Valley fever is a lung infection, and the medical name for it is Coccidioidomycosis or Cocci. It is caused due to a soil-dwelling, yeast-like fungus called "Coccidioides immitis". The disease is normally found in Southwestern US, parts of Central and South America, and Mexico. Valley fever is caused by a fungus that produces spores, which become airborne when the soil is disturbed by construction, natural disasters, wind, or agricultural activities.