Mpox

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Mpox (monkeypox) is an infectious disease caused by the Monkeypox virus of the Orthopoxvirus genus. It is endemic in West and Central Africa. In 2022, mpox spread to nonendemic regions and was declared a public health emergency of international concern by the WHO. In the wake of the 2022 epidemic, the WHO changed the name of the disease from monkeypox to mpox because of concerns about stigmatizing language. Mpox is primarily transmitted via skin-to-skin contact with lesions from an infected individual or from a bite or scratch from an infected animal. Clinical features include flu-like symptoms, lymphadenopathy, and a painful, vesicular rash that typically develops 1–4 days after the onset of fever. Diagnosis is confirmed by PCR from a sample of the lesion. Affected individuals generally recover within 2–4 weeks with supportive treatment. Individuals with severe disease may be treated with antivirals. Two vaccines are currently available for use against mpox.

• Endemic in West and Central Africa ^[2]
• Travel-associated outbreak in the UK in May 2022, with subsequent cases in continental Europe, North America, South America, and Australia ^[3]
• On July 23, 2022, the WHO declared the mpox outbreak a public health emergency of international concern. ^[4]

Epidemiological data refers to the US, unless otherwise specified.

• Pathogen: Monkeypox virus (dsDNA virus of the Orthopoxvirus genus in the family Poxviridae) ^[5]
• Reservoir: rodents and primates ^[6]
• Transmission
  • Human-to-human transmission
    • Contact through cutaneous or mucosal lesions and/or body fluids (e.g., sex, kissing, hugging, massaging)
    • Respiratory droplet transmission
    • Vertical transmission
    • Fomite transmission (e.g., from contaminated clothes, bed sheets)
  • Animal-to-human transmission: scratch or bite from an infected animal
• Incubation period: 5–21 days ^[2]
• High risk for mpox infection (risk factors and groups at risk)
  • High-risk sexual behavior
  • Men who have sex with men (MSM) with multiple partners ^[7]
  • Occupational exposure
  • Exposure to animal reservoirs

• Viral prodrome
  • Flu-like illness
  • Lymphadenopathy
  • Typically lasts 1–4 days
• Characteristic mpox rash ^[8]
  • Rash evolves sequentially: macules → papules → vesicles → pustules → umbilication → crusts → desquamation
  • Firm, well-circumscribed lesions measuring 0.5–1 cm in diameter
  • Initially painful, then pruritic
  • Typically lasts 2–3 weeks
• Upper respiratory
  • Sore throat
  • Odynophagia
  • Epiglottitis
  • Acute tonsillitis
• Genitourinary
  • Anorectal pain
  • Proctitis with bleeding
  • Penile edema, balanitis, phimosis

Diseases with a similar blistering appearance such as chickenpox and smallpox typically do not cause lymphadenopathy.

Perform a thorough clinical evaluation and obtain PCR testing if indicated.

While PCR testing alone is required to diagnose mpox, additional laboratory studies (e.g., CBC, CMP) can identify individuals with severe disease who have indications for inpatient management and/or antiviral therapy.

PCR testing ^[9][10][11]

Indications

• Characteristic mpox rash
• OR clinical suspicion and the presence of one or more of the following within 21 days of symptom onset:
  • Close or intimate contact with someone who has:
    • A similar rash
    • Confirmed or probable mpox
    • Risk factors for mpox infection
  • Travel to a country with mpox cases or to an endemic region
  • Contact with animals, or products derived from animals, known to carry mpox

Procedure

Contact the local or state health department for further guidance on testing.

• Isolate patients during evaluation.
• Obtain two separate swabs from multiple lesions (if present).
• Do not unroof lesions prior to swabbing.
• Send samples for nonvariola Orthopoxvirus PCR test.

Advise patients to remain isolated while awaiting test results, which may take 2–3 days.

• Chickenpox
• Smallpox
• Measles
• Syphilis
• Autoimmune blistering diseases
• Herpes zoster
• Scabies

The differential diagnoses listed here are not exhaustive.

Approach ^[8][10][11]

• Severe mpox (or risk factors for severe mpox)
  • Consult infectious diseases.
  • Consider antiviral treatment.
  • Monitor and treat in an inpatient setting.
• Mild or uncomplicated disease: outpatient management
• All patients
  • Provide supportive care.
  • Educate about infection prevention and control measures.
  • Report cases to the local department of health.

Severity assessment ^[8][10]

• Severe mpox ^[8][10]
  • Confluent skin lesions
  • GI signs/symptoms: e.g., dysphagia , nausea, vomiting, hepatomegaly
  • Laboratory markers ^[8]
    • CBC: leukocytosis, lymphocytosis, thrombocytopenia
    • Transaminitis
    • ↓ BUN
    • Hypoalbuminemia
  • Mpox complications: e.g., sepsis, pneumonia, bacterial superinfection
• Risk factors for severe mpox ^[8]
  • Age < 8 years
  • Pregnancy or breastfeeding
  • Immunosuppression (e.g., in individuals with poorly controlled HIV/AIDS, transplant, malignancy)
  • Preexisting or acute skin conditions (e.g., atopic dermatitis, burns)

Infection control ^[8][10]

Isolation recommendations may vary regionally and may change as the mechanisms of the spread of mpox infection are better understood.

