- Coccidioidomycosis is caused by a fungus that grows in the southwest United States and parts of Mexico and South America. This disease is caused by breathing dust containing the fungus. It can lead to serious lung and breathing problems. Rarely, the fungus can infect other body parts. This is called disseminated coccidioidomycosis (DCM). If the fungus stays in the lungs for more than 6 months, it is called refractory coccidioidomycosis (RCM). People with DCM or RCM may have difficulty fighting off infection because of immune system problems. Researchers want to study the immune systems of people with DCM or RCM, to learn more about the disease and the best ways to treat it. They also want to learn more about the types of people that get DCM or RCM and about the fungus that causes it.