California authorities are investigating a Valley fever outbreak that sickened 28 workers at solar power plants under construction in Central California.
Public health and work safety staff visited two sites in San Luis Obispo County two months ago, the Los Angeles Times reports.
Valley fever is contracted by breathing spores from a fungus found in desert soil. It can cause flu-like symptoms and death in extreme cases.
Mark Simonin of an electrical workers union says one infected worker was an electrician who inhaled dust while digging at one site.
California is trying to stem a Valley fever outbreak that has caused dozens of deaths among Central Valley prisoners since 2006. This week, federal officials ordered more than 3,000 inmates relocated.