Monkeypox patients can shed the virus into the surrounding environment, particularly from skin particles and in debris from skin lesions and scabs, a new study has found.
As the virus is relatively hardy, it can also remain infectious on surfaces for weeks, creating a potential infection risk to others.
Although the UK Health Security Agency (UKHSA) recommends hospitalised monkeypox patients who have severe disease are cared for in isolation rooms, with infection prevention and control (IPC) precautions, it is unclear if these measures are proportionate to the potential virus exposure risks.
Researchers from the Liverpool School of Tropical Medicine, the University of Oxford’s Nuffield Department of Medicine and the UKHSA have conducted a study into it and their findings are published in *The Lancet Microbe*.
They assessed the extent of virus shedding onto surfaces in specialist isolation rooms, where patients with severe monkeypox were being treated, and investigated if the virus was detectable in air samples from the rooms.
They found the viral DNA shed by the patients was on multiple surfaces throughout the isolation rooms, with 56 (93%) positive by PCR out of 60 samples.
Monkeypox virus DNA was also found on healthcare workers’ personal protective equipment (PPE) and in the anterooms where they remove their PPE, and it was also detected in five out of 20 air samples taken within these isolation rooms.
Changing bed linen was particularly associated with monkeypox virus DNA being detected in air samples in the room, which suggests viral particles, probably in shed skin particles, can become suspended in the air when bed sheets are changed.
Monkeypox virus capable of replicating in cells under laboratory conditions was identified in two of four PCR-positive samples selected for virus isolation, including air samples collected during the bed linen change.
Lead author, Dr Susan Gould, from the Liverpool School of Tropical Medicine, said: "Our results found that changing a patient’s bedding appears to be particularly associated with an increased ability to detect monkeypox virus in air samples.
"In 2018, a UK healthcare worker was thought to have developed monkeypox after being exposed to the virus while changing a patient’s bedding, before monkeypox had been considered and diagnosed.
"Our results suggest that changing bed linen used by hospitalised patients with monkeypox does indeed increase the risk of exposure to virus, by disturbing virus on bed linen and allowing it to be suspended in the air."�
The research team was also able to isolate replication-competent virus in some surface and air samples, which showed, for the first time, that monkeypox virus in some air samples taken around patients hospitalised with monkeypox is capable of replicating in cells and is not just ‘dead’ virus.
Senior author Dr Jake Dunning, of the University of Oxford’s Nuffield Department of Medicine and the Royal Free London NHS Foundation Trust, said: "It is important to note that detection of virus, even when demonstrated to be infectious, does not necessarily mean that exposure to the virus in real life would result in infection of the exposed person.
"However, it does reveal a potential transmission risk and one that is reasonable to control in hospital settings. Our results confirm that the strict IPC measures we follow in specialist infectious diseases centres are necessary and appropriate."�
The authors stress the investigation specifically evaluated exposure risks for patients in specialist facilities in hospitals and the results and recommendations may not apply to other settings, such as outpatient clinics. There is no suggestion that transmission of monkeypox virus via aerosols is a common way for the infection to spread from one person to another.
Dr Gould said: "In the context of ward-based care, our results support infection prevention and control measures designed to protect against exposure to infectious virus on surfaces and in the air, such as appropriate PPE, as well as applying measures designed to contain shed virus within hospitalised patients’ isolation rooms, including the use of negative pressure rooms and doffing areas."�
Gould S, Atkinson B, Onianwa O et al. Air and surface sampling for monkeypox virus in a UK hospital: an observational study. *Lancet Microbe* 7 October 2022
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