Histoplasmosis infection is usually asymptomatic or minimally symptomatic; however, infection with a large number of organisms or in people with immunodeficiency can result in severe, symptomatic pulmonary infection, which requires treatment.
Risk factors for more severe respiratory disease include inhalation of a large inoculum, impaired cellular immunity (e.g., AIDS/HIV infection, chronic immunosuppressive therapy), age <2 years, and chronic lung disease.
Endemic in temperate regions of the world including the Ohio, Mississippi, and Missouri River valleys in the US, southern Mexico, the Caribbean, and Central and South America. African histoplasmosis is a different clinical entity and is not covered in this topic.
The fungus proliferates well in soil contaminated with bird or bat droppings; therefore, exposure to Histoplasma capsulatum is commonly associated with cave exploration, close proximity to chicken roosts, demolition and excavation, and gathering wood.
Histoplasmosis is an infectious disease caused by the fungus Histoplasma capsulatum. It is not communicable from person to person but is acquired from inhalational exposure to infectious spores found in soil contaminated with bird or bat droppings. African histoplasmosis is a different clinical entity and will not be discussed here.
History and exam
Key diagnostic factors
- presence of risk factors
- dry or non-productive cough
- pleuritic chest pain
- productive cough
Other diagnostic factors
- abdominal pain
- weight loss
- scattered crackles on chest auscultation
- bronchial breathing on chest auscultation
- distant breath sounds on chest auscultation
- meningitis-like symptoms
- skin lesions
- gastrointestinal symptoms
- sepsis-like syndrome
- exposure to fungus
- HIV infection
- treatment with tumour necrosis factor (TNF)-alpha antagonists
- treatment with corticosteroids
- treatment with immunosuppressants
- stem cell and solid organ transplant
- graft-versus-host disease
1st investigations to order
- chest x-ray
- culture of pulmonary secretions
- antigen testing
- immunodiffusion precipitin test
- complement fixation assay
- serology (enzyme immunoassay)
- CT scan of chest
Investigations to consider
- tissue biopsy
latent asymptomatic disease (non-pregnant)
acute pulmonary disease: <4 weeks (non-pregnant)
acute pulmonary disease: >4 weeks (non-pregnant)
chronic pulmonary disease (non-pregnant)
disseminated disease (non-pregnant)
mediastinal granuloma (non-pregnant)
mediastinal fibrosis (non-pregnant)
rheumatological syndrome (non-pregnant)
Zainab A. Malik, MD, MS, FAAP
Pediatrics and Pediatric Infectious Diseases
Mediclinic City Hospital
United Arab Emirates
ZAM has received speakers' honoraria from Merck-MSD.
David L. Goldman, MD
Pediatric Infectious Diseases
The Children's Hospital at Montefiore
DLG declares that he has no competing interests.
Paul Roberts, MD
PR declares that he has no competing interests.
Janak Koirala, MD
Associate Professor of Medicine
Division of Infectious Diseases
Department of Internal Medicine
Southern Illinois University School of Medicine
JK declares that he has no competing interests.
- Community-acquired pneumonia
- Pneumocystis jirovecii pneumonia (PCP)
- Pulmonary tuberculosis
- Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV
- Global guideline for the diagnosis and management of the endemic mycoses
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