Mpox

Mpox (previously known as monkeypox) is an infectious disease caused by an orthopoxvirus.

It is a zoonotic disease, i.e., a disease that can spread from animals to people. It is normally transmitted to humans by wild rodents or primates in the forest areas of Central and Western Africa, but it can also spread among humans.

After an incubation period of between 5 and 21 days, the disease often starts with a fever, muscular pain, fatigue and swollen lymph nodes (under the jaw, on the neck or in the groin area, etc.).

Skin eruptions (pustules and small pus-filled blisters) appear after one to three days, often on the part of the body where the virus first enters the body (peri-anal region, penis, mouth, face and other parts of the body). Sometimes, the skin eruptions are not very pronounced and can go unnoticed. Unlike chickenpox, the skin eruptions occur all at once. The lesions go through several stages (macules, papules, pustules and then scabs) and evolve simultaneously. Infection mainly occurs through direct contact with pustules or lesions, which contain a high concentration of the virus. When the scabs fall off, sufferers are generally no longer contagious, except through sexual contact.

The disease often clears up on its own after 2 or 3 weeks.

Since spring 2022, a variant of the Mpox virus – known as the clade IIb strain – has been behind an epidemic outside of Africa, affecting Europe (including Luxembourg) and all regions of the world. The vast majority of cases have been detected in men who have sex with men. The virus primarily spreads from person to person during sexual and/or intimate contact with an infected person. Having several sexual partners in the space of a few weeks encourages transmission.

Since 2022, over 22,000 mpox cases have been reported in Europe (EU/EEA), including 685 cases in 2024. In Luxembourg, 57 cases of mpox were reported in 2022, three in 2023, and just one in 2024. Currently, the cases reported in Europe and Luxembourg tend to be benign and have a very low associated mortality rate (0.05 %). There have been no deaths attributable to mpox infection in Luxembourg.

The clade IIb variant is still spreading in Europe, but the number of cases is low. What is known about the current monkeypox epidemic in several countries around the world? What is the situation in Luxembourg?

Information on the number of cases of mpox detected worldwide and in Luxembourg can be found here:

Joint ECDC-WHO Regional Office for Europe Monkeypox Surveillance Bulletin (europa.eu)

In 2024, the Democratic Republic of Congo (DRC) reported an outbreak of mpox, with 16,789 cases, including 2,638 confirmed and 511 deaths. This epidemic represents the largest number of clade I cases ever seen in Africa. Historically, clade I mpox infections have been considered more serious than clade II infections, due to their higher mortality rates. Several modes of transmission, including direct inter-personal contact and sexual transmission, have been identified, particularly in the east of the country where the clade Ib variant is spreading. Most of the cases in the DRC are among children under the age of 15, who account for 66 % of infections and 82 % of deaths. There is also a preponderance of cases in males (73 %). The situation in the DRC has regional repercussions, with confirmed cases in five of the eight neighbouring countries, including Burundi, Congo and the Central African Republic.

In response to this health crisis, Africa CDC (Africa Centres for Disease Control and Prevention) and the WHO declared public health or security emergencies in August 2024. These declarations seek to mobilise resources, improve communication about the risks, step up monitoring and testing capabilities, and reinforce the human resources to fight this epidemic.

In its risk assessment, the European Centre for Disease Prevention and Control (ECDC) estimated that there is a high probability of clade I mpox cases being imported into Europe, but the risk of infection and transmission for the general public is low or very low.

In August 2022, Luxembourg's National Infectious Diseases Service (Service national des maladies infectieuses) at the Centre hospitalier de Luxembourg began a targeted vaccination campaign in partnership with the Health Directorate.

The preventive vaccination campaign was aimed mainly at men who have sexual relations with men and who report having multiple sexual partners, transsexual people who report having multiple sexual partners, and sex workers (https://sante.public.lu/dam-assets/fr/espace-professionnel/recommandations/conseil-maladies-infectieuses/variole-singe/2022-07-28-csmi-mpx-vaccination.pdf). People who have been fully vaccinated with the Jynneos or Imvanex vaccines are considered to be protected against the new variant.

Since 2022, more than 800 first doses and 600 second doses have been administered. An increasing number of studies have demonstrated the effectiveness of vaccination, and substantiate the fact that vaccination helped to contain the mpox epidemic in 2022. 

The disease is self-limiting, and most people recover within a few weeks.

Treatment is, above all, symptomatic and supportive, as it is important to ease pain and treat secondary infections, where necessary.

The virus is detected by polymerase chain reaction (PCR) testing of skin lesions, vesicular fluid, the contents of pustules, scabs, or skin and other samples taken during the acute phase of the disease.

People over 50 years of age, who have no doubt been vaccinated against chickenpox, have some protection against mpox infection. Nonetheless, protection is not absolute and they should continue to take precautions to protect themselves and others.

Newborns, children, pregnant women, the elderly and people suffering with underlying immune deficiencies can be seriously affected by mpox. Healthcare personnel are also more exposed to the risk of mpox infection, owing to direct and frequent contact with infected people, but hand hygiene and wearing gloves provide effective protection.

Serious complications of mpox include secondary skin infections, pneumonia, confusion, eye infections that can lead to loss of sight, and encephalitis. According to the WHO, around 3 to 6 % of cases reported in Central or West Africa in recent years resulted in death, often in children (where mortality can reach 11 %) or people suffering from other health problems. It is important to note that this may be an overestimation, as monitoring is very limited in endemic countries.

The mpox virus can be transmitted between individuals through close physical contact, including sexual contact. It is not currently known for sure whether mpox can be spread via sperm or vaginal secretions, but direct contact with skin lesions during sexual activity can result in contamination. We also know that sperm can contain a high viral load, and that the virus can replicate in sperm, so it is potentially infecting.

Mpox eruptions often appear on the genitals, around the anus and in the mouth, which most likely contributes to transmission during sexual contact. The mpox virus can also be spread by mouth-to-mouth contact if skin or oral lesions are present.

The risk of contracting the mpox virus is not limited to people who have sexual contact. Anyone who has close physical contact with a contagious person can be infected. Anyone with symptoms that suggest mpox infection and who has had high-risk contact should therefore avoid close physical contact with others, and seek the advice of a healthcare professional immediately.

In its risk assessment published on 16 August 2024, the European ECDC agency declared that there was a high risk of clade I mpox cases being imported from Africa into Europe, but that the risk of infection for the general public in Europe was currently low. Therefore, there is currently no risk of a major epidemic in Luxembourg.

https://www.ecdc.europa.eu/en/publications-data/risk-assessment-mpox-epidemic-monkeypox-virus-clade-i-africa