Coccidioides spp. (Cocci) is the fungal species that causes Valley Fever (coccidioidomycosis). It is located primarily in the desert soils of Southwest Arizona (see image below) and Central Valley California where the disease got its namesake.
Cocci transforms from a mycelia structure to fungal spores (arthroconidium) in the soil near the ground surface. The spores are 3-5 microns in size (1 micron = 0.000039 inches).
The fungal spores become airborne when the desert soil is disturbed, e.g. strong wind (see dust devil photo below) or even gentler wind.
Once airborne, the fungal spores can be inhaled by humans or other animals and infect the lungs.
Once deep in the lungs, the spore changes form and becomes a spherule (infection). The spherules can grow up to 75 microns and eventually burst releasing endospores---each of which becomes another spherule (see image below). This process will continue until the body's immune system controls the infection. If the immune system cannot control the infection, then treatment will be required.
Lung nodules can form around the spherules. In most cases they do not cause a problem but can be confused as lung cancer on CT Scans. Below is a CT Scan of my lungs taken when the symptoms were the worst on 10/23/20. There are many nodules and one was 2.5 centimeters in size. They will typically disappear within a couple of years.
Now that we know about the fungus and the infection, in Part III we will cover the Symptoms and Diagnosis.