On Wednesday, the World Health Organization (WHO) declared that an acceleration in mpox infections in parts of Africa constitutes a public health emergency of international concern. Here’s what you need to know about the disease, where it’s spreading, and why health officials are so concerned.

What is mpox?

Mpox is the name given to the disease that results when people become infected with the Monkeypox virus, according to the Centers For Disease Control and Prevention (CDC). Mpox is a pox disease, which produces rashes and other skin irritations on the body. It is in the same family as the virus that causes smallpox.

According to the WHO, the virus that causes mpox was first discovered in research monkeys in Denmark in the late 1950s. In 1970, the first human case of mpox, then called Monkeypox, was detected in a child from the Democratic Republic of the Congo.

Mpox is a zoonotic disease, which means it can cross from animals to humans. There are two different groups of mpox viruses, known as clade I and clade II. Clade I is mainly found in Central African countries and it is the more deadly of the two, historically killing up to 10% of those infected. Clade II is more commonly found in West Africa and is much less fatal. The CDC says 99.9% of those infected with Clade II survive.

Why did the WHO declare a public health emergency?

The WHO’s declaration is officially known as a public health emergency of international concern (PHEIC). A PHEIC is defined by WHO as “an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response.”

The reason behind the declaration stems from the Africa Centres for Disease Control and Prevention (Africa CDC), which released data showing an alarming jump in the number of mpox cases and deaths in 2024 compared to the year earlier. Africa CDC says in 2024, mpox cases have surged by 160% and deaths have increased by 19%.

In announcing the PHEIC, WHO Director-General Dr. Tedros Adhanom Ghebreyesus said, ”The emergence of a new clade of mpox, its rapid spread in eastern DRC, and the reporting of cases in several neighbouring countries are very worrying. On top of outbreaks of other mpox clades in DRC and other countries in Africa, it’s clear that a coordinated international response is needed to stop these outbreaks and save lives.”

The WHO has previously issued PHEICs in recent years for other outbreaks, including swine flu in 2009, ebola in 2013, COVID-19 in 2020, and an earlier outbreak of mpox in 2022.

Where is the current outbreak of mpox?

Right now, the current mpox outbreak that constitutes the PHEIC is located in several African nations.

According to Africa CDC, clade I mpox is currently in the Central African Republic (CAR), the Republic of the Congo (Congo), the Democratic Republic of the Congo (DRC), and Rwanda. 

The clade II version of mpox is currently in Benin, Ghana, Liberia, Mozambique, Nigeria, and South Africa.

Finally, clade I and clade II are both in transmission in Cameroon. 

You can find a map of the mpox situation in Africa here, which is dated July 30.

How is mpox transmitted?

As a zoonotic disease, mpox can be transmitted from animals to humans. However, human-to-human transmission is also one of the main ways that the disease spreads. The WHO says transmission can occur from person to person, including via contact that is:

• face-to-face (talking or breathing)
• skin-to-skin (touching or vaginal/anal sex)
• mouth-to-mouth (kissing)
• mouth-to-skin contact (oral sex or kissing the skin)
• respiratory droplets or short-range aerosols from prolonged close contact

Animal-to-human transmission can occur through bites or scratches, or by handling or eating the infected animals. 

What are the symptoms of mpox?

The WHO says that symptoms usually begin about a week after infection, but can show up at any time between one and 21 days after exposure. Common symptoms of mpox infection are:

• rash
• fever
• sore throat
• headache
• muscle aches
• back pain
• low energy
• swollen lymph nodes

Symptoms generally last from two to four weeks, but can remain longer for those with weakened immune systems.

Is there an Mpox vacine?

Yes. It is called JYNNEOS. The CDC recommends people get the vaccine under several conditions, including if they have had exposure or suspect they may have had exposure to someone with mpox or if a person is at an occupational risk of contracting mpox.

Full recommendations for mpox vaccination can be found on the CDC’s website here.