Mpox

Introduction

Mpox (previously referred to as monkeypox) is a viral zoonotic infection that results in a rash similar to that of smallpox.

  • However, historically, person-to-person spread outside the household and mortality from mpox are significantly less than for smallpox.

Clinically, these 2 viral infections are difficult to distinguish.

  • The virus belongs to the genus Orthopoxvirus in the family Poxviridae (other family member includes variola - causative agent of smallpox).
  • It was first isolated in 1958 from a colony of sick monkeys.

NOTE: Any case represents a public health emergency and suspicion of smallpox warrants immediate contact of local health departments.



Transmission

The virus can be acquired through contact with an infected animal's bodily fluids or through a bite.

  • It can also be acquired through preparation of bushmeat (raw or minimally processed meat that comes from wild animals in certain regions of the world, including Africa).
  • Monkeys and humans are incidental hosts; the reservoir remains unknown but is likely to be rodents.

Also, human-to-human transmission can occur in several ways:

  • Primarily direct contact with infectious sores, scabs or body fluids
  • Indirect contact through contact with materials or fomites that have become contaminated with infected material in the household or patient care environment, such as clothing or linens contaminated with infectious material from body fluids or sores
  • Vertical transmission from the mother to her foetus
  • Risk of spread through respiratory secretions, semen, vaginal fluids, or other body fluids is unclear.

The incubation period of monkeypox virus infection is usually from 5 to 13 days, but can range from 4 to 21 days.



Symptoms

Prodromal phase (1-5 days) characterized by abrupt onset of systemic symptoms such as fever, muscle aches, fatigue and headache.

Skin lesions (exanthem) begin on face and appear on all parts of body within 24-48 hours.

  • Crusting of lesions completed in 2-3 weeks
  • The rash associated with mpox is often described as painful, but in the healing phase (crusts), it can become itchy.

Monkeypox



Management

Monkeypox is usually a self-limited disease with the symptoms lasting from 2 to 4 weeks.
  • Many immunocompetent patients with mpox have mild disease and will recover without medical intervention.
  • However, some patients may require pain relief medications (e.g. paracetamol, NSAIDs, or topical anaesthetics).
  • Supportive care requiring hospitalization may be warranted for those who have or are at risk for dehydration (e.g., nausea, vomiting, dysphagia, severe tonsillitis), those who require more intensive pain management, and those experiencing severe disease or complications.

Several antivirals may be useful for the treatment of mpox.

  • At this time, tecovirimat is the treatment of choice.



Prevention

Isolate persons with suspected or confirmed mpox from others (until all lesion scabs have fallen off and re-epithelialization has occurred, which typically lasts 2-4 weeks).

  • If around others, skin lesions should be covered (e.g., long sleeves, long pants) to minimize risk of contact with mpox lesions.
  • Patients should avoid sharing their used clothes, towels, food, utensils, or face masks with others and should not allow animals to access them.
  • Individuals with mpox should wear a well-fitting facemask when around others, even if respiratory symptoms are not present. Ideally, household members should wear a facemask when in the presence of the person with mpox as well.

Household members providing care to patients with mpox should use disposable gloves for direct contact with lesions.

  • The gloves should be disposed of after use, followed by hand hygiene with an alcohol-based hand rub or, if visibly soiled, with soap and water.

Care should be used when handling soiled laundry to avoid direct contact with contaminated material.

  • Laundry may be washed in a standard washing machine with water and detergent.

There are two available vaccines that can reduce the risk of developing mpox.

  • The modified vaccinia Ankara (MVA) vaccine (JYNNEOS in the United States, IMVANEX in the European Union, and IMVAMUNE in Canada) and ACAM2000 vaccine.



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