Seven months after the World Health Organization downgraded mpox from a global threat, an outbreak in Africa could go beyond the continent's borders. What is mpox and how dangerous is it? After a year in which nearly 90,000 people were infected with mpox, and 140 people died, the World Health Organization downgraded the disease in May 2023 from its status as a global health emergency. Mpox, formerly known as monkeypox, had spread rapidly in the third year of the COVID-19 pandemic when awareness of public health was at a maximum.

"Mpox continues to pose significant public health challenges that need a robust, proactive and sustainable response," said WHO chief, Tedros Adhanom Ghebreyesus, at the time. And he was right. By mid-December, the WHO was sounding the mpox alarm again.

What is the current mpox threat?

On December 15, the WHO warned that an epidemic of mpox in the Democratic Republic of Congo (DRC) could spread internationally, as a rise in sexual transmissions had been detected. Japan's health ministry reported two days earlier (December 13) that the country had seen its first fatality from mpox. The patient had a prior infection with HIV and no travel history, said the health ministry in a statement, and it was not immediately clear how they had become infected.

There are ongoing outbreaks in Asia — in Japan, Cambodia, Indonesia, Vietnam and China — so, the case needn't have come from Africa. But Rosamund Lewis, the WHO's technical lead for mpox, said the organization was "concerned" about further international transmission from the DRC. There was a "rapidly expanding outbreak in the country," she explained, with more than 13,000 suspected cases of the disease — more than 1,000 per month — and up to or more than 600 deaths so far.

How do you get mpox?

While mpox can be transmitted sexually, experts do not describe the disease as a sexually transmitted infection (STI). But sex is one of the main transmission routes. The WHO's official advice states that mpox is spread by close contact with an infected person. That includes talking and breathing near an infected person — via "droplets” as we learned during the COVID pandemic, but also via sexual activity:

"[S]kin-to-skin (touching or vaginal/anal sex); mouth-to-mouth (such as kissing); or mouth-to-skin contact (such as oral sex or kissing the skin). During the global outbreak that began in 2022, the virus mostly spread through sexual contact." [our emphasis]It can also spread via cuts, lesions and contact with mucous membranes — washing hands after any such contact, and disinfecting surfaces, is essential for preventing mpox to spread.

Mpox can also be transmitted from animals to humans, for instance if an infected animal is consumed by a human but the meat is not sufficiently cooked. There are indications that mpox can also spread from humans to animals, such as pets, but the evidence is inconclusive.

What exactly is mpox?

Mpox is an infectious virus called monkeypox. Experts now prefer to call it mpox to avoid associations with monkeys or the idea that it does not affect people. It was first discovered in 1958 among monkeys used for research in a Danish laboratory. The first reported human case of the disease was in a nine-month-old boy in the Democratic Republic of the Congo in 1970.

What are the symptoms of mpox?

A common symptom of mpox is a rash that persists for 2-4 weeks. An mpox rash — often a blister or soar — can affect the face, palms of the hands and soles of the feet, and groin, genital and anal regions of the body. The extent of the rash can range from just a few blisters to thousands, with lesions found in the mouth, throat, rectum and vagina — hence, that heightened risk of transmission through sexual activity.

Further symptoms are typical of other viral infections: fever, headache, muscle pain, low energy, and swollen glands. In severe cases, mpox has been linked to secondary bacterial infections, and can spread to the lungs, eyes, brain and heart. The mpox mortality rate lies between 0.1% and 10% of cases.

How is mpox treated?

There is an antiviral medication called tecovirimat SIGA, which is used to treat monkeypox, cowpox and smallpox — the latter is an eradicated disease. The European Medicines Agency — Europe's drug approval body — says the three infections are all caused by viruses that belong to the same family, known as orthopoxviruses. Tecovirimat interferes with a protein (called VP37) found on the surface of the virus and slows down its ability to spread.

Are there any mpox vaccines?

There are three vaccines against mpox — derived through research into smallpox. Currently, the WHO does not advise mass vaccination against mpox. It says "only people who are at risk should be considered for vaccination” and people at risk are those who have close contact with an infected person — including, but not limited to, sexual partners and healthcare workers.