Valley Fever is a disease caught by inhaling the microscopic spores of a soil-dwelling fungus known as cocci, a fungus found buried in the desert of the Southwest from California to Texas.

Over the past 10 years, Valley Fever has increased 10-fold and an estimated 150,000 people are affected by it every year. According to infectious disease specialists, that's equal to the impact of Polio or Chicken Pox before vaccines were discovered, but there's no vaccine for Valley Fever.

Most people who show symptoms feel like they have a bad case of the flu, but for a small minority, it can be fatal. No one seems to know why it sickens some and kills others. 

The New Yorker's Dana Goodyear has been researching Valley Fever. She joins the show with more.