SACRAMENTO, CA – More than 1,100 inmates in eight separate state prisons have contracted a contagious illness that has made 10 employees sick and led to lockdowns, according to prison officials.

The illness, a bacterial disease called campylobacteriosis, was first reported at Deuel Vocational Institution in Tracy (San Joaquin County) on May 16, said Terry Thornton, a spokeswoman for the California Department of Corrections and Rehabilitation. Nearly 400 inmates got sick there, and the illness spread to other prisons in Northern and Central California, including the two women's prisons in the Central Valley, Folsom State Prison outside Sacramento and Mule Creek Prison in Ione (Amador County).

The bacteria cause fever, headaches, diarrhea, cramping and vomiting, and has sent a handful of inmates to the hospital, according to Thornton. The rest have been isolated in cells and treated. Thornton said prison officials were working with county public health officials to try to determine the cause of the illness and why it spread.

"It's a big mystery,'' she said.

Deuel Vocational Institution has reported no new ill inmates since Friday, and officials believe the worst of the outbreak may be over, Thornton said.