II. 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. 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)
  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

III. 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

IV. Risk Factors

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

V. 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. 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. 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

VI. 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

VIII. Complications

  1. Hemorrhagic disease
  2. Sepsis
  3. Encephalitis

IX. 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. Tecovirimat (TPOXX, ST-246)
      2. Vaccinia Immune Globulin Intravenous (VIGIV)
      3. Cidofovir (Vistide, primary indication is for CMV Retinitis)
      4. Brincidofovir (CMX001, Tembexa)

X. 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

XI. Prevention

  1. Lesions are often outside of Condom protection
  2. Limit sexual partners
  3. Vaccination
    1. Preparations
      1. JYNNEOS (preferred, approved for Monkeypox)
      2. ACAM2000 (Smallpox Vaccine)
        1. Adverse effects include Myocarditis
    2. Post-exposure Prophylaxis
      1. Ideal if within 4 days of exposure
      2. May be given up to 14 days after exposure

XII. Resources

XIII. References

  1. (2022) Presc Lett 29(9): 49-50

Images: Related links to external sites (from Bing)

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).
Definition (MSH) A viral disease infecting PRIMATES and RODENTS. Its clinical presentation in humans is similar to SMALLPOX including FEVER; HEADACHE; COUGH; and a painful RASH. It is caused by MONKEYPOX VIRUS and is usually transmitted to humans through BITES or via contact with an animal's BLOOD. Interhuman transmission is relatively low (significantly less than smallpox).
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

Ontology: Human monkeypox (C1282998)

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

Ontology: Monkeypox Virus Infections (C1456660)

Definition (MEDLINEPLUS)

Monkeypox is a rare viral disease. It occurs mostly in central and western Africa. Wild rodents and squirrels carry it, but it is called monkeypox because scientists saw it first in lab monkeys. In 2003, it was reported in prairie dogs and humans in the U.S.

Centers for Disease Control and Prevention

Concepts Disease or Syndrome (T047)
English Monkeypox Virus Infections