mpox

Overview

A global outbreak of mpox (formerly known as monkeypox) clade II started in 2022, with increased numbers of cases occurring in Australia during 2022 and 2024. Within this outbreak, mpox infection has almost exclusively been diagnosed among men who have sex with men, transmitted through sexual contact and other similarly close contact. As cases continue to occur in many countries, there is an ongoing risk within Australia.
A separate clade I outbreak commenced in 2023 in some African countries. Clade I infections are associated with greater disease severity. There have been very few cases of clade I detected in Australia, and no evidence of sustained transmission to date.
Most mpox cases are mild and self-limiting, but severe infection and complications can occur, especially in people who are immunocompromised.
Mpox is vaccine-preventable using JYNNEOS (a brand name of replication-deficient modified vaccinia Ankara– Bavarian Nordic, or MVA-BN). Information about the vaccine can be obtained from the Australian Immunisation Handbook. Vaccination is available from sexual health clinics and some general practitioners and pharmacies, seek further advice from your local public health service.
Vaccination against mpox is recommended for groups at risk of exposure. This includes:
- gay, bisexual or other men who have sex with men (GBMSM), including transgender and gender-diverse people
- sex workers, particularly those whose clients are at risk of mpox exposure
- people with HIV, if at risk of mpox exposure 
- other individuals whose sexual networks might include GBMSM
- laboratory personnel working with orthopoxviruses
- Vaccination may also be considered for healthcare workers at risk of exposure to patients with mpox
- Post-exposure preventive vaccination is recommended for anyone categorised by public health authorities as a high-risk mpox contact within the past 14 days.
- A standard primary vaccination course of MVA-BN mpox vaccine requires 2 subcutaneous doses, each of 0.5 mL, given 4 weeks apart. Subcutaneous injection is the preferred route of administration.

Symptoms
Lesions which can be painful on skin and mucosal surfaces. Lesions evolve from macules, to papules, to vesicles, to pustules, to crusted scabs. Typically last 3 weeks, but can be longer.
Proctitis, anal pain and/or anal bleeding.
Prodromal symptoms: Generalised centrifugal rash, fever, lymphadenopathy, headache, muscle pain, joint pain, back pain. Typically last up to 5 days.
Asymptomatic infection is rare.
Complications
Secondary bacterial cellulitis of affected skin or mucosal surfaces (common)
Severe pain from lesions. Anorectal pain may require management in hospital (uncommon)
Dehydration due to vomiting, diarrhoea, and/or oral lesions preventing oral intake (uncommon)
Sepsis (less common)
Pneumonia (rare)
Encephalitis (rare)
Keratitis, leading to permanent vision loss (rare)

See ASHM’s mpox page for images.

Special considerations

Complications are more common in people who are immunocompromised, such as people living with HIV with a CD4 count < 200 cells/uL.

Site/Specimen	Test	Consideration
Lesion fluid	NAAT of dry swab	Ideally collected when a vesicle or pustule is de-roofed
Lesion tissue or crust	NAAT of material in dry container	Best test if no fluid-filled vesicles or pustules are available for testing
Skin biopsy	NAAT of skin biopsy in dry container	Alternative test if no vesicles, pustules or crusts are available for testing
Anorectal swab	NAAT of dry swab	Alternative test if patient presents with anal symptoms and cannot tolerate anoscopy for collection of sample under direct vision. Not recommended for use without symptoms

NAAT – Nucleic acid amplification test

Specimen collection guidance: Clinician collected | Self-collection

Contact your local laboratory prior to specimen collection to check the availability of mpox tests (NAAT). Alternatively, contact your nearest hospital laboratory to arrange transport of specimen(s).
Dry swab transport tubes are the preferred option to avoid the risk of leakage during transport and allows for laboratory staff to process the specimen appropriately. However, if swabs in VTM or liquid Amies is being used please ensure the lid is appropriately secured. Use of bacterial culture swabs (e.g. containing gel media for bacterial preservation) is not acceptable to perform NAAT testing.
Where there are distinct anatomical or morphological lesions consider swabbing at least 2 lesions with separate swabs, and write the lesion site on the specimen containers.
If no lesion fluid is available for collection, then dry crusts or biopsy material can be tested; to be transported in a dry container.
Wear adequate PPE, including gown, gloves, surgical mask, and eye protection.
Avoid contact with contaminated materials (e.g., bedding).

Investigations

Public laboratories have implemented mpox-specific PCR/NAAT assays.
Some laboratories may still use Orthopox PCR/NAAT assays instead.
Some commercial laboratories do not have a specific assay.

Clinical indicators for testing

Testing is only indicated when patients present with symptoms suspected of being due to mpox virus.
Asymptomatic screening, or testing asymptomatic contacts for mpox is not recommended, as asymptomatic carriage appears rare.

Special considerations

Swab suspected mpox lesions for HSV PCR, syphilis PCR, and LGV PCR, as these are important differential diagnoses.
Consider swabbing suspected mpox lesions for M/C/S, as secondary bacterial cellulitis is common.
Perform full HIV/STI screen at time of presentation, as co-infection with HIV/STIs is common.

Principal treatment options
Situation	Recommended
Uncomplicated mpox virus infection	Supportive treatment, including analgesia, antibiotics for secondary cellulitis, and stool softeners for anal lesions.
Severe mpox virus infection, or in those at risk of severe infection (e.g., CD4 < 200 cells/uL), or in those with complications (e.g. eye infection, severe secondary cellulitis)	Discuss with an infectious diseases or sexual health specialist whether antiviral and/or immunoglobulin (VIG) treatment is indicated.

