I. Fungal infection cause by Histoplasma capsulatum

II. Endemic in Mississippi & Ohio river valeys

III. Infection occurs through inhalation of spores; particularly associated with exposure to bat or bird guano

IV. Clinical

  1. Most infections are asymptomatic
  2. When symptomatic, incubation period 5-18d
  3. May get mild flu-like illness to acute or chronic pulm. infection
  4. Disseminated disease with fever, splenomegaly, diffuse pulm infiltrates

IV. Dx: serologic tests for antigen (serum & urine; urine more sensitive), sputum cx, lung bx cx

V. Tx of disseminated histoplasmosis in AIDS

  1. Initial "induction" with Ampho B--highly effective
  2. Us. relapse 6-18mos post-induction without prophylaxis
  3. Maint. prophylaxis regimens after Ampho B induction:
  1. Ketoconazole 200-400mg/d: 36-50% relapse in small studies
  2. Ampho B 50-100mg IV Q1-2wk: 5-20% relapse rate
  3. Itraconazole 200mg PO BID (with meals)
  1. In an open-label uncontrolled trial in 42adult pts, mean age 34, 95% men, median CD4 ct 47M/l showed Successful suppression of histo in 39/42 pts; 2 relapsed on Itra; 1 had to d/c b/c of hypokalemia. No esoph/dissem. candida, or other systemic fungi during tx; yes cases of oral thrush (Ann. Int. Med 118:610, 4/93)
  2. Unknown effectiveness of Itra in preventing recurrence of CNS histo
  1. Fluconazole has few side-f/x & is effective against histo in humans, but more experience w/itraconazole for histo