A monkeypox virus particle captured via a coloured transmission electron micrograph
UK HEALTH SECURITY AGENCY / SCIENCE PHOTO LIBRARY
What is monkeypox?
Monkeypox is caused by a virus that is a relative of smallpox. As the name suggests, it was first identified in monkeys, and is mainly confined to West and Central Africa.
Why is it in the news?
On 7 May, the UK Health Security Agency (UKHSA) announced that someone had contracted monkeypox after recently travelling to Nigeria. The individual developed a rash on 29 April and returned to the UK on 4 May, when they were hospitalised. Two days later, a laboratory test confirmed that the individual had the monkeypox virus.
One week later, the UKHSA announced that two other people, not related to the case announced on 7 May, had been diagnosed with the monkeypox virus. These individuals live together, with one requiring hospital care and the other isolating.
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As of 3 August, nearly 25,000 confirmed or suspected monkeypox cases have been reported worldwide since the outbreak emerged, according to a list of reports being compiled by Moritz Kraemer at the University of Oxford, John Brownstein at Boston Children’s Hospital and their colleagues.
What are the symptoms?
Monkeypox is usually mild, with most people recovering without treatment within a few weeks.
Symptoms usually appear five to 21 days post-infection.
Official bodies like the NHS, US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recognise a wide range of potential symptoms. These can include fever, headache, muscle aches, backache, swollen lymph nodes, chills, exhaustion and joint pain. Respiratory symptoms – such as coughing, a blocked nose and sore throat – can also occur. The headache and exhaustion can be particularly intense.
Most people with monkeypox develop a chickenpox-like rash that appears one to five days after any initial symptoms, often beginning on the face. The rash may then spread, commonly to the palms, soles of the feet, mouth and genitals. It can also affect the conjunctivae, the membrane that covers part of the front surface of the eye and the inner surface of the eyelids.
An anal rash, pain and bleeding are also potential symptoms.
The rash goes through several stages, starting as raised spots and developing into papules and fluid-filled pustules, before eventually forming a scab that falls off.
Monkeypox symptoms can vary substantially from person to person. For example, some only develop a rash, while others have all of the above signs of infection. The number of skin lesions can also vary from a few to several thousand.
How serious is the disease?
Monkeypox is usually mild, with most people recovering within a few weeks without treatment.
There are two main types of monkeypox: the Congo strain and the West African strain. The WHO states monkeypox has a reported death rate of between 1 per cent and 10 per cent, however, that applies to the Congo strain, while the West African strain is deadly in around 1 in 100 reported cases.
Amid the ongoing outbreak, virus sequencing information is limited. However, only the West African strain has been identified so far.
The reported death rates also only refer to the proportion of deaths in people who are confirmed to be infected, called the case fatality ratio. But with diseases whose symptoms can be mild, many cases go undetected, meaning the infection fatality ratio – the proportion of deaths among all those infected – can be substantially lower.
According to the WHO, children with monkeypox are more likely than adults to become seriously ill. Becoming infected during pregnancy can also lead to complications, including stillbirth.
How does monkeypox spread?
Monkeypox can be caught from infected wild animals in parts of West and Central Africa. This may occur if you are bitten or if you touch the animal’s blood, fluids, spots, blisters or scabs. Monkeypox may also be transmitted by eating the undercooked meat of an infected animal.
The virus doesn’t pass very easily between people. However, transmission can occur via contact with bodily fluids, blisters or scabs, or getting close enough to breathe in large airborne droplets. These droplets generally can’t travel more than 1 metre or so, according to the CDC. Touching clothing, bedding or towels used by someone with monkeypox may also be a risk.
Is there a vaccine? And how is monkeypox treated?
A vaccine called Jynneos (also known as Imvanex and Imvamune) is approved in the US and Europe for preventing monkeypox and smallpox in people over 18. In the UK, people who are particularly at risk are being offered a vaccine, including some healthcare workers and men who have sex with men.
People who are old enough to have been vaccinated against smallpox as babies should also have some protection against monkeypox. Routine smallpox vaccination ended in the UK in 1971 and in the US in 1972.
When it comes to treatments, the antiviral drug tecovirimat (also sold under its brand name Tpoxx) is approved in Europe for monkeypox, smallpox and cowpox. It is only approved for smallpox in the US.
So why the fuss?
Any disease that circulates in animals and can be passed to people has potential to cause a new pandemic, if it mutates to become more deadly or more easily transmissible.
Monkeypox is considerably less transmissible than other infections, like covid-19, and already has vaccine and treatment options.
Nevertheless, the WHO declared monkeypox a global health emergency – its highest alert level – on 23 July, putting the outbreak on par with covid-19.
The panel was split on whether to declare monkeypox a global emergency, with director-general Tedros Adhanom Ghebreyesus acting as a tiebreaker. Some members of the panel argued the disease isn’t so severe and case numbers don’t seem to be rising exponentially, while others countered that confirmed case numbers are probably an underestimate and the disease requires a coordinated international response.
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