Treatment advice

Most cases are mild and self-limited, and do not require specific antiviral therapy.
Patients who may require antiviral therapy should be discussed with an infectious diseases physician or sexual health physician. Indications for urgent discussion with a specialist include: (1) severe mpox disease (e.g. sepsis, encephalitis, eye infection); (2) one or more complications (e.g. secondary cellulitis, dehydration, pneumonia); or (3) those at risk of severe disease (e.g. immunocompromise such as CD4 count < 200 cells/uL, children, pregnancy, breastfeeding). See Australian Human Monkeypox Treatment Guidelines for more detail.
Tecovirimat was made available through the National Medical Stockpile based on in vitro data however two subsequent randomised controlled trials did not demonstrate clinical benefit. Nonetheless people at significantly increased risk of severe disease should be discussed with an export as treatment may still be advised for some people. Common adverse effects of tecovirimat include headache, nausea, abdominal pain and vomiting, but it otherwise appears safe.
Vaccinia immunoglobulin (VIG) is held in the National Medical Stockpile in limited quantities. For toxicity, precautions and contraindications, see the Australian Human Monkeypox Treatment Guidelines.
Patients who need to be admitted to hospital should be discussed with the receiving infectious diseases team prior to transport to hospital, to ensure that appropriate biocontainment strategies can be enacted.
Consider early initiation of empiric antibiotics if secondary cellulitis is suspected.
Consider strong analgesia for mpox lesions in troublesome areas such as the oropharynx and anorectum.
Painful lesions may benefit from topical lignocaine.
Anal lesions may benefit from stool softeners.
Best-practice wound care for mpox lesions is important to reduce the risk of cellulitis.

For more information, see the Australian Human Monkeypox Treatment Guidelines.

Other immediate management

The risk of occupational transmission is minimal if healthcare workers follow the ICEG interim guidance on monkeypox
Upon clinical suspicion of mpox, immediately phone the local public health unit for advice on exclusions and restrictions during their infectious period before the patient leaves the clinic. See CDNA National Guidelines for Public Health Units on Monkeypox Virus Infection.
Cases are considered infectious until scabs have fallen off and a fresh layer of skin has formed.
Cases with anal pain/bleeding are considered infectious until their anal symptoms have completely resolved.
Monkeypox viral DNA has been found in the semen of men who have recovered from clinical mpox disease. This raises the possibility that mpox could be transmitted via semen for some weeks following clinical infection. However, to date there have been no definitive mpox transmissions via semen from someone who has recently recovered from mpox. For this reason, people who have a penis and who have recently recovered from mpox may wish to use condoms for some time after recovery from their mpox infection to reduce the risk of transmission to sexual partners who have not been vaccinated or previously infected.
Immunocompromised people are at higher risk of complications of mpox infection. Closely monitor PLHIV with a CD4 count < 200 cells/uL, or with an AIDS diagnosis in the preceding six months, or with persistent HIV viraemia (HIV VL > 200 copies/mL). For a full list of relevant immunocompromising conditions, see the Australian Human Monkeypox Treatment Guidelines.
Pets are at risk of infection and this risk should be considered during isolation, and may need to be re-housed temporarily to avoid the risk of mpox transmission to the pet.

Special considerations

Consider seeking specialist advice before treating any complicated presentation.

Situation	Recommended
Complicated or severe infection	Consider antiviral treatment and hospitalisation, after discussion with a specialist.
Immunocompromised people	Consider antiviral treatment and hospitalisation, after discussion with a specialist.
Pregnant people	Patients who are pregnant or breast feeding should be considered for specific mpox treatment. In pregnancy, VIG may be preferred over Tecovirimat.
Children (especially if < 10 years old)	Discuss with an infectious disease paediatrician, as children are at increased risk of severe infection.

Seek immediate local Public Health Unit assistance with contact tracing.
Contacts are stratified as low-risk, medium-risk, or high-risk, as described in the CDNA National Guidelines for Public Health Units on Monkeypox Infection.
Medium and high-risk contacts should be offered post-exposure vaccination with a subcutaneous dose of 3^rd-generation vaccinia vaccine (i.e., MVA), ideally within 4 days of last contact, but up to 14 days of last contact. Post-exposure vaccination more than 4 days after last contact may not prevent infection, but it may attenuate disease severity.
Contacts who receive post-exposure vaccination should receive a subcutaneous vaccine dose at least 28 days after their initial subcutaneous dose, unless they develop mpox infection in the interim.
For isolation and post-exposure vaccination advice for contacts, see CDNA National Guidelines for Public Health Units on Monkeypox Virus Infection.

Depending on clinical severity, arrange regular clinical reviews by telehealth while the patient is isolating to assess progress of recovery, emergence of complications, and need for assistance with isolation.
Patients with laboratory-confirmed mpox infection are considered to be immune from re-infection, at least in the short to medium term after recovery, and hence do not need immunisation.

Test of Cure (TOC)

TOC is not necessary, as this is a self-limiting infection.

Test for re-infection

Re-testing for mpox is not necessary.

Special considerations

Offer HIV pre-exposure prophylaxis to anyone who has recovered from mpox, after conducting appropriate assessment. See PrEP Guidelines.