The first case of mpox in humans occurred in the Democratic Republic of the Congo (DRC) in 1970. Since the 1980s, there has been a slow rise in the number of cases in certain countries, primarily the DRC and Nigeria. This is probably linked to the end of routine smallpox vaccination in 1980.
A global outbreak of mpox (subtype II) began in 2022, which mainly spread through sexual contact. Since 2023, there has been a sharp increase in the number of cases of mpox (subtype I) in the DRC. The World Health Organization (WHO) declared the outbreak an international public health crisis on 14 August 2024. The DRC is particularly affected, but an increasing number of other African countries are also affected.
The risk of being infected in Norway is low.
How you get mpox
Infection from person to person usually occurs through close physical contact with rashes and bodily fluids. Sexual contact with an infected person increases the risk. You can also be infected via droplets, such as those caused by coughing and sneezing, but this requires close physical contact over a long period of time (hours).
The presence of the virus has been detected in semen long after a person has recovered, but it is uncertain whether this poses a risk of further infection. It is therefore recommended that you use a condom during intercourse for 12 weeks after you have recovered.
In African countries where the disease has its natural prevalence, the virus can also be passed from rodents to humans.
How long can you be infected before symptoms appear?
It normally takes between 6 and 13 days from infection until you become ill (incubation period), but this period varies and can be either shorter or longer (up to 21 days).
You can only pass on the infection to others while you have the symptoms. In other words, you cannot infect other people during the incubation period before you become ill.
What are the symptoms of mpox?
The most common symptoms of mpox are:
- rash and fever (above 38°C)
- swollen and painful lymph nodes
- sore throat
- headaches
- fatigue
- muscle pain
The rash develops into blisters, which scab and then dry up and fall off. Scarring may occur.
The rash normally starts on the part of the body that were exposed to infection. For many people affected by the outbreak in 2022, the rash started around the genitals and the rectal region. Many infected people only developed a few blisters.
The rash can also begin elsewhere on the body, such as the face, mouth or hands. Some people also develop rashes on their palms and the soles of their feet. In severe cases, the rash can also spread to the rest of the body. In those cases, the rash can resemble chickenpox.
Some people experience pain in and around the rash, including in the lymph nodes.
Children, pregnant women and people with weakened immune systems are at greater risk of becoming seriously ill from mpox.
The symptoms normally last 2 to 4 weeks. You are contagious from the onset of symptoms until the scabs have fallen off and new skin has formed underneath (around 3 weeks).
Testing, examination and treatment
If you have been exposed to infection, you should pay particular attention to the symptoms of the illness mentioned above.
If you suspect you may be infected with mpox, you should avoid close physical contact with other people and consult your doctor. The symptoms can be similar to many other common illnesses. It is therefore important that you are examined by a doctor, who will also consider whether you should take a test. You cannot take a test to find out whether or not you are infected until you become ill.
Most people do not need any treatment beyond symptom relief, such as antipyretic or pain-relieving medicine.
Cases of severe illness or hospitalisation are rare.
Examination, testing and treatment are free of charge.
Mpox vaccine
A vaccine is available for use against mpox. This vaccine can be administered either before or after infection. The vaccine is offered to people who are at greater risk of being infected with mpox.
The vaccine is sometimes offered to people who have been exposed to mpox infection. This is considered in each individual case. Being vaccinated after you have been exposed to the virus will not necessarily prevent you from becoming ill, but it may make the symptoms milder.
The vaccine will provide you with the best protection if it is administered within a few days after you have been infected, and will probably have little or no effect if it is administered after you have developed symptoms.
Travel
Travel to countries with mpox infection is not currently discouraged.
Anyone intending to travel or stay in a region with known mpox infection should:
- find out about the general situation at your destination and follow the advice issued by the local authorities
- avoid close physical contact with anyone who has been infected
- avoid having many/casual sexual partners
- avoid close physical contact with animals, both live and dead
- avoid eating meat that has not been cooked thoroughly and meat from wild animals (bushmeat)
As always, good hand hygiene is an important infection control measure.
More information about mpox can be found on the Norwegian Institute of Public Health’s website.