| Cohort | The Coccidioides isolates used in the study were obtained from human patients. All Coccidioides isolates were grown under biosafety level 3 (BSL-3) containment, under conditions that induce mycelial or spherule growth. Fungal growth conditions were performed as described previously (18, 43) and are summarized here in brief. For mycelial growth, a 50-ml vented falcon tube containing 10 ml of RPMI medium ( lter sterilized RPMI 1640, 10% fetal bovine serum) was inoculated with a 1-cm by 1-cm 2 glucose yeast extract (GYE) agar plug for each strain. These plates were inoculated using 100ml of a glycerol stock, spread across the plate, and cultured at 30°C for 2 weeks. Control RPMI medium was inoculated with a plug from sterile 2 GYE agar medium. |
| Disease Introduction Mechanism | Coccidioidomycosis, or Valley fever, is a disease that is endemic to the deserts of the western United States, Mexico, and Central and South America and is responsible for an estimated 350,000 new infections per year. In highly populated areas of the United States where the disease is endemic, e.g., Phoenix and Tucson, AZ, and the San Joaquin Valley in California, up to 30% of community-acquired pneumonias may be caused by Valley fever, and with growing populations in these regions, Valley fever cases in the United States are expected to climb. The causative agent of Valley fever is the opportunistic pathogen Coccidioides, a genus of dimorphic fungi comprised of two species, Coccidioides immitis and C. posadasii. In the environment, Coccidioides spp. grow in the soil during rainy periods as saprobic mycelia, which become dormant and form arthroconidia during dry periods. As the soil is disturbed, the arthroconidia can become airborne, and when inhaled, the fungus can initiate a parasitic life cycle as spherules within the lungs of a susceptible host, causing pneumonia. The median duration of human Valley fever pneumonia is 120 days, costing over $93,000 per person in direct and indirect costs. Approximately three-quarters of the diagnosed cases of Valley fever require antifungal therapy, and 1% of those infected will experience disseminated disease, with one-third of those being fatal. |
