Officials at a Texas jail are trying to figure out why two inmates died and two others were hospitalized with a mysterious illness within the past month.

The four men, three of whom were foreign nationals, were all apparently healthy when they arrived at the jail, The San Antonio Express-News said Friday.

The Val Verde Correctional Facility and County Jail is a privately operated 850-bed medium-security facility under contract to house federal detainees as well as local prisoners.

Dr. Sandra Guerra-Cantu, regional medical director of the Texas Department of State Health Services, said health officials were asking the U.S. Centers for Disease Control for assistance.

Symptoms began with erratic behavioral changes, followed by incontinence and dehydration, the newspaper said. Tests for medical conditions and toxic exposures failed to identify a cause of death.

The facility is operated under contract by the Geo Group Inc., a Boca Raton, Fla., company.

Copyright 2007 by United Press International