Histoplasmosis is an infection caused by Histoplasma capsulatum, a dimorphic fungus. The fungus exists as a mold Mold Mycology at low temperatures and as yeast Yeast A general term for single-celled rounded fungi that reproduce by budding. Brewers' and bakers' yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried. Mycology at high temperatures. H. capsulatum is the most common endemic fungal infection in the US and is most prevalent in the midwestern and central states along the Ohio and Mississippi River valleys. Transmission is through inhalation, and exposure Exposure ABCDE Assessment to soils containing bird or bat droppings increases the risk of infection. Most infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are asymptomatic; however, immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis individuals generally develop acute pulmonary infection, chronic infection, or even disseminated disease. Diagnosis is via different modalities, with the visualization and/or growth of the causative organism made using direct microscopy, histopathology, or culture studies. Management is dependent on disease severity. The antifungal Antifungal Azoles medications that are used include amphotericin B Amphotericin B Macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela. Polyenes and itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles.
Last updated: 1 Apr, 2022
Histoplasmosis is an infection caused by a dimorphic fungus. Remember the following mnemonic to recall how the fungus exists:
Map of the United States illustrating the areas endemic for histoplasmosis
Image: “Map showing areas endemic for histoplasmosis in the US” by CDC. License: Public DomainClinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor varies depending on host immune status and underlying risk factors.
Photomicrograph of a methenamine silver-stained tissue sample extracted from a patient with histoplasmosis:
Note the presence of typical
yeast
Yeast
A general term for single-celled rounded fungi that reproduce by budding. Brewers’ and bakers’ yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried.
Mycology cells, some of which were undergoing replication by
budding
Budding
Mycology.
Macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation in lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node containing numerous Histoplasma capsulatum (Diff-Quick stain)
Image: “ Macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation in lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node containing numerous Histoplasma capsulatum” by Rosen Y. License: CC BY-SA 2.0
Chest X-ray
Chest X-ray
X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs.
Pulmonary Function Tests:
Diffuse pulmonary infiltration due to acute pulmonary histoplasmosis caused by Histoplasma capsulatum
Condition | Treatment |
---|---|
Moderate pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis or symptoms lasting > 4 weeks | Itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |
Moderately severe to severe pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis | Amphotericin B Amphotericin B Macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela. Polyenes + itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |
Chronic pulmonary histoplasmosis | Itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |
Mild disseminated histoplasmosis: mild symptoms with single focus Focus Area of enhancement measuring < 5 mm in diameter Imaging of the Breast (no CNS involvement) | Itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |
Severe disseminated histoplasmosis without CNS involvement | Amphotericin B Amphotericin B Macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela. Polyenes + itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |
CNS involvement | Amphotericin B Amphotericin B Macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela. Polyenes (prolonged) + itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles |