Commentary from Warren King of The Olympian. Full story

A significant spike in norovirus infections – what people often call the “stomach flu” – apparently has hit King County in recent weeks, including a fourfold increase in nursing-home outbreaks over this time last year.

Norovirus infections, which are not related to real influenza, always increase in winter. But the larger increase here is part of a national trend that federal health officials think may stem from a new strain of the virus that is widespread in Europe.

“It certainly seems to be a worse season than last year,” said Dr. Jeff Duchin, director of communicable-disease control for Public Health – Seattle & King County.

Outbreaks of the highly contagious bug were reported in 18 long-term care facilities in King County during December, compared with four during December 2005.

State law requires that norovirus outbreaks be reported to health officials only if they occur in health-care facilities, schools or long-term-care facilities. But the increase in nursing homes is an indicator of a general increase in the county, Duchin said.

State health officials said they aren’t certain if the illness has increased statewide.