Thousands of California prison inmates may be at risk for an airborne fungal infection, reports Reuters. J. Clark Kelso, federal receiver for California's prison health care, has ordered the state's Department of Corrections and Rehabilitation to stop sending prisoners to the Avenal and Pleasant Valley state prisons after dozens of inmates there died of valley fever between 2006 and 2011.

The lung disease, caused by inhaling fungal spores, can become airborne when activities like construction or farming disturb the soil, Reuters says.

Kelso has specifically asked California Department of Corrections to not move prisoners who are at high-risk for contracting the disease, including those who are diabetic, of African-American and Filipino ancestry, immune-compromised, and over the age of 55. His newest directive asks the state to stop housing prisoners who fit into these categories, but does not yet demand that such prisoners be moved out of these prisons, Reuters adds.

The order will affect nearly 40 percent of the 8,200 prisoners housed at Avenal and Pleasant Valley, Kelso's spokeswoman Joyce Hayhoe told the Associated Press (AP).The state's efforts to mitigate the risks for its prisoners and prevent more deaths have been ineffective, she added.

Instead of moving prisoners, the corrections department has focused on ways to stop the spread of valley fever, including controlling the spread of dust during construction, and giving inmates surgical masks, said the AP.

The receiver's office said that the measures clearly aren't working, necessitating a stronger order from the receiver.