Monkeypox patients are likely to shed high viral loads that can be 'potentially' infectious, German scientists have found.

The team, including from University Medical Center Hamburg-Eppendorf (UKE) and Bernhard-Nocht Institute for Tropical Medicine (BNITM), analysed the hospital rooms of two monkeypox patients. They swabbed the surfaces of rooms, Including their bathrooms and the adjacent anterooms where workers would change in and out of personal protective equipment (PPE).

The findings, published in the journal Eurosurveillance, showed all surfaces directly touched by the patients' hands showed viral contamination with the highest loads detected in both bathrooms. The viral loads were highest in the patients' bathrooms, particularly on toilet seats or the control levers of their sink or soap dispenser.

The virus was also detected on the patients' chairs, the fabrics in their rooms (towels, shirts, pillowcases), and one patient's mobile phone. Some degree of viral DNA was also found "on all other investigated surfaces in the patients' rooms, although it was not known at the time of testing whether and to what extent the patients had also touched these surfaces, a researcher wrote in the paper.

In the anteroom, all hand-contact points examined yielded positive PCR results. Traces of viral DNA were identified on the handle of both anteroom doors located in the ward corridor, outside the anteroom.

The team noted that there is currently no "definite data" on what amount of viral load is needed to transmit monkeypox. This means that although monkeypox was found on several surfaces in the patients' rooms, infection would not necessarily occur from touching them, they claimed.

However, they also noted that contaminated surfaces have the "potential to be infectious", and "it cannot be ruled out that their contact with especially damaged skin or mucous membranes, could result in transmission."

The study's findings are "absolutely an expected development" and that "outside of very heavily contaminated areas surfaces in the community are not likely to be at high risk for transmission", said Hugh Adler, from the department of clinical sciences at the Liverpool School of Tropical Medicine. 

"Patients with extensive skin lesions admitted to hospital are likely to spread the highest amount of virus to the environment," he said. "Patients with the milder disease might shed less; we don't know yet."

"Monkeypox viral persistence on surfaces is already well known in public health circles, and current public health guidelines for people self-isolating at home include recommendations for how to do laundry and steps to be taken to prevent transmission to household contacts," Adler said.