AIDS defining illness and typically seen in HIV patients with CD4<100 cells/microL.
The fungus (Histoplasma capsulatum) is found in soil contaminated with bird or bat excreta and transmission occurs from inhalation of spores.
Thought to be endemic in Ohio, Mississippi, Caribbean, Mexico, Asia, and Central/South America.
Immunocompromised hosts can present with more severe symptoms: fevers, night sweats, nausea, vomiting, dyspnea.
50% of AIDS patients with disseminated histoplasmosis have pulmonary involvement.
Elevated LFT’s, LDH, and ferritin are commonly seen. Elevated creatinine is considered a poor prognostic factor.
Although the initial chest x-ray often looks normal, may see diffuse interstitialor reticulonodular infiltrates.
Most sensitive and specific test for suspected disseminated histoplasmosis in an HIV patient is histoplasmosis antigen detection.
Histoplasmosis antigen can be detected in fluids including urine, serum, cerebrospinal fluid.
Rapid initiation of treatment is important and includes induction and maintenance phases. Amphotericin B is typically used for induction for 1-2 weeks. Therapy is then switched to itraconazole for consolidation and long-term suppression.
2009 IDSA guidelines recommend primary prophylaxis with itraconazole for HIV patients with CD4<150.