A VIRUS swept through Mid Cheshire Hospitals NHS Foundation Trust last week affecting 85 computers – three per cent of the Trust’s PCs.

One of the affected computers was at the Victoria Infirmary, in Northwich, while the others were at Leighton Hospital.

Annie Harvey, head of communications at the Trust, said patient and clinical information was secure.

“No core clinical systems were affected and therefore the virus has not impacted on patient care or appointments.

“As the virus did not affect clinical programmes, the issuing of blood test results to primary care colleagues was not affected,” she said The Conflicker virus was detected on January 20 and a Trust spokesperson confirmed that it had been cleared from all affected computers by Sunday, January 24.

It is policy that all of the Trust’s IT equipment has antivirus software installed and an intrusion prevention system to monitor all incoming and outgoing traffic.

The Trust is investigating how the PCs became infected – it is believed to have been caused by an external USB device.

Ms Harvey said the situation would continue to be monitored and all non-affected machines would be checked.

Conficker, also known as Downup, Downadup and Kido, is a computer worm targeting the Microsoft Windows operating system that was first detected in 2008.

It uses flaws in Windows software to co-opt machines and link them into a virtual computer that can be commanded remotely.

Conficker has since spread rapidly into what is now believed to be the largest computer worm infection since 2003 with more than seven million government, business and home computers in more than 200 countries now under its control.

Organisations affected in the past include Intramar, the French Navy computer network, forcing aircraft at several airbases to be grounded because their flight plans could not be downloaded.

In the UK, the worm has spread across administrative offices aboard Royal Navy warships and submarines An infection of Manchester City Council's IT system caused an estimated £1.5million worth of disruption in February 2009. Bosses have since banned the use of memory sticks and disabled USB drives.