Each of the following statements concerning Coccidioides immitis is correct EXCEPT:

  •  In the body, spherules containing endospores are formed.
  •  The mycelial phase of the organism grows primarily in the soil, which is its natural habitat.
  •   Most infections are symptomatic and require treatment with amphotericin B.
  •  A rising titer of complement-fixing antibody indicates disseminated disease.