A Rare Case of Simultaneous Histoplasmosis and Coccidioidomycosis

Histoplasma and Coccidioides are fungi that can cause serious infections in immunocompromised patients. Histoplasma is primarily endemic to the central and eastern United States, while Coccidioides is primarily endemic to the southwestern United States. Here, we present a case of simultaneous histoplasmosis and coccidioidomycosis. A 69-year-old female with a past medical history of rheumatoid arthritis and polymyalgia rheumatica on immunosuppression presented to the emergency department (ED) with fevers, malaise, and confusion. She initially developed these symptoms a month prior while visiting her son in Tennessee. During this time, she lived in his basement where mold exposure was confirmed. Her symptoms gradually improved but recurred, prompting her to come to the ED. In the ED, her vital signs were as follows: temperature of 36.5˚C, heart rate of 88, respiratory rate of 16, blood pressure of 158/88, and oxygen saturation of 94% on room air. She was alert and oriented without focal neurologic deficits. Heart sounds were regular rate and rhythm, lungs were clear to auscultation bilaterally and abdomen was soft, non-tender, and non-distended. No skin rashes were observed either. Laboratory work revealed an elevated C-reactive protein (CRP), thrombocytopenia, and transaminitis. Chest X-ray showed patchy airspace disease in the left lower lobe, and she underwent a lumbar puncture which was negative for meningitis. Due to her travel to Tennessee, a urine Histoplasma antigen test was ordered which resulted positive, along with a beta-1,3-D-glucan level >500 picograms per milliliter (pg/mL), indicating disseminated histoplasmosis. Coccidioides antibodies also resulted positive, pointing to concurrent coccidioidomycosis. The patient was subsequently started on intravenous amphotericin B. Over the following days, the patient's transaminitis and thrombocytopenia improved, and she was ultimately discharged on oral itraconazole with outpatient infectious disease follow-up. Although the patient's exposure to mold was likely the source of her histoplasmosis, the source of her coccidioidomycosis is less clear given its endemicity. Even rarer is the coinciding infections, and to the best of our knowledge, this is one of the very few known cases. Immunocompromised patients who present with infectious symptoms should have a low threshold for a fungal infection workup, as prompt treatment is crucial to limiting the morbidity and mortality of these infections. Furthermore, geographic location should not narrow one's workup to endemic fungi only, as evidenced by this patient's simultaneous infections.