Virus

Monkeypox

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Monkeypox, Monkey Pox, Monkeypox Virus, Human Monkeypox, Monkeypox Virus Infection

  • Pathophysiology
  1. Virus in the Orthopoxvirus genus (same genus as Smallpox and Cowpox)
  2. Viral Infection whose natural hosts are primates and rodents
    1. Primarily in the tropical forests of West and Central Africa (esp. Congo Basin)
  3. Transmission to humans from animals is typically via bites or contact with the animal's blood
  4. Human to human transmission (much less common than with Smallpox)
    1. Respiratory transmission (primary route)
    2. Contact with infectious skin lesions
  5. Outbreaks
    1. Originally limited to Democratic Republic of Congo (and Refugees and Immigrants from that region)
    2. Cases seen primarily in Africa (e.g. Cameroon, Liberia, Nigeria, Sierra Leone) with rare reported cases in Europe
    3. Isolated outbreak occurred in U.S. in 2003, related to rodents imported from West Africa
    4. In 2022, cases have been seen globally including the United States
  6. Course
    1. Incubation Period: 5 to 17 days
    2. Duration: 2 to 4 weeks
  • Types
  • Strains
  1. West African Monkeypox
    1. Milder illness with fewer deaths than with Central African Monkeypox
    2. Limited human-to-human transmission
  2. Central African Monkeypox Virus
    1. More severe cases with higher mortality
    2. Higher risk of person-to-person spread
  • Risk Factors
  1. Recent travel to endemic regions (esp. central and west african countries)
  2. Men who have Sex with Men
  • Findings
  1. Febrile Prodrome
    1. Fever
    2. Chills
    3. Malaise
    4. Headache
  2. Marked Lymphadenopathy (generalized or localized)
  3. Rash
    1. Characteristics
      1. Vesiculopustular rash
      2. Deep seated, firm, well-circumscribed lesions
      3. Lesions are of similar size to one another and are typically in same stage in a particular body region
      4. Lesions are painful until they crust or scab and begin to heal, at which time they are pruritic
    2. Distribution: Generalizes over first 24 hours as Centrifugal Rash (trunk is more spared)
      1. First: Tongue and mouth often show initial lesions
      2. Next: Face is often involved
      3. Next: Extremities (esp. Palms and soles)
      4. May also be found in perianal and genital regions (sexually transmitted)
    3. Lesions progress over a 2 to 4 week period
      1. Macule (1 to 2 days)
      2. Papule (1 to 2 days)
      3. Vesicles with clear fluid (1 to 2 days)
      4. Pustule with opaque fluid and Central DImple or umbilication (5 to 7 days)
      5. Crust or scab (7 to 14 days)
    4. Variations
      1. Lesion may coalesce into larger scabs
  • Labs
  1. Orthopoxvirus DNA PCR
    1. Preferred primary test in U.S.
  2. Orthopoxvirus Immunochemical stain
  3. Anti-Orthopoxvirus IgM
    1. Positive from day 5 to day 56 after rash onset
  • Differential Diagnosis
  1. Secondary Syphilis
  2. Herpes Simplex Virus
  3. Varicella Zoster Virus
  4. Chancroid
  5. Other Pox Viruses
    1. Smallpox
    2. Cowpox
  • Complications
  1. Hemorrhagic disease
  2. Sepsis
  3. Encephalitis
  • Management
  1. Supportive Care
  2. Antivirals
    1. Background
      1. Indicated in patients with high risk of severe disease (see prognosis below)
      2. These agents were primarily developed for use in Smallpox, and efficacy in Monkeypox is unclear
    2. Agents
      1. Tecovirimat (TPOXX, ST-246)
      2. Vaccinia Immune Globulin Intravenous (VIGIV)
      3. Cidofovir (Vistide, primary indication is for CMV Retinitis)
      4. Brincidofovir (CMX001, Tembexa)
  • Prognosis
  • High Risk Patients for Severe Disease
  1. Immunocompromised State
    1. Human Immunodeficiency Virus Infection (HIV or AIDS)
    2. Generalized Malignancy
    3. Leukemia
    4. Lymphoma
    5. Solid Organ Transplantation
    6. Immunosuppressants (e.g. Alkylating Agents, antimetabolites, Tumor Necrosis Factor Inhibitors, high-dose Corticosteroids)
    7. Status Hematopoietic Stem Cell Transplant (<24 months post-transplant or =24 months with graft-versus-host disease)
    8. Other Immunodeficiency (e.g. Autoimmune Condition)
  2. Other factors
    1. Age <8 years old
    2. Atopic Dermatitis
    3. Active exfoliative skin conditions (e.g. Eczema, burns, Impetigo, VZV, HSV, severe acne, severe Diaper Dermatitis, Psoriasis)
    4. Women in pregnancy or Lactation
  3. Disease complications
    1. Secondary Bacterial Skin Infection
    2. Gastroenteritis with severe Nausea, Vomiting, Diarrhea or Dehydration
    3. Bronchopneumonia
  • Resources
  1. McCollum (2020) Smallpox and Other Orthopoxvirus-Associated Infections, Yellow Book, Accessed 6/27/2022
    1. https://wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/smallpox-and-other-orthopoxvirus-associated-infections
  2. Monkeypox Response (CDC), Accessed 6/27/2022
    1. https://www.cdc.gov/poxvirus/monkeypox/response/2022/hcp/index.html
  3. Monkeypox Clinical Recognition (CDC), Accessed 6/27/2022
    1. https://www.cdc.gov/poxvirus/monkeypox/clinicians/clinical-recognition.html
  4. Monkeypox Treatment (CDC), Accessed 6/27/2022
    1. https://www.cdc.gov/poxvirus/monkeypox/clinicians/treatment.html