Barts Health Trust is battling a backlog of pathology tests after a computer virus disrupted the trust’s IT services at three major London hospitals.

The virus struck on Friday and was initially thought to be a so called ransomware virus by trust IT staff but has now been identified as a Trojan malware virus which has not been seen before.

The trust said today that it had successfully quarantined the files and dealt with the virus, which caused document sharing across the trust to be switched off.

In response to the issues the trust was forced to shut down all non-urgent pathology services at the Royal London, St Bartholomew’s and Newham hospitals.

An internal message to staff said only urgent requests would be processed. Staff were unable to view test results on the trust’s systems but were able to access historical results.

HSJ understands Newham’s pathology services came back online on Sunday but the systems at the Royal London and St Bartholomew’s were still offline last night.

In a message to staff today, shared with HSJ, deputy chief executive Tim Peachey said: “The virus has been quarantined, and all our major clinical systems are up and running.

“No patient data was affected, there was no unauthorised access to medical records, and our anti-virus protection has now been updated to prevent any recurrence. I am pleased to say the computerised pathology results service is now back online and processing requests as normal – although it may take a day or so to deal with the backlog that built up during the short period we had to process requests manually.”

Mr Peachey added: “This incident was what computer experts call Trojan malware. This particular virus has never been seen before. Following our investigations, I can categorically state that it was not ransomware, although initially it appeared to have some similar characteristics. However, it did have the potential to do significant damage to computer network files, which was why we took the measures we did. In fact our anti-virus protection software is automatically updated several times each day, and our anti-virus engineers had a brand new patch in place to quarantine this virus by Friday night, so all the effort since then has been to recover our position so we can all work normally again.”

He said: “The episode is a salutary reminder to all of us of the risks of opening attachments or weblinks from unknown sources.”

A spokeswoman for the trust said it was not able to confirm the number of tests in the backlog but promised to do so when it was able.