Mpox

Monkeypox is a rare zoonotic disease first discovered in monkeys and in humans in 1970 in the Democratic Republic of Congo. It mostly occurs in Central and Western African countries often close to tropical rainforests. However, it can be exported as happened in recent years in the United States, the United Kingdom, Israel and Singapore.

Monkeypox is a serious disease. Studies of monkeypox in Central Africa, where many people live in remote areas and are medically underserved, showed that the disease killed 1—10 per cent of people infected.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community surveillance, volunteers should use broad (simplified) case definitions to recognize most or all possible cases and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Clinical criteria: particular rash, fever (subjective or measured temperature of over 99.3° F [over 37.4° C]), other clinical signs and symptoms (chills and/or sweats, headache, backache, lymphadenopathy, sore throat, cough, shortness of breath).

Epidemiologic criteria: exposure to an exotic or wild mammalian pet with clinical signs of illness (e.g. conjunctivitis, respiratory symptoms, and/or rash) OR exposure to an exotic or wild mammalian pet with or without clinical signs of illness that has been in contact with either a mammalian pet or a human with monkeypox OR exposure to a suspect, probable, or confirmed human case of monkeypox.

Laboratory criteria: isolation of monkeypox virus in culture OR demonstration of monkeypox virus DNA by polymerase chain reaction (PCR) testing of a clinical specimen OR demonstration of virus morphologically consistent with an orthopoxvirus by electron microscopy in the absence of exposure to another orthopoxvirus OR demonstration of presence of orthopoxvirus in tissue using immunohistochemical testing methods in the absence of exposure to another orthopoxvirus.

Case classification

Suspect case: meets one of the epidemiologic criteria AND fever or unexplained rash AND two or more other signs or symptoms with onset of first sign or symptom less than 21 days after last exposure meeting epidemiologic criteria.

Probable case: meets one of the epidemiologic criteria AND fever AND vesicular-pustular rash with onset of first sign or symptom less than 21 days after last exposure meeting epidemiologic criteria OR if rash is present but the type is not described, demonstrates elevated levels of IgM antibodies reactive with orthopoxvirus between at least days 7 to 56 after rash onset.

Confirmed case: meets one of the laboratory criteria.

WHO case definition source of information: https://www.who.int/emergencies/outbreak-toolkit/disease-outbreak-toolboxes/monkeypox-outbreak-toolbox

• People in close contact with infected animals (including the animal’s blood and other bodily fluids).
• Eating inadequately cooked meat of infected animals.
• No proper sanitation and hygiene measures.
• Caregivers and healthcare workers in close contact with infected people when infection control precautions are not strictly practised.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

3—28 per cent in recent outbreaks among close contacts.

• Infection is more severe and mortality is higher among children and young adults.
• Immunosuppressed persons such as those receiving chemotherapy,  transplant recipients or HIV carriers.
• People with chronic diseases such as renal disease, cancer, chronic lung or liver disease and diabetes.

Monkeypox virus.

Zoonotic disease: The natural reservoir of monkeypox viruses is not identified. Hosts include many animals such as rope squirrels, tree squirrels, Gambian rats, striped mice, dormice, prairie dogs and primates.

• Contact transmission: Primarily transmitted to people through direct contact with the blood, body fluids, or cutaneous or mucosal lesions of infected animals (monkey, prairie dogs, rats, squirrels, and others), during bite or scratch. Human-to-human transmission is limited but can happen by contact with body fluids, skin lesions or contaminated objects (e.g. bedding) of an infected person.
• Vehicle-borne transmission: Eating inadequately cooked meat of infected animals is a possible risk factor.
• Droplet spread: Human-to-human transmission is also possible via respiratory droplets usually requiring prolonged face-to-face contact.

6—16 days (range 5—21 days).

First week of rash.

• The clinical presentation is similar to the eradicated disease smallpox.
• The invasion period (0—5 days) is characterized by fever, intense headache, swelling of the lymph nodes, back pain, muscle ache and an intense lack of energy.
• The skin eruption period (within one to three days after the appearance of fever) where the various stages of the rash appear, often begins on the face and then spreads elsewhere on the body. The face (in 95 per cent of cases), and palms of the hands and soles of the feet (in 75 per cent of cases) are most affected. Evolution of the rash from maculopapules (lesions with a flat base) to vesicles (small fluid-filled blisters), pustules, followed by crusts occurs in approximately ten days which may last up to three weeks.
• Some patients develop severe swollen lymph nodes before the appearance of the rash, which is a distinctive feature of monkeypox compared to other similar diseases.
• Although the clinical manifestation of monkeypox is milder than that of smallpox, the disease can kill up to 11 per cent of infected people. Complications are respiratory distress, secondary bacterial infections and encephalitis.

Smallpox, varicella (chickenpox), measles, bacterial skin infections, scabies, syphilis and medication-associated allergies.

• Serology: IgM and IgG antibodies detection by enzyme-linked immunosorbent assay (ELISA).
• Antigen detection tests.
• Polymerase chain reaction (PCR).
• Virus isolation by cell culture.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of a treatment or vaccine should be conducted by a health professional.

• There are no specific treatments or vaccines available for monkeypox infection.
• Because monkeypox virus is closely related to the virus that causes smallpox, the smallpox vaccine can protect from getting monkeypox. Experts also believe that vaccination after a monkeypox exposure may help prevent the disease or make it less severe, if given soon after exposure. A new generation vaccine has been approved for prevention of smallpox and monkeypox since 2018. Following the worldwide eradication of smallpox, the smallpox vaccine is not available to the general public, but vaccine stockpiles are maintained by several countries and the World Health Organization (WHO).
• Pre-exposure smallpox vaccination for high-risk groups (e.g. public health workers investigating the outbreak, animal control or veterinarian workers, healthcare and laboratory workers, close contacts without contraindications) has been effective.
• Post-exposure smallpox vaccination (within four days of initial exposure to monkeypox) can be discussed in outbreak areas.

Past data suggest that the smallpox vaccine is at least 85 per cent effective in preventing monkeypox.