From the Guidelines
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum, primarily acquired by inhaling fungal spores from soil contaminated with bird or bat droppings, and treatment is necessary for severe or disseminated disease, with liposomal amphotericin B 3-5 mg/kg daily for 1-2 weeks, followed by itraconazole 200 mg twice daily for at least 12 months being the recommended treatment for severe pulmonary or disseminated histoplasmosis 1.
Diagnosis and Treatment
The diagnosis of histoplasmosis is based on clinical presentation, laboratory tests, and imaging studies.
- For mild to moderate pulmonary histoplasmosis, itraconazole 200 mg three times daily for 3 days, then 200 mg once or twice daily for 6-12 weeks is recommended 1.
- Severe pulmonary or disseminated histoplasmosis requires liposomal amphotericin B 3-5 mg/kg daily for 1-2 weeks, followed by itraconazole 200 mg twice daily for at least 12 months 1.
- Immunocompromised patients may need lifelong suppressive therapy with itraconazole 200 mg daily 1.
Special Considerations
- Patients should be monitored for drug interactions, particularly with itraconazole, which can affect metabolism of many medications 1.
- Histoplasmosis is endemic in the Mississippi and Ohio River valleys in the United States, parts of Latin America, and other areas with the right soil conditions 1.
- The fungus thrives in moist environments rich in nitrogen from bird or bat excrement, explaining why activities like cave exploration, construction, or cleaning chicken coops can increase exposure risk 1.
Key Recommendations
- Liposomal amphotericin B 3-5 mg/kg daily for 1-2 weeks, followed by itraconazole 200 mg twice daily for at least 12 months is the recommended treatment for severe pulmonary or disseminated histoplasmosis 1.
- Itraconazole 200 mg three times daily for 3 days, then 200 mg once or twice daily for 6-12 weeks is recommended for mild to moderate pulmonary histoplasmosis 1.
- Lifelong suppressive therapy with itraconazole 200 mg daily may be required in immunosuppressed patients if immunosuppression cannot be reversed 1.
From the FDA Drug Label
Amphotericin B for Injection USP is specifically intended to treat potentially life-threatening fungal infections: ... histoplasmosis... Histoplasma capsulatum, ... are all inhibited by concentrations of amphotericin B ranging from 0.03 to 1.0 mcg/mL in vitro.
The diagnosis of Histoplasmosis is not explicitly stated in the provided drug labels, but it can be inferred that it is a fungal infection caused by Histoplasma capsulatum. The treatment for Histoplasmosis is amphotericin B (IV), as it is specifically intended to treat this potentially life-threatening fungal infection 2, 2.
From the Research
Diagnosis of Histoplasmosis
- The diagnosis of histoplasmosis depends on understanding the geographic distribution, common clinical presentations, and tests used for diagnosis of histoplasmosis 3
- Clinical syndromes are not specific and histoplasmosis often is overlooked in the evaluation of patients with community-acquired pneumonia, chronic cavitary pneumonia resembling tuberculosis or anaerobic infection, granulomatous inflammatory diseases such as sarcoidosis or Crohn disease, and malignancy 3
- Diagnosis is best made by visualization of yeast in tissue or by culture 4
Treatment of Histoplasmosis
- Treatment is indicated in all immunocompromised patients and those with progressive disseminated disease or chronic pulmonary disease 3
- The preferred agents include liposomal amphotericin B for more severe cases and itraconazole for milder cases and "step-down" therapy following response to amphotericin B 3
- Itraconazole is safe and effective induction therapy for mild disseminated histoplasmosis in patients with AIDS, offering an alternative to amphotericin B in such cases 5
- Patients with moderately severe or severe histoplasmosis should first be treated with amphotericin B and then may be switched to itraconazole after achieving clinical improvement 5
- Voriconazole is not recommended as the initial treatment for histoplasmosis due to increased mortality in the first 42 days when compared to itraconazole 6