Recent investigations have revealed severe environmental MPXV contamination of patient rooms. This finding brings forth questions about the risk of transmission associated with people completing these activities. In a recent study, researchers were able to detect MPXV DNA in 66 of the 90 surface samples collected, about 73% of the surfaces tested. The study concluded that live virus was detectable in 19% of contaminated surfaces that underwent viral isolation.
We implemented a voluntary sampling program for staff following release of exposed patients. This program emphasized assessing surfaces and air quality within their rooms. MPXV DNA levels were almost an order of magnitude increased among cases with moderate to severe infections. This finding underscores a direct relationship between the severity of the clinical condition and environmental exposure.
Environmental Contamination Findings
The study reported that MPXV clade 1b DNA was found in 73% of surface samples taken from the infected patients’ rooms. On the other hand, 7% of air samples were positive for the virus. Most importantly, swabs taken from high touch surfaces, like bathroom tap handles, tested positive in all seven samples taken. This case demonstrates the risk of indirect transmission through contaminated surfaces.
Among the four samples that contained infectious virus, researchers identified contamination on a light switch from Case 1’s isolation room, a tap handle from Case 5’s ensuite bathroom, the anteroom exit for Case 5, and a window ledge in Case 8’s room. The recent findings illustrate the need for comprehensive cleaning practices in all areas of healthcare facilities to help reduce the risk for transmission.
“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,” – researchers
Variability in Viral Levels
In their study, the researchers tracked how viral levels varied in different cases over time. Cases 1, 5, and 8 were among the highest levels of MPXV DNA and were consistent with moderate to severe clinical presentations. Case 6 showed a moderate clinical severity. The significant Cq values shown were a result of low viral levels or absence of detectable MPXV DNA.
The researchers noted that this difference could be due to the cleaning of Case 6’s room just 12 hours before sampling was done. In comparison, the remaining rooms had been cleaned at least 24 hours before sample collection. This discrepancy in cleaning frequency may have affected the amount of detectable virus remaining in the environment.
“Interestingly, samples collected around Case 6 showed high Cq values or had no MPXV DNA detected despite this individual having ‘moderate’ clinical severity. This may be explained by this room being cleaned 12 hours prior to sampling as opposed to 24 hours for the remaining cases,” – researchers
Implications for Infection Control Measures
The unexpected high incidence of this study highlights the importance of strict IPC measures. These precautions are especially important in clinical or healthcare settings where Mpox cases are identified. A large fraction of commonly touched surfaces are contaminated enough to act as fomites that can transmit infectious viruses. That’s why it’s imperative to institute strong cleaning protocols and oversight right away.
“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 measures when cases are detected to minimize the risk of exposure to viable virus in the environment that could present a transmission risk,” – researchers
Our investigation found that all three of the female cases we reviewed contracted mpox through household transmission. This finding further highlights the importance of domestic environments in facilitating viral transmission. In total, four of these patients journeyed to areas outside of the UK where clade 1b MPXV is endemic. Three patients acquired the virus from infected family members here in the UK.
