California corrections officials said Tuesday they will comply with a federal court order to move thousands of inmates out of two Central Valley prisons where an airborne fungus has led to widespread illnesses.

The department does not know yet where it will put the 2,600 displaced inmates as it juggles the population within the state's 33 adult prisons, Department of Corrections and Rehabilitation spokeswoman Deborah Hoffman told The Associated Press.

Officials could seek an extension if they cannot completely comply within the 90-day deadline set last week by U.S. District Judge Thelton Henderson in San Francisco.

Officials had said they might appeal Henderson's order but then decided to comply.

The judge's order requires corrections officials to transfer most black, Filipino and medically at-risk inmates from Avenal and Pleasant Valley state prisons because they are more vulnerable to health problems from Valley fever, a fungal infection that is not contagious and originates in the soil of the San Joaquin Valley.

About half of the infections produce no symptoms, while most of the rest can bring mild to severe flu-like symptoms. In a few cases, the infection can spread from the lungs to the brain, bones, skin or eyes, causing blindness, skin abscesses, lung failure and occasionally death.

The two prisons, which house a combined 8,100 inmates, are about 10 miles apart and 175 miles southeast of San Francisco.

"Transferring thousands of inmates is an extremely complex process. It will take time," Hoffman said. "We must identify where to send individual inmates and which inmates from other facilities can be transferred into Avenal and Pleasant Valley."

Transferring less vulnerable inmates into the two prisons could create an additional problem if those inmates object.

"This is a hard question. We are concerned about the risk to other prisoners," said Don Specter, director of the nonprofit Prison Law Office and lead attorney in the lawsuit involving valley fever. "The question is, `How great is the risk?'"

He deferred to J. Clark Kelso, who was appointed by Henderson to oversee medical care within the state prison system.

Joyce Hayhoe, a spokeswoman for the federal receiver, said inmates who believe they may be vulnerable to the illness could challenge being moved into the two prisons if they can demonstrate that they fall into one of the excluded categories.

Inmates who previously had the infection are exempt from the judge's order because they can't get it again. Inmates who don't want to move from the two prisons can decline to be transferred.

The department has moved more than 560 inmates from the two prisons since January because they are considered to be medically at risk, Hoffman said. The department was in the process of moving another 240 at-risk inmates by August.

Now it will have to move far more inmates at the same time other transfers are underway.

The department is set to begin a six-month transfer of 1,700 seriously sick and mentally ill inmates into a nearly $840 million medical complex in Stockton. The California Correctional Health Care Facility is designed to accept patients who cannot be treated in the basic medical clinics at other prisons including Avenal and Pleasant Valley.

The department also is appealing a court order that will otherwise force the state to release 10,000 inmates by year's end to reduce prison crowding, a measure the federal courts have said is needed to improve inmates' health care.

Moreover, moving large groups of inmates based on their race creates its own dilemma because most prison gangs in California also are racially segregated.

"That can dramatically affect the safety and stability of prisons," Hoffman said. "We have to be careful about sparking racial and gang violence."

Henderson and attorneys representing inmates had criticized the department for not doing enough to protect inmates and employees from the potentially deadly Valley fever fungus, a problem that has been known for years.

The state previously said it was premature to move inmates until officials could gauge the effectiveness of other measures, including installing air filters, minimizing dust and screening out more dust from entering prison buildings. They also wanted to wait until the U.S. Centers for Disease Control can complete health studies at the prisons, a report that is not expected until December.

However, a preliminary report made public Tuesday from the affiliated National Institute for Occupational Safety and Health offered 16 practical recommendations, such as keeping doors and windows closed and sealing gaps in exterior walls, windows and doors.

In one case, inspectors found that employees at a clinical treatment center at Pleasant Valley State Prison had been propping open an exterior door with a rock, letting in unfiltered air.