Officials turned off the water at San Quentin State Prison on Friday and temporarily trucked in portable toilets after an inmate was hospitalized with Legionnaires' disease and more than two dozen other prisoners showed signs of the illness.
The state corrections department, in conjunction with medical and health department staff, then began a hunt for the source of the bacterial infection, which can cause severe and sometimes fatal pneumonia.
"Fortunately, Legionnaires' is not an infectious disease — it cannot be transmitted person to person," said Joyce Hayhoe, a spokeswoman for the medical receiver's office that runs prison healthcare services in California. "It is transmitted through aerosolized water [such as steam], or inhaling contaminated soil."
State corrections spokeswoman Dana Simas said some 30 inmates at the Marin County prison — the state's oldest — were under observation Friday with for pneumonia-like symptoms.
One inmate who tested positive for the bacteria on Thursday remained hospitalized on Friday in stable condition, Simas said. Two others also were hospitalized but had not been officially diagnosed with Legionnaires' disease.
No staff members were reported sick with the bacteria.
In the meantime, prison officials ordered a halt to visitation and shut off water to the more than 3,700 inmates and 1,800 workers at the 163-year-old lockup. They brought in water trucks, bottled water and 100 portable toilets.
On the advice of public health experts, the prison decided by late Friday afternoon to allow inmates to again use the toilets in their cells, and to permit cooking with tap water.
"We have contingency plans for all types of emergencies, so it is something we were able to accomplish in just a few hours," said San Quentin spokesman Lt. Sam Robinson.
A recent Legionnaires' disease outbreak in New York City killed 12 people and sickened more than 100 others.
The source of that outbreak was traced to a rooftop air-conditioning unit at a historic hotel in the Bronx.
California public health records show 348 reported cases of Legionnaires' disease in 2014, two-thirds of them affecting individuals 65 or older. More than half of the cases occurred in Los Angeles County.
The U.S. Centers for Disease Control and Prevention estimates that fewer than half the cases of legionellosis, the proper medical term for the disease, are reported.
From 2009 to 2012, California reported 82 deaths attributed to the bacteria, according to the state Department of Public Health.