History and exam
Key diagnostic factors
common
exposure to fungal spores
The fungus grows in soil and material contaminated with bat or bird droppings. Infection results from inhalation of spores that are disseminated into the atmosphere when soil and/or organic material containing the spores are disturbed. Patients who inhale a large inoculum are more likely to develop severe acute pulmonary histoplasmosis, while a low inoculum exposure is more likely to result in asymptomatic or mildly symptomatic infection.
Histoplasma capsulatum is endemic to the Ohio, Mississippi, and Missouri River valleys in the US, and to Central and South America.[3][16] Activities associated with the development of histoplasmosis pneumonia include cave exploration, close proximity to chicken roosts, demolition and excavation, and gathering wood.
risk factors that impair host defenses
These include stem cell and solid organ transplant, graft-versus-host disease, emphysema, HIV infection, neutropenia, and treatment with corticosteroids or tumor necrosis factor-alpha antagonists.
fever
Seen in up to 80% of patients with symptomatic infection.[1]
headache
Common symptom of acute and chronic infections.
dyspnea
Common symptom of acute pulmonary histoplasmosis, because of airway or vascular compression.
dry or nonproductive cough
Dry cough seen in 70% of acute symptomatic patients.[9]
pleuritic chest pain
Common symptom of acute pulmonary histoplasmosis, seen in 85% to 100% of cases.[1]
anorexia
Common symptom of acute pulmonary histoplasmosis, seen in 85% to 100% of cases.[1]
uncommon
productive cough
Patients with chronic cavitary disease typically present with a productive cough.
Other diagnostic factors
common
abdominal pain
Common symptom of acute pulmonary histoplasmosis.
fatigue
Common symptom of acute pulmonary histoplasmosis.
malaise
Common symptom of acute pulmonary histoplasmosis.
arthralgias
Common symptom of acute pulmonary histoplasmosis.
uncommon
weight loss
Common in chronic or disseminated histoplasmosis. Seen in 26% to 50% of patients.[44]
scattered crackles on chest auscultation
May be found in some patients with mild disease.
bronchial breathing on chest auscultation
May be found in some patients with mild disease.
distant breath sounds on chest auscultation
May be heard during auscultation over a lung cavity in patients with more severe respiratory involvement.
hemoptysis
Associated with chronic pulmonary histoplasmosis.
meningitis-like symptoms
Associated with central nervous system-disseminated histoplasmosis.
skin lesions
Can be seen in disseminated histoplasmosis.
gastrointestinal symptoms
Can be seen in disseminated histoplasmosis.
sepsis-like syndrome
Can be seen in disseminated histoplasmosis.
Risk factors
strong
exposure to fungus
The fungus grows in soil and material contaminated with bat or bird droppings. Infection results from inhalation of spores that are disseminated into the atmosphere when soil and/or organic material containing the spores are disturbed. Patients who inhale a large inoculum are more likely to develop severe acute pulmonary histoplasmosis, while a low inoculum exposure is more likely to result in asymptomatic or mildly symptomatic infection.
Histoplasma capsulatum is endemic to the Ohio, Mississippi, and Missouri River valleys in the US, and to Central and South America.[3][16] Activities associated with the development of histoplasmosis pneumonia include cave exploration, close proximity to chicken roosts, demolition and excavation, and gathering wood.
emphysema
Chronic obstructive lung disease is an independent risk factor for the development of chronic pulmonary histoplasmosis.[1]
HIV infection
Patients infected with HIV with CD4 cell counts <150 cells/mm³ are at high risk for developing disseminated histoplasmosis in conjunction with pulmonary infection.[17]
treatment with tumor necrosis factor (TNF)-alpha antagonists
treatment with corticosteroids
Corticosteroid therapy affects the host immune response at many levels and is a recognized risk factor for acute pulmonary histoplasmosis and disseminated disease.
treatment with immunosuppressants
Immunosuppressants such as calcineurin inhibitors and antilymphocyte globulin are recognized risk factors for histoplasmosis.
neutropenia
Neutropenia resulting from cytotoxic chemotherapy is associated with a high risk of invasive fungal infections including disseminated histoplasmosis.
In non-neutropenic hosts, complement activation and chemotactic factors attract neutrophils to the invading fungal pathogen, leading to damage and growth inhibition. This mechanism is inhibited in neutropenic patients, leading to an increased risk of dissemination.
stem cell and solid organ transplant
graft-versus-host disease
The possibility of invasive and/or disseminated fungal infection should be considered early in the disease course of patients with underlying risk factors including graft-versus-host disease, when increased immunosuppressive therapy is required.[19]
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