Monkeypox Virus - Credit CDC PHIL
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While the public often dismisses mpox as a `niche' or `lifestyle' disease - and unlikely to affect them - it is a cousin to the smallpox virus which (during the 20th century alone) killed hundreds of millions of people (cite).
Last January, the CDC published a review called The Rise of Mpox in a Post-Smallpox World, which characterized the virus as having `pandemic potential' no less than 4 times.
Reports of mpox are rising in Africa where the disease is endemic and in new countries where the disease has not been previously seen. The 2022 global outbreak of clade II mpox and an ongoing outbreak of the more lethal clade I mpox highlight the pandemic potential for monkeypox virus.
Waning population immunity after the cessation of routine immunization for smallpox plays a key role in the changing epidemiologic patterns of mpox. Sustained human-to-human transmission of mpox is occurring widely in the context of insufficient population immunity, fueling genetic mutations that affect the accuracy of some diagnostic tests and that could lead to changing virulence.
We've been following the evolution and spread of mpox (formerly Monkeypox) in this blog for more than 15 years, including studies warning of its increasing threat.
We now have at least 4 clades of Mpox in circulation (I, Ib, II, IIb), with Clade Ia and Ib considered the most severe. Two clades (IIb and Ib) have managed to spread internationally, and the WHO's most recent risk assessment puts their global risk as Moderate to High.
Although the vast majority of Mpox cases outside of Africa have occurred among men who reported recent male-to-male sexual contact (MMSC), a small - but notable - number of cases reported no such activity.
A 2023 MMWR report (Possible Exposures Among Mpox Patients Without Reported Male-to-Male Sexual Contact). suggested other possible routes - including fomites - might be a factor. Since 2022 we've seen several studies on extensive environmental contamination with the Mpox virus - both in household and hospital settings - including:
Admittedly, viral DNA may be detected, even when the virus is no longer viable or is in concentrations too low to be infectious. But in the EID Journal report above, researchers were able to isolated viable MPXV on household surfaces after at least 15 days, although low titers (<102 PFU) suggested a limited potential for indirect transmission.
All of which brings us to a new study published in Eurosurveillance, conducted by the UKHSA, on environmental contamination from Mpox clade Ib in a hospital setting. Viral DNA was detectable in > 70% of samples taken.
The results are similar to those reported (above) from clade IIb studies in 2022-2023.
Air and surface sampling for clade Ib monkeypox virus in United Kingdom hospitals, 2024 to 2025
Barry Atkinson1,2 , Susan Gould2,3,4 , Ian Nicholls1 , Khanzadi Nazneen Manzoor1 , Jack Smith1 , Andrew J. Hindle5 , Anne J. Tunbridge5 , Joby Cole5,6 , Paul Collini5,6 , Alejandra Alonso7 , Geraldine O’Hara8 , Cecilia Tuudah8 , Jonathan A. Otter8 , Berkin Hack8 , Caroline Taylor9 , Thomas Pottage1 , Tom Fletcher2,3,4 , Jake Dunning2,9,10
Between late October 2024 and the end of January 2025, the first eight patients with clinical symptoms of clade Ib monkeypox virus (MPXV) infection were identified in the United Kingdom (UK). Seven of them were admitted for clinical observation and monitoring to airborne high consequence infectious disease (HCID) centres. To understand if the immediate environment of patients with clade Ib mpox can become contaminated with MPXV, we investigated whether this virus could be detected in environmental surface and air samples collected from the seven patients’ rooms or anterooms.(SNIP)
Environmental sampling in isolation rooms
Environmental air and surface sampling was conducted as previously described [2]. Briefly, environmental sampling was performed on seven separate occasions in rooms occupied at the time by patients with confirmed clade Ib MPXV infection (five sampling events) or ca 16 hours post discharge of patients with confirmed clade Ib MPXV infection (two sampling events). One of these sampling events took place in a room occupied by two co-habiting infected individuals (Cases 2 and 3), and two separate sampling events were performed around the same individual 6 days apart (Case 5). The sampling scheme aimed to sample the same surfaces in all rooms and to collect air samples both before and during a bed linen change; however, minor variations were made to account for different room set-ups, such as the absence of a sink in one of the patient-rooms.
(SNIP)
MPXV DNA was detected in 66/90 surface samples collected (Table 2). Unsurprisingly, samples from frequently touched points often contained detectable MPXV DNA, with MPXV detected in bathroom tap handle samples collected during all seven sampling events. Similarly, the shower handle and toilet flush samples contained detectable MPXV DNA from six of seven sampling events.
(SNIP)
Discussion
The results from the currently reported investigations confirm that clade Ib mpox patients contaminate their immediate environment and that infection-competent virus may be present, which may pose a risk of onward transmission. While it is not possible to accurately quantify this risk using data from these investigations, they do support the need for defined infection prevention and control (IPC) measures when cases are detected to minimise the risk of exposure to viable virus in the environment that could present a transmission risk.
Findings from these environmental sampling investigations broadly align with those from studies performed in healthcare settings during the 2022 clade IIb public health emergency of international concern (PHEIC) [2,5-10]. Such information may contribute to the discussion regarding potential phenotypic differences between clade Ib and IIb MPXV; however, it is important to note the small sample size in both datasets.
Our investigations again demonstrate that MPXV can be detected in air samples collected when bed linen is changed; however, detection of MPXV in air samples was uncommon in this study (only one of seven bed linen-change samples contained detectable MPXV DNA), despite the inclusion of some patients with high lesion-counts.
We have a long history of underestimating or pigeonholing viruses, thinking that the way they behaved yesterday, and the day before, tells us how they will behave tomorrow and all the days, weeks, and years that follow.
It may be comforting, but that isn't how viruses - and evolution - work.
We've seen recent reports of household transmission' of mpox clade Ib (including to children) in the UK (see Eurosurveillance report), and in Germany and Belgium (see ECDC: Epidemiological Update).
Last month, the UK reported their first `community acquired' case of Mpox clade Ib; one with no travel history or link to a previously identified case. The numbers may be limited, but they serve as a proof of concept.
Making the better we understand the ways this virus can spread, the better our chances of containing it.
