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Source: Carver PL. Invasive Fungal Infections. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG,
Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th edition. http://accesspharmacy.com/content.aspx?aid=8005562.
Accessed June 23, 2012.
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- Systemic fungal infection
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- Inhalation of dust-borne Histoplasma
capsulatum
- Acute histoplasmosis may occur in epidemics when soil disturbed.
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- Aerosolized H. capsulatum inhaled
and settles in lungs
- Tissue granulomas form over 2–4 months.
- Foci become encapsulated and calcified over several years.
- Low-inoculum exposure results in benign disease course.
- Higher-inoculum exposure results in acute, self-limited illness
- Fever
- Chills
- Headache
- Myalgia
- Nonproductive cough
- Chronic pulmonary histoplasmosis
- Progressive
disease over period of years
- Cavitation
- Bronchopleural fistulas
- Involvement of both lungs
- Pulmonary insufficiency
- Death
- Immunocompromised hosts
- Progressive, disseminated histoplasmosis
- Acute disseminated histoplasmosis
- Infants and young children: fatal in 1–2 months
if untreated.
- Adults: untreated patients ill for 10–20 years,
with long asymptomatic periods.
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- Localized along Ohio and Mississippi River valleys in
United States.
- Found in nitrogen-enriched soils, particularly those contaminated
by avian or bat guano.
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- Immunosuppression (e.g., AIDS)
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- Immunocompromised hosts
- Adults with AIDS
present with acute form of disseminated disease that resembles syndrome
seen in infants and children.
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- Chronic pulmonary histoplasmosis
- Chronic
pulmonary symptoms
- Apical lung lesions
- Acute disseminated histoplasmosis
- Infants
and young children
- Unrelenting fever
- Anemia
- Leukopenia or thrombocytopenia
- Enlargement of liver, spleen, and visceral lymph nodes
- Gastrointestinal (GI) symptoms: nausea, vomiting, diarrhea
- Adults
- Long asymptomatic periods interrupted
by
- Weight loss
- Weakness
- Fatigue
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Means of Confirmation
and Diagnosis
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- Serologic testing
- Complement fixation
- Immunodiffusion
- Latex antigen agglutination antibody tests
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- Culture
- Identification
of mycelial isolates from clinical cultures can be made by conversion
of mycelium to yeast form (requires 3–6 weeks) or by more
rapid (2 hours) and 100%-sensitive DNA probe that recognizes
ribosomal DNA.
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+++
Diagnostic Procedures
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- Bone marrow biopsy and culture best method to establish
diagnosis in AIDS patients with progressive disseminated histoplasmosis.
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Differential Diagnosis
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++
- Resolution of clinical abnormalities
- Prevention of relapse
- Eradication of infection
- Chronic suppression
for immunosuppressed patients
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- Asymptomatic or mildly ill patients and patients with
sarcoid-like disease generally do not benefit from antifungal therapy.
- Therapy may be helpful in symptomatic patients whose conditions
have not improved during first month of infection.
++
- Recommended therapy for treatment of histoplasmosis summarized
in Table 1.
- Patients with mild, self-limited disease, chronic disseminated
disease, or chronic pulmonary histoplasmosis with no underlying
immunosuppression can usually be treated with oral itraconazole or
IV amphotericin B.
- AIDS patients
- Intensive 12-week primary (induction
and consolidation therapy) antifungal therapy followed by lifelong
suppressive (maintenance) therapy with itraconazole.
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