Mpox is a viral disease caused by the Mpox virus (MPXV) from the genus Orthopoxvirus, which also includes the human smallpox viruses. The disease is similar to smallpox in humans, but is generally milder. The severity of the disease varies depending on the clade (virus variant). The former name "monkeypox" or "monkeypox" is a misnomer. The name was coined in 1958 when a Danish laboratory first discovered the virus in Asian monkeys. In November 2022, the WHO changed the name of the disease to Mpox.

Mpox is endemic in many countries in Central and West Africa, where it circulates in animal populations, especially small mammals.

The natural hosts of the Mpox virus (MPXV) are mainly small, forest-dwelling rodents, such as African chipmunks, dormice or Gambian giant hamster rats.

Mpox can be transmitted through physical contact with an infected person, with contaminated material (e.g. clothing, bed linen) or with infected animals. Transmission occurs through secretions and droplets as well as contact with skin lesions or crusts of infected persons, or contact with objects that have been in contact with the infected person, for example when sleeping in the same bed as an infected person. Clade 2 of MPXV is mainly transmitted through sexual contact. Normally, Mpox cases in Europe were associated with travelling activities or, in individual cases, were transmitted by imported animals. With the international Mpox outbreak in 2022, human-to-human transmissions were detected more frequently in Europe. As a result, the disease has been under increased scrutiny since then.

High fever, severe headache, sore throat, cough, malaise, occasionally diarrhoea. A smallpox-like exanthema (skin rash) may occur in the second stage of the disease. The disease is usually mild to moderate in adults and is self-limiting. Complicated courses with the formation of painful ulcers and death of skin areas as well as abscess formation due to secondary bacterial infections can occur.

The symptoms are treated. The drug Tecovirimat has been authorised for the treatment of smallpox, mpox and cowpox in the EU since January 2022. Due to the rarity of the diseases, the authorisation is granted under "exceptional circumstances".

You can protect yourself from Mpox by avoiding contact with infected persons or objects used by them. Frequent anonymous sexual contact increases the risk. "Safer sex" rules are not sufficient for Mpox, as the virus can already be transmitted through skin contact. A person diagnosed with Mpox should isolate themselves and avoid contact with other people until the rash has completely healed.

Two vaccines against Mpox have been available in Austria since 2022, including as post-exposure prophylaxis (PEP), i.e. after physical contact with a person suffering from Mpox.

Since 23 May 2022, 359 cases of Mpox have been reported in Austria (as of 20.11.2024). Of these, eleven cases of Mpox were reported in 2023 and 21 cases so far in 2024. The disease is notifiable.

Ministry of Health: Case definition, recommendation for the official procedure in the event of contact with Mpox (monkeypox)

A joint ECDC/WHO Regional Office for Europe report provides an overview of the total number of Mpox cases detected by the ECDC and the WHO Regional Office for Europe.

The World Health Organisation (WHO) calls on healthcare facilities to consider Mpox as a differential diagnosis when symptoms are present. If the suspicion of Mpox is confirmed, patients should be isolated and contacts traced. Anyone who has symptoms themselves should be examined by infectious disease specialists, especially men who have sex with men with changing partners should be vigilant.

Information from the WHO on Mpox

The following virus variants, or clades, of MPXV are currently circulating, which differ in the severity of the symptoms:

Clade 1a and 1b: These virus variants of clade 1 probably cause more severe courses of disease with a higher mortality rate than those of clade 2. The new clade 1b was discovered in 2023 in the east of the Democratic Republic of Congo. According to the WHO, clade 1b shows a further adaptation of the virus to humans(RKI, as of 16 August 2024). The variant formerly known as the "Congo Basin or Central Africa clade" was first detected in the Democratic Republic of the Congo. Since 2023, clade 1b has continued to spread in the DRC and from there to many other African countries that previously had no cases of this clade. This rapid spread poses a significant challenge for the affected regions. Due to a sharp increase in Mpox cases in several African countries in 2024, triggered by clade 1b, the WHO once again declared a public health emergency of international concern for Mpox on 14 August 2024.

Clade 2: This virus variant generally causes milder courses of the disease with a lower mortality rate. It is less contagious and the symptoms, especially the skin lesions, are less pronounced. The infection is usually cured after around three weeks. The clade formerly known as the "West African strain" is mainly found in West Africa, particularly in Nigeria, Cameroon, Liberia and Sierra Leone. In 2022, clade 2 spread internationally, prompting the WHO to declare a "public health emergency of international concern (PHEIC)". After the outbreak was brought under control, this alert level was lifted again in May 2023.

