From the Guidelines
Histoplasmosis should be treated with itraconazole (200mg twice daily) for 6-12 weeks for moderate to severe pulmonary infections, while severe or disseminated infections require initial treatment with amphotericin B (0.7-1.0 mg/kg/day) for 1-2 weeks, followed by itraconazole for at least 12 months, as recommended by the Infectious Diseases Society of America 1.
Diagnosis and Treatment
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum, primarily affecting the lungs but capable of disseminating throughout the body in severe cases. The infection is acquired by inhaling fungal spores found in soil contaminated with bird or bat droppings, particularly in the Ohio and Mississippi River valleys.
- Diagnosis typically involves:
- Fungal cultures
- Antigen testing in urine or serum
- Histopathology
- Treatment depends on disease severity, with mild cases often resolving without medication.
Treatment Options
For moderate to severe pulmonary histoplasmosis, itraconazole (200mg twice daily) is typically prescribed for 6-12 weeks. Severe or disseminated infections require initial treatment with amphotericin B (0.7-1.0 mg/kg/day) for 1-2 weeks, followed by itraconazole for at least 12 months 1.
- Immunocompromised patients may need lifelong suppressive therapy with itraconazole (200mg daily).
Prevention
Prevention focuses on avoiding exposure to contaminated soil, bird roosts, and bat-inhabited caves, with particular caution advised for immunocompromised individuals when in endemic areas.
- Most infections (90%) are asymptomatic or cause mild flu-like symptoms, but immunocompromised individuals face higher risks of severe disease.
Key Considerations
- Blood levels of itraconazole should be obtained to ensure adequate drug exposure 1.
- Antigen levels should be monitored during therapy and for 12 months after therapy is ended to monitor for relapse 1.
- Persistent low-level antigenuria may not be a reason to prolong treatment in patients who have completed appropriate therapy and have no evidence of active infection 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 the treatment for Histoplasmosis (Histoplasma capsulatum infection) is Amphotericin B (IV), as it is specifically intended to treat this potentially life-threatening fungal infection 2. The drug shows in vitro activity against Histoplasma capsulatum 2.
- Key points:
- Diagnosis: Not explicitly stated in the provided drug labels.
- Treatment: Amphotericin B (IV) for potentially life-threatening Histoplasmosis.
- Mechanism of action: The drug acts by binding to sterols in the cell membrane of susceptible fungi, resulting in a change in membrane permeability.
From the Research
Diagnosis of Histoplasmosis
- The diagnosis of histoplasmosis is based on clinical findings, laboratory tests, and imaging studies 3.
- Patients with histoplasmosis may present with symptoms such as fever, fatigue, and weight loss, and may have abnormal laboratory results, such as elevated alkaline phosphonate and low albumin levels 4.
Treatment of Histoplasmosis
- The treatment of choice for severe histoplasmosis is amphotericin B, while itraconazole is given for mild to moderate histoplasmosis 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 4.
- 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 4.
- Voriconazole is not recommended as the initial treatment for histoplasmosis due to its association with increased mortality in the first 42 days of treatment compared to itraconazole 5.
- Posaconazole may be a useful salvage treatment option for histoplasmosis involving a variety of infected tissues and organs 6.
- For adult patients living with HIV, preferred treatment regimens for initial therapy include liposomal amphotericin B for severe disease, or itraconazole for mild to moderate disease, followed by itraconazole maintenance therapy for at least one year 7.
Prevention of Histoplasmosis
- Avoidance of contact with bird or bat guano or inhalation of aerosolized soil in endemic regions may reduce the risk of histoplasmosis 7.
- Adherence to effective antiretroviral therapy is the most important strategy for reducing the incidence of life-threatening histoplasmosis 7.
- Itraconazole prophylaxis reduces the risk for histoplasmosis in patients with CD4 counts <100/µL but is not associated with survival benefit and is primarily reserved for use in outbreaks 7.