This patient's clinical presentation and biopsy showing spherules containing endospores is consistent with Coccidioides immitis infection, which is endemic in the southwestern US.
Coccidioides immitis is one of the 4 "systemic" mycoses along with Histoplasma capsulatum, Blastomyces dermatitidis, and Paracoccidioides brasiliensis. All 4 cause a mild pneumonia in immunocompetent patients and can cause disseminated disease in the immunocompromised. As seen on biopsy, Coccidioides is a spherule in tissue, differentiating it from the other systemic mycoses, which assume a yeast form in tissue. Coccidioides is most commonly found in the southwestern U.S., including Arizona.
Bayer reviews the diagnosis of Coccidiomycosis. They report primary pulmonary coccidioidomycosis is usually a self-limited disease characterized by fever, nonproductive cough and chest pain. Persistence of symptoms beyond eight weeks, continuously positive sputum cultures or negative skin tests with high serum complement-fixation titers for coccidiodomycosis suggest local progression or hematogenous spread. These situations are indications for antifungal therapy.
Hector et al. discuss the public health impact of coccidioidomycosis in Arizona and California. There was an increase in incidence of over 90% in the 2 states in the early 2000s, with blacks and Hispanics at particularly increased risk. They report lack of early diagnosis continues to be a problem, particularly when physicians suspect community-acquired pneumonia, underscoring the need for more rapid and sensitive tests.
Figure A shows a spherule containing endospores, the classic histologic appearance of Coccidioides.
Illustration A shows histologic examples of the systemic mycoses discussed in the second paragraph.
Illustration B shows the geographic distribution of regions where Coccidioides is endemic.
Answer 1: Lyme disease, a tick-borne illness that presents with the classic target-shaped erythema migrans rash as well as fever and arthritis, is endemic to the Northeastern United States.
Answer 2: Naegleria fowleri is a protist caught from immersion in freshwater (often swimming in Southeastern states such as Louisiana and Texas) that can cause CNS infection and death.
Answer 4: Histoplasma capsulatum is another systemic mycosis endemic to Ohio and the Mississippi River Valley. It is commonly found in bird and bat droppings.
Answer 5: Cryptococcus is another systemic mycosis that can cause pneumonia and is commonly found in soil contaminated with pigeon droppings.
Bayer AS. Recognizing coccidioidomycosis. Am Fam Physician. 1980 Sep;22(3):133-41.
PMID:7415923 (Link to Abstract)
Hector RF, Rutherford GW, Tsang CA, Erhart LM, McCotter O, Anderson SM, Komatsu K, Tabnak F, Vugia DJ, Yang Y, Galgiani JN. The public health impact of coccidioidomycosis in Arizona and California. Int J Environ Res Public Health. 2011 Apr;8(4):1150-73. Epub 2011 Apr 15. Review.
PMID:21695034 (Link to Abstract)