II. Epidemiology

  1. Outbreak 2022 spring globally (including U.S.), 98% of 528 cases studied were in Men who have Sex with Men
    1. Of these cases, 95% of transmission occurred during sex
    2. Thornhill (2022) N Engl J Med 387(8): 679-91 [PubMed]
  2. 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

III. 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 with prolonged, close face-to-face contact (primary route)
    2. Mucous membrane or body fluid contact with broken skin
      1. Sexually Transmitted Infection especially among Men who have Sex with Men
      2. Receptive anal intercourse appears to be a common mode of transmission
    3. Contact with infectious skin lesions (or contaminated clothing or bedding)
      1. Unlikely with brief contact (e.g. touching a doorknob or sitting on a toilet seat)
      2. Lesions are infectious until they re-epithelialize
  5. Course
    1. Incubation Period: 7 to 10 days (range 5 to 17 days)
    2. Duration: 2 to 4 weeks

IV. 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

V. Risk Factors

  1. Recent travel to endemic regions (esp. central and west african countries)
  2. Men who have Sex with Men (esp. multiple partners)

VI. Findings

  1. Onset up to 21 days after exposure
  2. Febrile Prodrome
    1. Fever
    2. Chills
    3. Malaise or Fatigue
    4. Headache
    5. Pharyngitis
  3. Marked Lymphadenopathy (generalized or localized)
  4. Common focal lesions are often sexually transmitted (oral sex, receptive anal sex)
    1. Tonsillitis
    2. Anogenital lesions (vessicle, Pustules, or firm well circumscribed ulcers)
    3. Proctitis
      1. May present with Rectal Pain and non-bloody Diarrhea
  5. Rash
    1. Characteristics
      1. Vesiculopustular rash (Blisters, Pustules)
      2. Deep seated, firm, well-circumscribed lesions that may be umbilicated, and are larger than Shingles or HSV 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. Initial Lesions
        1. Tongue or mouth lesions or Tonsillitis (often related to oral sex)
        2. Perianal and genital regions (sexually transmitted, often related to receptive anal intercourse)
      2. Next: Face is often involved
      3. Next: Extremities (esp. Palms and soles)
    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

VII. 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

IX. Complications

  1. Hemorrhagic disease
  2. Sepsis
  3. Encephalitis

X. Management

  1. Supportive Care
  2. Consult with local public health regarding testing and treatment
  3. Isolation for 2 to 4 weeks until rash fully heals
    1. When around others, mask and cover wound with dressing
  4. Antivirals
    1. Background
      1. Indicated in patients with high risk of severe disease, esp. Immunocompromised, and anogenital lesions (see prognosis below)
      2. These agents were primarily developed for use in Smallpox, and efficacy in Monkeypox is unclear
    2. Agents
      1. Vaccinia Immune Globulin Intravenous (VIGIV)
      2. Cidofovir (Vistide, primary indication is for CMV Retinitis)
      3. Brincidofovir (CMX001, Tembexa)
      4. Tecovirimat (TPOXX, ST-246)
        1. IV: 200 mg IV every 12 hours for weight >40 kg (300 mg IV if weight >120 kg)
        2. Oral: 600 mg orally every 12 hours for weight > 40 kg (every 8 hours for weight >120 kg)
        3. IV formulation is contraindicated in Creatinine Clearance <30 ml/min
        4. Adverse effects include Nausea, Vomiting and Abdominal Pain (and uncommon Allergic Reactions)
        5. Unknown safety in pregnancy, but limited systemic absorption
        6. LoVecchio (2022) Crit Dec Emerg Med 36(10): 32

XI. 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

XII. Prevention

  1. Lesions are often outside of Condom protection
  2. Limit sexual partners
  3. Vaccination
    1. Preparations
      1. JYNNEOS (preferred, approved for Monkeypox)
        1. Two dose Vaccine (28 days apart)
      2. ACAM2000 (Smallpox Vaccine)
        1. Adverse effects include Myocarditis
        2. Not recommended for Immunocompromised patients
    2. Indications
      1. Occupational exposure (e.g. lab workers)
      2. Post-exposure Prophylaxis (sexual or other close contact)
        1. Ideal if within 4 days of exposure
        2. May be given up to 14 days after exposure
      3. High risk patients in regions of Monkey Pox outbreaks
        1. Men who have Sex with Men
        2. Multiple sexual partners

