Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

For further information, see CMDT Part 32-08: Other Exanthematous Viral Infections

Key Features

  • Poxvirus infection with syndrome similar to smallpox

  • Incubation period ~13 days (range, 6–28 in one outbreak)

  • Mortality 3–11% depending on patient immune status; secondary attack rate ~10%

  • Enzootic in equatorial African rain forests, with limited person-to-person spread via exchange of body fluids or via droplets

  • Risk factors include rodent bite, working as a hunter, and being male > 18 years of age

  • First community-acquired outbreak in the United States occurred in 2003 in upper Midwest, apparently due to imported Gambian giant rats via consequent exposure of prairie dogs; other susceptible animals include nonhuman primates, rabbits, and rodents, including giant pouched rat in Central Africa (US federal agencies prohibit importation of African rodents)

  • In May 2022, an outbreak of monkeypox was identified in a number of countries globally that do not typically experience it, including cases in at least 10 states in the United States

  • The CDC response can be found at

Clinical Findings

  • Febrile prodrome

  • Lymphadenopathy

  • Rash distinguished by deep-seated and well-circumscribed nature, lesions at the same stage of development (unlike varicella but like smallpox), and centrifugal progression (including palms and soles)


  • Based on rash and lymphadenopathy (seen in ≤ 90% of unvaccinated persons)

  • Local and state public health officials and the CDC should be notified for assistance with confirmation of the diagnosis by

    • Electron microscopy

    • Viral culture

    • ELISA

    • PCR

    • GeneXpert MPX/OPX (monkeypox/orthopox) assay

  • Differential diagnosis includes varicella smallpox and varicella, but the rashes are generally distinct


  • Suspected cases should be placed on standard, contact, and droplet precautions

  • No standard or optimized guidelines for the clinical management of monkeypox exist

  • Cidofovir is effective in vitro, and its less toxic prodrug brincidofovir may be useful as well

  • Vaccinia immune globulin can be used in selected cases

  • Postexposure vaccination is advised for documented contacts of infected persons or animals

  • More information on treatment can be found at

  • General preventive measures include

    • Avoidance of contact with rodents from endemic areas (whose illness is manifested by alopecia, rash, and ocular or nasal discharge)

    • Appropriate care and isolation of humans exposed to such animals within the prior 3 weeks

    • Veterinary examination and investigation of suspect animals through health departments

  • Vaccinia immunization (MVA-BN)

    • Effective against monkeypox

    • Recommended for

      • Adults 18 and older involved in the investigation of an outbreak

      • Health care workers caring for those infected with monkeypox

      • Patients in whom no contraindication exists (ie, immunosuppression, eczema or other dermatitis in the vaccinee or household contacts, allergy to any component of the vaccine, and pregnancy or breastfeeding)

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.