Ebola virus

Associated infections

• Ebola disease (Ebola virus disease)
• Viral haemorrhagic fever
• Post-Ebola sequelae including uveitis and persistent arthralgia
• Occupationally acquired infection in healthcare workers

Transmission route

Human-to-human spread occurs through direct contact with blood, secretions, organs or other body fluids of a symptomatic or deceased person, and through contact with surfaces, linen and clothing freshly contaminated with those fluids. Virus enters through broken skin or through the mucous membranes of the eyes, nose and mouth. Viral load rises with clinical severity, so the most heavily infectious patients are those who are sickest and those who have died, which explains the concentration of transmission around late-stage care and around handling of the deceased. Traditional burial practices involving washing of and contact with the body have been a repeatedly documented amplifier of community transmission.

Healthcare workers have been infected repeatedly when standard and transmission-based precautions were not strictly applied. The recognised failure points are unprotected contact with vomitus, diarrhoeal fluid or blood during resuscitation and nursing care; sharps injury during phlebotomy or cannulation; and self-contamination during the removal of personal protective equipment. Transmission in healthcare has also been amplified historically by the reuse of needles and syringes and by inadequate instrument reprocessing in resource-limited settings. Because the earliest symptoms are non-specific and resemble malaria, typhoid and other febrile illnesses common in the same regions, initial presentations are frequently managed without precautions, and index healthcare transmission often precedes recognition of the outbreak.

Persistence of virus in immunologically privileged sites has been documented after clinical recovery. Viral RNA has been detected in semen, ocular fluid, cerebrospinal fluid and breast milk for extended periods following resolution of acute illness, and a small number of late sexual transmission events have been attributed to this persistence. This has led to survivor follow-up programmes offering semen testing, counselling and ophthalmological review. Airborne transmission between humans is not a recognised route, and there is no evidence of spread through intact skin, through casual contact with asymptomatic individuals, or through food or drinking water in the manner of enteric pathogens.

Relevance in endoscopy and reprocessing

The likelihood that an Australian endoscopy, CSD or dental facility encounters Ebola virus is very low, but the consequences of an unrecognised case are severe, which is why the organism is treated as a critical infection-control consideration rather than a routine one. The primary control is recognition at the point of booking or presentation: a patient with fever and a compatible illness who has travelled from, or had contact with a person from, an area with a current outbreak within the preceding 21 days should not proceed to an elective procedure. Such a patient should be isolated immediately, managed under the facility's viral haemorrhagic fever protocol, and referred to the designated receiving hospital, with the local public health unit notified without delay.

Where a procedure cannot be deferred, contact, droplet and airborne precautions apply together. Personal protective equipment should provide complete skin and mucous membrane coverage: a fluid-resistant gown or coverall, double gloves, a particulate respirator, and eye protection or a full face shield, with a trained observer supervising donning and doffing. Doffing is the highest-risk step and should follow a written sequence in a designated area. Endoscopy and dental procedures generate splash and aerosol, and gastrointestinal procedures involve direct contact with the body fluid compartment carrying the highest viral burden, so aerosol-generating procedures should be performed in the most controlled environment available, with the minimum number of staff present and with disposable items used in preference to reusable ones wherever a clinically equivalent option exists.

Devices used on a patient with suspected or confirmed Ebola disease should be quarantined immediately at the point of use rather than being returned to the normal reprocessing stream. Transport should be in a rigid, sealed, labelled container, and reprocessing decisions should be taken jointly by infection prevention, the sterilising services manager and the treating clinical team, in accordance with AS 5369:2023 and the device manufacturer's instructions for use. Where the manufacturer's validated process cannot be assured, or where the device cannot be cleaned to the standard required before disinfection, disposal is the appropriate outcome. Bulk body-fluid spills should be contained and decontaminated using a process validated for enveloped viruses, all waste should be handled as clinical waste under the applicable jurisdictional requirements, and every staff member with a potential exposure should be recorded and placed under 21-day symptom monitoring by occupational health.

Interpreting a detection

Ebola virus is not a rinse-water surveillance target. AS/NZS 5369 and the associated water quality requirements for endoscopy, CSD and dental facilities are directed at organisms with a genuine capacity to colonise water systems and to recontaminate reprocessed devices at the final rinse, principally Pseudomonas aeruginosa, other Gram-negative water organisms, non-tuberculous mycobacteria, Legionella species and the total viable count as a general indicator of system condition. Filoviruses have no such capacity, are not enumerated by any routine water testing method, and are not included in any validated environmental testing panel. There is no scenario in which routine water monitoring should be expected to generate a filovirus result.

If a laboratory nevertheless reports filovirus nucleic acid on a water or rinse-water sample, the overwhelmingly probable explanation is contamination of the sample or of the assay rather than contamination of the water system. Nucleic acid amplification detects fragments of genetic material irrespective of viability, and laboratories that also process clinical specimens, positive control material or synthetic template are exposed to specimen carryover and to amplicon contamination of reagents, pipettes and work surfaces. The plausibility of a genuine result should be weighed against the fact that the virus cannot replicate in water and would have no means of arriving at, or persisting in, a treated water loop.

The resolution pathway should be followed in order and should not begin with disruption of the water system. First, confirm sample identity and matrix: verify the chain of custody, the sample point identifier, the collection date and the labelling, and confirm that a water sample rather than a clinical specimen was received and tested. Second, confirm the assay: establish whether the method was validated for environmental matrices at all, and review the run controls, including the no-template control and any extraction blank. Third, resample from the same point using fresh, unopened consumables and a separate sampling kit, ideally with a second sample sent to an independent laboratory. Fourth, escalate to laboratory quality management rather than to the water safety group, since the fault to be investigated lies in specimen handling or assay control and not in the plumbing. The water safety group should be informed for completeness but should not initiate flushing, disinfection or system shutdown on the basis of such a result. In parallel, and independently of the water finding, infection prevention should confirm that no patient with a compatible illness and relevant travel or contact history has been managed at the facility; if one has, that clinical thread is investigated through the exposure and reprocessing-failure pathway and reported to the public health unit, not through water quality management.