Officials with Contra Costa Health Services were called to the Martinez Detention Facility in late January after sheriff's officers spotted a suspected case of chicken pox.
Sheriff's office spokesman Jimmy Lee said the first case was confirmed Jan. 21, and two other cases were identified within a few days. Lee said they are uncertain as to where the outbreak originated.
"It may be difficult to track down. The belief from Health Services is that someone brought it in from the outside," he explained.
Once the cases were identified, the detention facility initiated its infectious disease control plan. The plan includes segregating infected prisoners away from the general population, daily symptom screens to look for more cases, and the wearing of masks to limit the transmission of the virus.
Chicken pox is generally considered a childhood disease; less than 5 percent of the adult population is at risk of getting the virus due to lack of immunization or no previous contact with it. In adults, the virus can be more serious and can lead to further medical complications if not treated.
Information on chicken pox has been posted throughout the detention center, and corrections officers are on the lookout for any further cases.