MPOX is a zoonosis caused by the virus Monkeypox (orthopoxvirus), related to that of smallpox. There are two clades: clade I, highly contagious and virulent, and II, which circulates quietly in Europe.
Between January and June 2024107 cases have been reported in France, all due to clade II and having had a benign evolution. One case due to clade I has been reported in Europe, in Sweden. It is likely that clade I infections will remain sporadic in France. The country is preparing for this. It is in this context that the Health Insurance published a 4-part focus on this disease.
Transmission
Transmission of the virus to humans occurs initially through contact with a reservoir animal (rodents, monkeys). Human-to-human transmission occurs in two ways:
- By direct contact with the lesions of an infected person (skin, mouth, anus, genitals). Condoms do not protect against this.
- By prolonged face-to-face contact with respiratory droplets or by contact with objects contaminated by the patient (clothing, linen, etc.).
Contamination occurs from the onset of symptoms until the lesions heal.
Symptoms and diagnosis
The incubation period is 5 to 21 days. The disease begins with a fever above 38 °C and the appearance of numerous large painful lymph nodes, myalgia and asthenia. One to three days later, a widespread skin rash appears, initially localized on the face, then spreading within 24 hours to the entire body to the palms of the hands and soles of the feet. Localization at the level of the mucous membranes of the anus, genitals and mouth is common.
Skin lesions begin as macules, progressing to painful papules, then to vesicles with clear fluid, then to sharp, firm pustules that become sunken and ulcerated, ending in scabs, which fall off once dry.
The diagnosis is suspected by questioning, which looks for possible contact with the virus (stay in an endemic area, contact with an infected person). It is confirmed by a PCR test on swab samples, preferably mucous (nose, throat or genital and anal lesions), but also skin at the level of vesicles or pustules. If the mpox was transmitted by sexual contact, an STI assessment is requested immediately (HIV, hepatitis B, hepatitis C, syphilis, gonococcus and chlamydia).
COPD is a notifiable disease.
Evolution
Most often, the disease heals within two to four weeks. Complications are possible: major rashes with fusion of skin lesions and skin loss, severe pain, epiglottitis, bacterial superinfection of skin lesions, meningoencephalitis, etc.
The risk of death is currently 1% in Europe, but it can reach 10% with clade I, with most deaths occurring in young patients.
Smallpox vaccination (before its abolition in 1977) partially protects against COPD.
Treatment
Anyone with MPOX infection should wear a surgical mask until they are healed whenever they are in the presence of another person and gloves when touching objects shared with other people. Hand washing should be frequent.
The patient must isolate himself at home, if possible alone in a dedicated room, for at least 3 weeks from the date of onset of symptoms until complete healing of the skin lesions. He must abstain from any sexual contact, even with a condom, and not share linen and clothes with other family members. People with severe forms must be hospitalized.
The drug treatment is that of fever (paracetamol). Non-steroidal anti-inflammatory drugs, corticosteroids and aspirin are contraindicated.
Skin lesions are cleaned by washing with soap and water. Antihistamines may be prescribed. Disinfection with chlorhexidine is necessary in the event of bacterial superinfection. Antiviral treatment is not systematically necessary. It is decided by a multidisciplinary hospital team.
People caring for patients must wear an FFP2 mask and waterproof gloves to touch any object that has been in contact with them (glasses, towels, clothes, etc.). A search for contact cases must be carried out.
Vaccination
Post-exposure vaccination with a 3rd generation vaccine (Imvanex or Jynneos) is offered to adult contacts at risk, including healthcare professionals exposed without personal protective measures. The vaccine is ideally administered within 4 days after the risky contact and a maximum of 14 days later with a 2-dose schedule (or 3 doses in immunocompromised subjects), spaced 28 to 35 days apart.
