Monkeypox virus infection case definition

This page contains the case definitions for monkeypox virus infection which is nationally notifiable within Australia. This definition should be used to determine whether a case should be notified.

Page last updated: 05 June 2022

Reporting

Both confirmed cases and probable cases should be notified. A suspected case definition has been developed in response to the current multi-country outbreak of monkeypox virus infection in non-endemic countries and may be discontinued as the outbreak evolves. Suspected cases should not be notified to the National Notifiable Disease Surveillance System (NNDSS) but should be reported to state and territory public health units.

Confirmed case

A confirmed case requires laboratory definitive evidence only

Laboratory definitive evidence

  1. Detection of monkeypox virus by nucleic acid amplification testing in clinical specimens

OR

  1. Detection of monkeypox virus-specific sequences using next generation sequencing for clinical specimens

OR

  1. Isolation of monkeypox virus by culture from clinical specimens

Probable case

A probable case require laboratory suggestive evidence AND clinical evidence

Laboratory suggestive evidence

  1. Detection of Orthopoxvirus by nucleic acid amplification testing in clinical specimens

OR

  1. Detection of Orthopoxvirus by electron microscopy from clinical specimens in the absence of exposure to another orthopoxvirus

Clinical evidence

A clinically compatible illness with rash1, 2,3 on any part of the body with or without one or more classical symptom(s) of monkeypox virus infection:

  • lymphadenopathy
  • fever (>38C) or history of fever
  • headache
  • myalgia
  • arthralgia
  • back pain

Suspected case3

A suspected case requires clinical evidence4 AND epidemiological evidence

Clinical evidence

As for probable case

Epidemiological evidence

  1. An epidemiological link to a confirmed or probable case of monkeypox virus infection in the 21 days before symptom onset

OR

  1. Overseas travel in the 21 days before symptom onset

OR

  1. Sexual contact and/or other physical intimate contact with a gay, bisexual or other man who has sex with men in the 21 days before symptom onset

Notes

  1. Lesions typically begin to develop simultaneously and evolve together on any given part of the body, and may be generalised or localised, discrete or confluent. The evolution of lesions progress through four stages – macular, papular, vesicular, to pustular – before scabbing over.
  2. For which the following causes of acute rash do not explain the clinical symptoms: chickenpox, shingles, measles, herpes simplex, or bacterial skin infections.
  3. Public health units should seek advice from the responsible authorising pathologist and the clinician regarding testing for monkeypox virus and other alternative causes.
  4. A high or medium risk contact of a confirmed or probable case only requires one or more symptoms of a clinically compatible illness (i.e. does not require rash, if another symptom present) to be a suspected case.