• Isolation precautions
  • Outpatient: Isolate at home until the illness has resolved.
  • Hospitalized individuals: Isolate in a single-person room with a dedicated bathroom with:
    • Contact precautions and droplet precautions
    • Airborne precautions during aerosol-generating procedures
• Standard precautions
  • Frequent hand hygiene
  • Regularly clean shared surfaces (e.g., in the kitchen and bathroom).
  • Household members: Utilize face masks when within 6 feet of infected individuals.
  • Health care workers: Utilize personal protective equipment (i.e., gloves, gown, eye shield, and N95 respirator).
• Counseling on safer sex practices ^[8]
  • Sexual abstinence until all crusted lesions have healed
  • Consistent use of condoms for at least 12 weeks after recovery

Advise patients to avoid the following until all lesions have healed: close contact with people and animals, using contact lenses, shaving skin with lesions, and sharing household or personal items.

Patients are contagious until crusts have fallen off and new skin has formed.

Pharmacotherapy ^[10]

The following therapies can be used off-label under expanded access (compassionate use) protocols.

• Antiviral therapy
  • Indications
    • Severe mpox
    • Aberrant infections (e.g., involving the eye, mouth, genitals, anus)
    • Risk factors for severe mpox
  • Preferred agent: tecovirimat
  • Alternatives: cidofovir, brincidofovir
• Intravenous vaccinia immune globulin: unknown effectiveness but can be considered in severe cases

Supportive care for mpox ^[8][10]

• Skin lesions
  • Cleanse skin to avoid bacterial superinfection.
  • Avoid scratching.
  • Keep skin uncovered to air dry.
  • Consider sitz baths for anorectal or genital lesions.
  • Monitor for secondary skin and soft tissue infections.
  • Consider antihistamines (e.g., loratadine ) as needed for pruritus. ^[8]
• Oral lesions
  • Rinse with salt water as needed.
  • Rinse with oral antiseptic (e.g., chlorhexidine mouthwash).
  • Consider viscous lidocaine for painful oral lesions. ^[8]
• Additional considerations
  • Encourage adequate oral nutrition and fluid intake.
  • Start pain management according to the WHO analgesic ladder.
  • Offer antiemetics (e.g., off-label ondansetron ) and antipyretics (e.g., acetaminophen ) as needed. ^[8]

• Sepsis or septic shock
• Dehydration
• Pneumonia
• Encephalitis
• Bacterial superinfection (e.g., cellulitis, abscess, necrotizing soft tissue infection)
• Pyomyositis
• Blindness (following corneal infection)
• Acute respiratory distress syndrome
• Hemorrhagic disease

We list the most important complications. The selection is not exhaustive.

• Affected individuals typically recover within 2–4 weeks. ^[2]
• Mortality: 1–10% (esp. children and immunocompromised individuals)

Primary prevention ^[12][13]

Two live Vaccinia virus vaccines are available.

• Preparations
  • JYNNEOS: 2 doses given 4 weeks apart (vaccine is effective 2 weeks after the second dose)
  • ACAM2000: single dose (vaccine is effective after 28 days)
• Indications
  • Occupational exposure
  • Exposure to animal reservoirs
  • Sexual exposure
    • Bisexual, gay, or other MSM, and transgender or nonbinary individuals with an STI and/or ≥ 1 sex partner within the past 6 months
    • Individuals who have had sex at a commercial sex venue and/or sex in association with a large public event in an area with a known mpox outbreak within the past 6 months
    • Sexual partners of any of the above individuals
  • Immunosuppression and recent or anticipated potential exposure to mpox

Secondary prevention ^[10][12]

Mpox postexposure prophylaxis

• Vaccination
  • Indications
    • Known contact with an individual with mpox
    • Sexual partner diagnosed with mpox
    • Bisexual, gay, or other MSM, and transgender or nonbinary individuals at high risk of exposure within the past 14 days
  • Timing: ideally within 4 days of exposure, but still effective 4–14 days after exposure
• Ring vaccination: used in the 2022 mpox outbreaks in different parts of the world
• Vaccinia immune globulin: for individuals with severe T-cell immunodeficiency in whom vaccination is contraindicated

Monitoring for clinical features of mpox

• Indication: all patients with any known mpox exposure
• Duration: 21 days
• Activity restrictions are not required during monitoring.
• If symptoms develop, individuals should isolate until evaluation by a health care provider.