XIII. Resources

XIV. References

  1. (2022) Presc Lett 29(9): 49-50
  2. Marx (2022) Crit Dec Emerg Med 36(11): 12-3

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Related Studies

Ontology: Monkeypox virus (C0026432)

Definition (MSH) A species of ORTHOPOXVIRUS causing an epidemic disease among captive primates.
Concepts Virus (T005)
MSH D008993
SnomedCT 59774002
English Monkey Pox Virus, Monkey Pox Viruses, Monkeypoxvirus, Monkeypoxviruses, Monkeypox virus, monkeypox virus, monkey pox virus, Monkeypox viruses, Monkeypox virus (organism)
Swedish Apkoppsvirus
Czech virus neštovic opic
Finnish Apinarokkovirus
French Monkeypoxvirus, Virus de la variole du singe, Virus de la variole simienne, Monkeypox virus, Monkey pox virus
Japanese サル痘ウイルス, 猿ポックスウイルス, 猿痘ウイルス
Polish Wirusy ospy małp
Spanish Virus Monkeypox, Virus de la Viruela de los Monos, virus de la pustulosis de los monos, virus de la viruela de los monos (organismo), virus de la viruela de los monos, Virus de la Viruela del Simio
Portuguese Poxvirus do Macaco, Vírus da Varíola dos Símios, Vírus Monkeypox, Vírus da Varíola dos Macacos
German Affenpocken-Virus
Italian Virus del vaiolo delle scimmie
Dutch Apenpokkenvirus, Virus, Apenpokken-

Ontology: Monkeypox (C0276180)

Definition (MSHFRE) Maladie virale retrouvée ches les primates et les rongeurs. Chez l'homme, les symptômes cliniques sont identiques à ceux de la variole incluant fièvre, cépalées, toux et éruption douloureuse. La maladie est due au virus monkeypox ou virus de la variole du singe, elle est habituellement transmise à l'homme par morsures ou par contact avec le sang de l'animal infecté. La transmission interhumaine est relativement faible (significativement moindre que la variole).
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Concepts Disease or Syndrome (T047)
MSH D045908
ICD9 059.01
ICD10 B04
SnomedCT 186582008, 240466002, 25157001, 359814004, 359811007
Spanish Viruela de los Simios, Viruela del mono, viruela de los monos (trastorno), viruela de los monos en los humanos, viruela de los monos, Viruela Simia, Viruela Símica, Viruela del Simio, viruela de los monos (concepto no activo), viruela del mono, viruela del simio (trastorno), viruela del simio
Swedish Apkoppor
Finnish Apinarokko
English monkeypox, monkeypox (diagnosis), Monkeypox [Disease/Finding], monkey pox, Monkeypox, Monkey Pox, Monkey pox, Monkeypox (disorder), Monkeypox (disorder) [Ambiguous]
Japanese サル痘, 猿痘, サルトウ
Korean 원숭이두창
Portuguese Varíola dos macacos, Varíola dos Macacos, Varíola do Macaco, Monkeypox
Dutch apenpokken, Apenpokken, Monkeypox
Czech Opičí nemoc, opičí neštovice, neštovice opic
Polish Ospa małpia, Ospa wietrzna małp
Hungarian Majomhimlő
Norwegian Monkeypox, Apekopper
French Orthopoxvirose simienne, Variole du singe, Monkey Pox, Monkeypox
German Affenpocken
Italian Monkeypox

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Concepts Disease or Syndrome (T047)
SnomedCT 359811007, 25157001
English Human monkeypox (disorder), Human monkeypox
Spanish viruela del simio en el humano (trastorno), viruela del simio en el humano

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Definition (MEDLINEPLUS)

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Centers for Disease Control and Prevention

Concepts Disease or Syndrome (T047)
English Monkeypox Virus Infections