Subclades Ia and Ib were defined based on the occurrence of subclade Ib in the Democratic Republic of the Congo. It is currently assumed that subclade Ia includes all other strains of clade I that are not Ib.

The ECDC categorises the general risk of Mpox infection for the European population as low. The likelihood of infection in people with multiple sexual partners in the EU/EEA who were not previously infected with MPXV clade 2 or were not fully vaccinated during the outbreak in 2022 is classified as moderate.

The likelihood of infection with MPXV clade 1 in close contact with possible or confirmed imported cases is high, but the severity of the disease is likely to be low. (as of 15/08/2024)

All EU countries are called upon to identify and isolate cases as quickly as possible and to trace close contacts. To this end, diagnostic capacities should be created and a functioning system for contact tracing established. Healthcare and laboratory staff should wear appropriate protective equipment (gloves, FFP2 mask, waterproof overgarments) if Mpox is suspected

The WHO calls on healthcare facilities to consider Mpox as a differential diagnosis in the event of corresponding symptoms. If the suspicion of Mpox is confirmed, patients should be isolated and contacts traced. Men who have sex with men with changing partners should be particularly vigilant.

The vaccine approved in the EU against smallpox (Imvanex ®) was also approved against Mpox on 22 July 2022. In Austria, Imvanex and the US vaccine Jynneos are available in limited quantities with a licence from the US authority (FDA) against Mpox - see "Mpox vaccination recommendation".

Both Jynneos and Imvanex are a vaccine manufactured by Bavarian Nordic, which is a 3rd generation live attenuated vaccine (MVA-BN) based on the modified vaccinia virus Ankara and is authorised in both the EU (Imvanex) and the US (Jynneos) as a vaccine against Mpox in addition to its use against smallpox. These two vaccines are comparable, with only minor differences in the manufacturing process. Both vaccines are administered in two doses, 28 days apart. One dose is sufficient for people who received a smallpox vaccination as a child.

Imvanex product informationand instructions for use (see product information: product information pages 2-13, instructions for use pages 24-29)

The English-language US technical information is available for users here.

Should side effects occur during or after use of the vaccine, these can and should be reported to the Austrian Medicines Agency (BASG), as with any other medicinal product.

Mpox is a notifiable animal disease under the Animal Diseases Act.

The mpox virus is endemic to West and Central Africa. Here it circulates mainly in small mammals. Rodents in particular are the reservoir of the pathogen for primates and humans. Primates and humans are actually false hosts.

Mpox has been detected in many rodents in Africa: in rats such as the hamster rats popular as pets, the Gambian giant hamster rat(Cricetomys gambianus), in other Cricetomys species, in red-nosed rats(Oenomys hypoxanthus) and proboscis rats (Petrodromus sp.) as well as in striped grass mice(Lemniscomys sp.), in dormice (dormice, African Lorrain's milk Graphiurus lorraineus), in squirrels (e.g., in African chipmunks Funisciurus sp. and sun squirrels(Heliosciurus sp.), and in shrews. The exact host range is not yet known. Many of these rodent species, which are also readily exported to other continents as zoo or pet animals, can - if infected with the pathogen - transmit it to other animal species but also to humans (e.g., in 2003 in the USA to prairie dogs and humans).

Transmission of infection from pets and zoo animals to humans can occur through direct contact (bites, secretions, respiratory droplets, skin-to-skin contact with smallpox lesions). Contact via the environment, e.g., through virus-containing shed skin crusts during cage cleaning, is also possible. Particularly high concentrations of pathogens are found in typical smallpox lesions. Smallpox viruses can persist in the environment for a very long time in the shed skin crusts. Conversely, people suffering from mpox should avoid any contact with their pets (especially rodents) in order to protect the animals.

To date, no endemic occurrence of mpox in animals - especially rodents - has been detected in either the Americas or Europe. In any case, pets and zoo animals imported from Africa should be examined by a veterinarian for the skin lesions typical of smallpox and kept in quarantine for a short time before being brought together with other animals. Specialized personnel in zoos and pet shops should be aware of the risk of mpox infection upon first contact with these animals imported from Africa and implement protective and hygienic measures accordingly: These include wearing disposable gloves, disposable masks, disposable work coats, hand disinfection, avoiding stirring up dust when cleaning cages, proper disposal of bedding material.

World Organisation for Animal Health (WOAH): Mypox

Information from EFSA on mpox