Disseminated Histoplasmosis

  • Basic Information

    • 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.
  • Clinical Manifestations

    • Immunocompromised hosts can present with more severe symptoms: fevers, night sweats, nausea, vomiting, dyspnea.
    • 50% of AIDS patients with disseminated histoplasmosis have pulmonary involvement.
  • Diagnosis

    • 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.
  • Management

    • 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.