What is mpox?

Mpox is a viral infection that originally occurred mainly in West and Central Africa. It is a zoonosis: a disease that can be transmitted from animals to humans. In Africa, the virus is mainly transmitted to humans from rodents, rabbits and monkeys. People can also infect each other.

The mpox virus can be categorised into two main groups: Clade 1 and Clade 2. People usually do not become as seriously ill from the mpox viruses in Clade 2. Also, fewer people die from these infections compared to the mpox viruses in Clade 1. In 2022, there was a global outbreak of infections involving an mpox variant from Clade 2: mpox 2b. There was also an outbreak of mpox in the Netherlands, which mainly affected men who have sex with men.

Since 2023, there have been several outbreaks in Central Africa involving mpox viruses from Clade 1. In addition to the previously known mpox variant 1a, a new variant from Clade 1 was also found: mpox 1b. Much is still unclear about this new variant. For example, we do not know if this variant is more infectious.

How can I recognise mpox?

The main symptom of mpox is the skin rash. These pox can present as red spots, bumps or blisters. They can be painful. The blisters dry up and form a crust, leaving scabs that fall off 2 to 3 weeks later. They may cause permanent scars.

Other symptoms associated with mpox include:

• fever
• headache
• muscle ache
• swollen lymph nodes 
• chills
• tiredness

Some cases of mpox start with these symptoms followed by the skin rash, while others start with the rash and then develop other symptoms. The pox can also occur in the mouth and form ulcers.

During the 2022 outbreak, a number of patients also had proctitis, a painful inflammation of the lining of the rectum (the final part of the intestines). Sometimes proctitis is the only symptom.

How might I catch mpox?

Anyone can get mpox, and infections with the virus occur in all age categories. The virus is transmitted through close or intimate contact (cuddling, kissing, making love and sexual intercourse) with someone who is infected. Most of the infections in the Netherlands involving the Clade 2 mpox virus have involved MSM contact (men who have sex with men). The highest risk of infection is among men who frequently have sex with multiple male partners. However, mpox is not a sexually transmitted infection (STI), because sex is not the only way the virus can be transmitted.

The blisters and the scabs from the blisters can transmit the virus. The virus can enter the body through the mucous membranes or through tiny wounds or tears in the skin. Very occasionally, the virus is also transmitted through contact with contaminated materials (such as bedding or towels). The virus may also be able to spread via droplets from the mouth and nose while talking or breathing, if people are very close to each other. The risk of spreading mpox in this way currently appears to be minimal.

Some people develop flu-like symptoms or a skin rash before the pox appear. They may already be contagious at that point. The pox may also form in less visible locations, such as in the mouth (ulcers) or inside the rectum. Some people with mpox only have 1 blister.

Close-up of an mpox lesion

How can I prevent mpox?

You can reduce the risk of mpox by not having intimate or skin-to-skin contact with people who have mpox. In regions with mpox outbreaks, it is important to be alert and avoid intimate contact and direct skin contact. Less contact involving sex and cuddling lowers the risk of infection. By quickly recognising symptoms that could indicate mpox, you help prevent the virus from continuing to spread. If you or your partner may have been infected, it is important not to have sexual intercourse or any intimate contact – not even with a condom. If you or your partner has had mpox, the recommendation is to use a condom during sex for another 12 weeks after the scabs disappear.

What should I do if I have mpox?

If 1 or more of the following apply, call your GP or the Municipal Public Health Services (GGDs):

• You have 1 or more blisters or sores on your body, especially around the anus, penis or vagina or on the face, and you have had direct skin contact with someone who has mpox.
• You have 1 or more blisters or sores on your body, especially around the anus, penis or vagina or on the face, and you have been in a region of the African continent where mpox is currently prevalent (such as the Democratic Republic of Congo and the surrounding countries).
• You have had close contact or sexual contact in the past 3 weeks with someone who has mpox.

The GP or GGD may test you for mpox. If you test positive for mpox, the Municipal Public Health Service (GGD) starts source and contact tracing. The aim is to find out who gave you mpox and who in your surroundings may be at risk for getting mpox. Source and contact tracing differentiates between low, medium and high-risk contacts. High-risk contacts can be vaccinated in consultation with the GGD.

If you test positive for mpox, you need to self-isolate (stay at home) and follow the rules for isolation. You should not have any physical contact with others until all the symptoms are gone. In the context of mpox, that means that all the scabs from the blisters must have fallen off and new skin must have formed. This is because the scabs can also transmit the virus. It often takes 2 to 3 weeks for the scabs to go away. If you also have proctitis (inflammation of the lining of the rectum), all the symptoms associated with proctitis, such as anal discomfort, must also have resolved completely.

Is there any treatment for mpox?

In most cases, mpox goes away on its own within a few weeks. Sometimes a doctor recommends antiviral drugs.

How common is mpox in the Netherlands?

In 2022, a Clade 2 mpox virus was detected in people in Europe who had no direct connection to the affected areas in Africa where the disease has been circulating for some time. Mpox then spread throughout Europe, North America and other new areas. People in the Netherlands also contracted mpox. After a spike in the summer of 2022, the number of reported cases declined sharply in the fall of 2022. Cases are still occasionally being detected even now.

Since September 2023, outbreaks with a new virus variant within Clade 1, mpox 1b, have been occurring in the Democratic Republic of Congo (DRC) and surrounding countries. RIVM is closely monitoring the reported cases of mpox and posting updates on the current situation on the website.