Health officials in Washington State have issued a warning of a virus outbreak on the Microsoft campus at Redmond, but it's the creation of nature rather than a hacker.

The alert is for a case of measles that was picked up by an employee while overseas and which the authorities are keen to stop from spreading. The US has about 350 cases of measles reported each year.

“We live in a global village where infectious diseases can spread rapidly from distant parts of the globe to our doorstep in a matter of hours,” said Dorothy Teeter, interim director and health officer for public health for Seattle and King County.

“This instance shows why immunisations are critically important in protecting the health of our community.”

The advisory is also revealing in what it says about the habits of Microsoft employees. The virus has been identified in just four spots: Microsoft campus, its cafeteria and the Malay Satay Hut and Thai Ginger restaurants.