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Microbiology · Other DNA viruses

Mpox virus !

  • Virus
  • Enveloped
  • Contact
  • Airborne
  • Exam priority: medium

A poxvirus that causes skin and mucosal lesions with swollen lymph nodes; it caused worldwide outbreaks in 2022 and 2024.

Updated 2026-11-01

Also called: mpox, monkeypox

At a glance

Shape
Large, brick-shaped, enveloped
Genome
Linear double-stranded DNA
Envelope
Enveloped
Family
Poxviridae (genus Orthopoxvirus)
Size
About 200 to 250 nm

Morphology

  • Large brick-shaped virus
  • Replicates in the cytoplasm with its own machinery (cytoplasmic inclusion bodies)
  • Two clades: I (Ia, Ib) and II (IIa, IIb)

Transmission

  • Close skin-to-skin, mouth-to-skin and face-to-face contact, including sex
  • Contaminated objects (bedding, towels)
  • Mother to fetus or newborn
  • Infected animals (rodents) in endemic areas of Africa

Reservoir: African rodents (probable); Humans during outbreaks

Isolation precautions

What the care team adds to standard precautions.

Contact
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.
Airborne
N95 respirator and a negative-pressure room.

Virulence factors

  • Proteins that block interferon and complement
  • Clade I has historically been linked to higher fatality than clade II

Diseases it causes

Clinical picture

  • Fever, headache, muscle aches and prominent lymphadenopathy
  • Lesions moving from macule to papule, vesicle, umbilicated pustule and crust; in 2022 often anogenital and oral
  • Proctitis and severe pain from mucosal lesions that may not be visible
  • Symptoms start 1 to 21 days after exposure and last 2 to 4 weeks

Diagnosis

  • PCR of lesion material (including lesions in the mouth, anus or vagina)
  • Testing for HIV and other sexually transmitted infections, because another STI does not rule out mpox

Treatment

Supportive care and early pain control. Tecovirimat, approved for smallpox, is kept for severe disease or high-risk patients, although clinical trials have not shown a clear benefit.

Drug class only; doses and regimens are set by the clinician from the current guideline.

Prevention

  • Non-replicating modified vaccinia (MVA) vaccine for high-risk people and after exposure
  • Avoiding close contact with people who have lesions
  • In hospital: single room, gown, gloves, eye protection and an N95 respirator; an airborne isolation room for aerosol-generating procedures

Vaccine: Non-replicating MVA vaccine, aimed at high-risk groups and contacts; not part of the routine PAI schedule.

Test yourself

Think of the answer, then tap the question to see it.

Which clinical finding helps tell mpox from smallpox?

Prominent lymphadenopathy, present in mpox and absent in smallpox.

Which clade caused the 2022 worldwide mpox outbreak?

Clade IIb, spread mostly through close and sexual contact.

Which protective equipment do health workers use with an mpox patient?

Gown, gloves, eye protection and an N95 respirator, in a single room.

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← Back to the group: Other DNA viruses

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Mpox (WHO, 2025); Clinical Overview of Clade I and Clade II Monkeypox (CDC, 2025); Infection Prevention and Control in Healthcare Settings (CDC, 2025); Bogotá no presenta casos activos de viruela símica o del mono: Sec. de Salud (Alcaldía de Bogotá, 2023).

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Representative model, for educational purposes only.