disease, which is caused by the monkeypox virus. The monkeypox virus is closely related to the smallpox virus but less contagious and less deadly. It is not related to the Varicella zoster virus that causes chickenpox.
Dr Skinner: Monkeypox is a large and complex virus. It is closely related to the smallpox virus, which was eradicated in 1980 by vaccination with the vaccinia virus – which also protects against monkeypox.
Monkeypox was first seen in monkeys in a medical facility in Copenhagen in 1958, with the first human cases seen in 1970.
2. How is it spread and how do you catch it?
Prof Michaelis: Monkeypox virus is endemic in parts of central and west Africa. Rodents are thought to be the main reservoir species, such as Gambian pouched rats, dormice, and African squirrels. Most human infections are caused by direct contact with infected animals.
You are unlikely to become infected when you are in the same room with an infected person, if there is no direct contact.
Dr Skinner: It is spread by close, even intimate, contact, for example when caring for children, bed-sharing or during sexual contact.
It can be caught and spread through broken skin or via the mouth or eyes after contact with pus from open spots (directly or from surfaces), by inhaling dust from dried scabs after they are shed into bedding and clothing, and by spread inhalation of droplets From the mouth or nose – but only over very short distances, unlike Covid.
3. Does it come from animals?
Dr Skinner: Yes, though not from monkeys but from small mammals – such as rodents, dormice, squirrels – in Africa.
Prof Michaelis: The main reservoir are rodents such as Gambian pouched rats, dormice, and African squirrels in central and west Africa. These rodents can then infect other animals and humans. Despite the name monkeypox, the monkeypox virus is not typically found in monkeys. The virus only received its name, because it was discovered in a cynomolgus monkey in 1958.
4. What are the symptoms of monkeypox?
Dr Skinner: A few days after infection, the first signs can be fever, headache, malaise, muscle pain, which precede appearance of a rash – the spots follow a course that passes through blisters – initially closed but later open – through to scabs which eventually fall off .
Prof Michaelis: Monkeypox patients have been described to be unwell for up to four weeks.
5. Is it deadly?
Dr Skinner: Only rarely, and it depends on the strain. The Central African (Congo) strain has a mortality rate in Africa of up to 10%. The West African (Nigerian) is milder, with a strain mortality rate in Africa of 1 to 2%.
No deaths were observed in the 2003 US outbreak of the West African strain, which passed to native prairie dog pets from imported African animals, despite 73 cases.
Prof Michaelis: As far as we know, the current British cases have been caused by monkeypox viruses from the least deadly West African strain.
The death rates have been determined in African countries with limited health care capacities. It is not clear how deadly monkeypox is in a high-income country like the UK with a developed health care system and modern intensive care facilities.
6. What is the treatment?
Dr Skinner: Normally supportive (fluids) but a modern version of the smallpox vaccine has been licensed for post-exposure as well as pre-exposure use. Antivirals are also available for post-exposure therapy.
Prof Michaelis: Smallpox vaccines provide a reasonable level of protection (about 85%) from monkeypox. Even if a smallpox vaccine is administered up to four days after infection, it is still expected to prevent disease. If the smallpox vaccine is administered later than this but before the onset of symptoms, it is still anticipated to reduce disease severity.
There is also an antiviral drug called tekovirimat that is approved for the treatment of smallpox in the US and that is expected to be also effective against monkeypox. Other antiviral drugs that have been shown to inhibit monkeypox in animal models include cidofovir and brincidofovir. However, clinical studies will be needed to find out how effective these drugs actually are against monkeypox in humans.
7. How can you avoid getting it?
Dr Skinner: Medical staff will use PPE. The vast majority of us will not come into close contact with infected individuals.
Prof Michaelis: Monkeypox is not as contagious as airborne diseases like the measles or Covid-19.
Close body contact or contact with body fluids or the lesions is normally required to become infected.
Transmission via aerosols has not been described, but people may become infected by larger droplets if a monkeypox patient directly coughs or sneezes at them.
Contact with clothes or bedding of monkeypox patients can result in the transmission of the disease.
Generally, the risk of infection via contaminated surfaces, for example doorknobs, seems to be higher for monkeypox than, for example, for Covid-19. Hence, thorough hygiene measures and hand washing as well as avoiding close contact with potential monkeypox patients should normally be sufficient to prevent infection.
8. Is it worse in children?
Dr Skinner: Experience in Africa suggests it can be more severe in children. It also poses increased risk to those who are immunosuppressed.
Prof Michaelis: Yes, children and pregnant women are at a higher risk from monkeypox than adults.
9. How did the current outbreak start and spread?
Dr Skinner: We have had sporadic, international, travel-related cases since an apparent increase in numbers in West Africa in 2017.
The first cases this year seem to be similar, but the latest cases, here and abroad, are in clusters – a couple linked epidemiologically in the UK – with no travel history to West Africa.
They seem to be linked in having extensive, close and intimate network contacts, in this case by being members of the men who have sex with men community.
Public health officials are looking for links between the clusters, nationally and internationally, as well as for earlier and hopefully index cases, although it is assumed their origin is West Africa, they may represent multiple introductions.
Prof Michaelis: This is not entirely clear. The monkeypox strain that causes the current outbreak is derived from West Africa, and it seems that all cases are linked back to a single case. It is not clear how the virus then spread around the world.
10. How can an outbreak be stopped?
Dr Skinner: Contact tracing by public health authorities after prompt recognition, isolation and confirmation of possible and probable cases, vigilance of those who are possible contacts and by willingness of cases to contact authorities if symptoms arise.