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
- Most infections are asymptomatic
- When symptomatic, incubation period 5-18d
- May get mild flu-like illness to acute or chronic pulm. infection
- Disseminated disease with fever, splenomegaly, diffuse pulm infiltrates
IV. Dx: serology (serum & urine; urine more sensitive), sputum cx, lung bx cx
V. Tx of disseminated histoplasmosis in AIDS
- Initial "induction" with Ampho B--highly effective
- Us. relapse 6-18mos post-induction without prophylaxis
- Maint. prophylaxis regimens after Ampho B induction:
- Ketoconazole 200-400mg/d: 36-50% relapse in small studies
- Ampho B 50-100mg IV Q1-2wk: 5-20% relapse rate
- Itraconazole 200mg PO BID (with meals)
- 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)
- Unknown effectiveness of Itra in preventing recurrence of CNS histo
- Fluconazole has few side-f/x & is effective against histo in humans, but more experience w/itraconazole for histo