Monkeypox virus

Associated infections

• Mpox (monkeypox)
• Secondary bacterial infection of skin lesions
• Proctitis and mucosal lesions
• Ocular mpox and keratitis
• Severe or disseminated disease in immunocompromised individuals

Transmission route

Transmission occurs predominantly through close physical contact with an infectious person, including skin-to-skin and mucosal contact, kissing, and prolonged face-to-face proximity that may generate infectious respiratory particles. Lesion material carries the highest viral burden, and direct contact with lesions or lesion crusts is the dominant mechanism. Sexual contact has been the dominant amplifier of transmission in recent global outbreaks, reflecting the combination of prolonged skin-to-skin contact and mucosal exposure rather than any property unique to sexual transmission itself. Household transmission occurs but at lower rates, consistent with the requirement for sustained close contact.

Contact with contaminated clothing, bed linen, towels or other fomites is a recognised route. Orthopoxviruses are relatively robust on dry surfaces compared with many enveloped viruses, and viable virus has been recovered from the environment around cases, particularly from textiles and from surfaces in close proximity to lesions. Handling of contaminated linen in a manner that generates dust or agitation is a recognised occupational risk, which is why linen from a known case is handled with minimal agitation and treated as infectious. Needlestick injuries in healthcare and tattooing settings have transmitted infection, as have other percutaneous exposures to lesion material.

Zoonotic acquisition occurs through bites, scratches or handling of infected animals during hunting, skinning or food preparation, and remains the mechanism by which the virus is introduced into human populations in endemic regions. Vertical transmission from a pregnant person to the fetus or newborn has been described and may result in fetal loss or congenital infection. Transmission has not been demonstrated through drinking water, treated water systems or wastewater exposure, and while orthopoxvirus DNA can be detected in wastewater and has been used for community surveillance, the detection of DNA does not indicate the presence of infectious virus or a waterborne transmission route.

Relevance in endoscopy and reprocessing

The principal control for mpox in endoscopy, CSD and dental services is recognition and deferral. A patient with an unexplained rash, anogenital or oral lesions, or fever with lymphadenopathy and a relevant epidemiological history should not proceed to an elective procedure until the diagnosis is resolved; the case should be discussed with infectious diseases and notified to the relevant public health authority. Dental services warrant particular attention, since oral and perioral lesions may be the presenting feature and the dental chair may be the first clinical contact. Where a procedure is urgent and cannot be deferred, it should proceed with transmission-based precautions in place rather than being performed unrecognised.

Contact and droplet precautions apply, with airborne precautions added for aerosol-generating procedures. Personal protective equipment should comprise a fluid-resistant gown, gloves, eye protection and a particulate respirator, with attention to complete coverage of exposed skin given that direct contact with lesion material is the dominant transmission route. Endoscopy, particularly upper gastrointestinal and bronchoscopic procedures, and most dental procedures using high-speed handpieces or ultrasonic scalers, are aerosol-generating and should be undertaken in a room with appropriate ventilation, with the minimum necessary staff present, and with a defined post-procedure interval before the room is cleaned and reoccupied. Single-use items should be preferred where a clinically equivalent option exists. Staff with potential occupational exposure should be assessed for post-exposure vaccination, which is effective when administered promptly, and placed under symptom monitoring.

Device handling follows the reprocessing-failure and quarantine principles applied to other high-consequence pathogens. Instruments used on a patient with suspected or confirmed mpox should be contained at the point of use, transported in a rigid sealed labelled container, and reprocessed according to AS 5369:2023 and the manufacturer's instructions for use; where a reprocessing failure is identified or suspected, the device should be quarantined pending review by infection prevention and the sterilising services manager rather than returned to circulation. Enveloped viruses including orthopoxviruses are susceptible to the cleaning and high-level disinfection processes already validated for these devices, so the requirement is that the standard process be performed in full rather than that a different process be substituted. Environmental cleaning should address all surfaces contacted by the patient using an agent with demonstrated activity against enveloped viruses, linen should be handled with minimal agitation and bagged at the point of use, and clinical waste managed under the applicable jurisdictional requirements.

Interpreting a detection

Monkeypox virus is not a rinse-water surveillance target. The water quality parameters applied to endoscopy, CSD and dental facilities under AS/NZS 5369 are directed at organisms that colonise water systems and can recontaminate a device at the final rinse, principally Pseudomonas aeruginosa and other Gram-negative water organisms, non-tuberculous mycobacteria and Legionella species, together with total viable count, conductivity and endotoxin as indicators of system performance. Orthopoxviruses cannot replicate in water, are not enumerated by any routine water testing method, and are not included in any validated environmental panel for healthcare water. Their relative durability on dry surfaces does not translate into water-system relevance, and it should not be used to justify adding them to a water monitoring programme.

Where orthopoxvirus or monkeypox virus DNA is reported on a water or rinse-water sample, the result should be regarded as a probable artefact. Poxvirus polymerase chain reaction assays are performed in laboratories that also handle lesion swabs carrying extremely high viral loads, together with positive control material and, in some laboratories, vaccinia-based reagents. Specimen carryover during extraction and pipetting, and amplicon contamination of reagents, consumables and work surfaces, are recognised failure modes in that setting and are far more probable explanations than genuine contamination of a treated water loop. Detection of DNA does not demonstrate the presence of infectious virus, and there is no mechanism by which the virus could reach or be sustained in a water system.

The resolution pathway runs through the laboratory rather than the water system. Confirm sample identity and matrix first: check the chain of custody, sample point identifier, collection date, container type and labelling, and confirm that water rather than a misrouted clinical specimen was tested. Then establish whether the assay was validated for environmental matrices, since these assays are validated on lesion swab material and their extraction efficiency and inhibition behaviour on a low-biomass water matrix are undefined; review the extraction blank and no-template control, and check whether the sample was run adjacent to a high-titre clinical specimen or a control. Resample the same point with fresh, unopened consumables and a separate sampling kit, splitting the resample between laboratories where practicable. Escalate to laboratory quality management, which owns contamination control and workflow segregation, and record the event as a laboratory quality issue rather than a water quality exceedance. The water safety group should be notified for awareness but should not initiate flushing, disinfection, filter replacement or system shutdown on the basis of the result, and the finding should not be trended against the facility's rinse-water data. Separately and independently, infection prevention should confirm whether any patient or staff member with compatible lesions and epidemiological risk has been managed at the facility; if so, that thread is pursued through contact tracing, exposure assessment and public health notification, not through water quality management.