SACRAMENTO (AP) — California will have to move more than 2,100 inmates from two Central Valley prisons because they could be susceptible to contracting a potentially deadly illness, officials said Thursday.

Test results showed that another 3,050 inmates have already been exposed to the soil-borne fungus that causes valley fever and could be moved to the prisons near Fresno.

The decision comes after nearly 37,000 inmates statewide were tested earlier this month for previous exposure to valley fever.

Once exposed, they are unlikely to get valley fever again, said Joyce Hayhoe, spokeswoman for the federal court-appointed receiver who controls prison medical care.

Valley fever often produces no symptoms, but causes mild to severe flu-like symptoms or more serious infections in about 40 percent of cases. It potentially can spread through the body, causing blindness, skin abscesses, lung failure and death.

The tests found that 1,350 inmates at Avenal State Prison and 815 Inmates at Pleasant Valley State Prison have not been exposed and so are in danger of contracting the infection.

“These persons must be moved out of these prisons,” Hayhoe said in an email.

The state Department of Corrections and Rehabilitation will work with the receiver’s office to move the inmates as quickly as possible, department spokeswoman Deborah Hoffman said.

The department previously had to transfer black, Filipino and medically risky inmates from the two prisons in 2013 because those groups are more susceptible to the fungal infection.

The state spent $5.4 million to buy enough of the $60 skin tests for about 90,000 inmates. However, nearly 60,000 inmates refused to be tested.

The remaining unused tests will be saved and used in the future, Hayhoe said.