Crcooper01.people.ysu.edu
Medical Mycology (Biol 4849) Summer 2007
Dr. Cooper
Histoplasmosis
Synonyms: African histoplasmosis, Histoplasma capsulatum, Histoplasma duboisii, North American histoplasmosis, Darling disease
• Histoplasmosis
• intracellular myotic infection of the reticuloendothelial system, which is part of the immune system, such as lymph nodes
• Mississippi- Ohio River Valley in the U.S. is the major endemic region
• Africa, Australia, India, and Malaysia are also endemic regions
• Histoplasma capsulatum is known as North American Histoplasmosis
• Histoplasma duboisii is known as African Histoplasmosis
• Presentation of Disease
– “coin” like lesions on histocytes and reticuloendothelical cells
– Pulmonary nodules are circular calcification which makes them visible on chest x-rays
– Histoplasma capulatum yeast are found in the center of the lesions
• Case Report 1
• CT scan of the cerebrum revealed a great dilatation of the cerbral ventricles due to the obstruction of the sylvian aqueduct.
• CT scan of abdominal organs revealed ascities and retroperitoneal lymphadenopathies.
• CSF showed decreased glucose and elevated protein values.
• After two weeks after admission, pt. receive antifungal drugs starting with amphotericin and fluconazole.
• Pt. expires eight day later.
• Autopsy reveals edema and areas of bronchopneumonic consolidations in both lungs; enlarged hilar nodes, which constricted the main bronchus; the abdominal lymph nodes were also swollen; there was also hepatosplenomegaly; signs of leptomeningitis and many small areas of inflammation in the brain parenchyma.
• Case Report 2
• May 2007:
• Upon examination, cervical lymphadenopathy and hepatomegaly was noted. The lesion mimic cancer.
• Elective surgery was performed.
• Histopathological examination of the resected segment of the sigmoid colon revealed small oval, narrow-based budding yeast. Suggestive of H. capsulatum.
• June 2007:
• Patient was treated with I.V. amphotericin
• Significance: Histoplasmosis has been reported both in immunocompetent as well as immunocomporomised patients with dissemenated forms being more common in the latter group.
• In HIV positive patients the prevalence of histoplasmosis varies from 5% - 32% depending on the endemicity of the disease.
• There was no prior clinical suspicion of HIV infection in patient.
• There was involvement of only the sigmoid colon and there was no associated hepatosplenomegaly, lymphadenopathy, or orophyaryngeal ulcer.
• H. capsulatum may present as carcinoma. Good differential diagnosis and hx may help to avoid making the same mistake.
• Case Report 3
Sobrinho FP., Negra MD., Queiroz W., et al. “Histoplasmosis of the Larynx.” Rev Bras Otorrinolaringol. 2007; 73(6): 857-61. Article acquired on June17, 2008 from Pub Med.
• Pt. presented hoarseness, progressive dysphagia, and weight loss.
• Pt. has hx of HIV since 1996.
• Laryngoscopy showed white necrotic lesion spread throughout his larynx, edema and exophytic lesion in the upper right border of the epiglottis.
• There was no lesion on the skin.
• Occurrence is high in immunosuppressed and elderly patients, and more commonly in men.
• Fever, weight loss, asthenia, liver and spleen enlargement and oral mucosa lesions are very common.
• Infection can spread to other organs such as bone marrow, lymph nodes, adrenal glands, G.I. tract, tongue and oral mucosa.
• Acute pulmonary histoplasmosis usually occurs in children below one year of age or in severe immunosuppresessed patients.
• Weight loss, fever, liver and spleen enlargement , shock, respiratory failure and disseminated intra-vascular coagulation (DIVC) are common.
• Histopathology
• Infection is acquired through the inhalation of histoplasma capsulatum microcondia, which is the spores of this fungi
• Lungs, bones, and skin are the most frequent affected site from this fungus
• It may coexist with other mycoses or even diseases, such as emphysema and tuberculosis
• Causative Organism:
– Histoplasma capsulatum
• Clinical Manifestations
• 95% of cases of histoplasmosis are unapparent or benign
• 5% have chronic progressive lung disease, chronic cutaneous or systemic disease, or fatal systemic disease
• The disease may mimic tuberculosis
Symptoms:
• Lymph nodes- inflamed lymph nodes
• Adrenal Glands- enlargement
• Central Nervous System- chronic meningitis
• GI tract- oral ulcers, small bowel micro and macro ulcers
• Eyes- inflamed inner eye
• Skin- papular to nodular rash
• Genitourinary tract- bladder ulcer, penile ulcers
• Laboratory Aspects
Virulence Factors:
• In most cases, inhalation of microconidia, which in turn germinates into yeasts within the lung is the cause of virulence
Diagnosis:
• Skin scrapings examined using 10% KOH
• Body fluids, such as blood, should be centrifuged and examined
• Tissues should be stained using a Gram stain and examined
• Epidemiology and Ecology
• Ecology
- found in moderate climates, humidity, and soil characteristics
- bird and bat excrement enhances the growth of the organism in soil by accelerating sporulation
• Epidemiology
- Infects mostly immunosuppressed individuals, children less than 2 years old, and elderly people use of broad spectrum antibiotics
- air currents carry spores which exposes individuals who breath in the contaminated air
• Treatment and Prevention
Treatment
• Long-term therapy with antifungal agents at increasing doses until resolution of symptoms, such as amphotericin B, fluconazole, and intraconazole
• Surgical procedures to remove the ulcer may also be done
Prevention
• No direct away to avoid this fungal infection because it is airborne
• Avoid areas with accumulations of bird or bat droppings.
• Before starting an activity having a risk for exposure to H. capsulatum, consult the NCID Document Histoplasmosis: Protecting Workers at Risk
• References
• “Histoplasmosis.”
Dimorphic_systemic/Histoplasmosis/index Article acquired on June
16, 2008 from Mycology Online.
• Histoplasmosis.”
Org/mycoses/human/histo/histoplasmosis_index.htm Article acquired on June 16, 2008 from Doctor Fungus.
• “Histoplasmosis Due to Histoplasma Capsulatum.”
Org/mycoses/human/histo/histoplasmosis_c.htm Article acquired on
June 16, 2008 from Doctor Fungus.
• Histoplasmosis Due to Histoplasma Duboisii.”
Org/mycoses/human/histo/histoplasmosis_d.htm Article acquired on
June 16, 2008 from Doctor Fungus.
• Sehgal S., Chawla R., Loomba PS, Mishra B. “Gastrointestinal Histoplasmosis Presenting As Colonic Pseudo-tumour.”
Indian Journal of Medical Microbiology. 2008; 26(2) 187-189. Article
acquired on June17, 2008 from Pub Med.
• Severo LC., Zardo IB., Roesch W., and Hartmann AA. “Acute Disseminated
Histoplasmosis In Infancy in Brazil: Report of a case and Review.”
Rev Iberoam Micol. 1998; 15:48-50. Article acquired on June17, 2008 from Pub Med.
• Sobrinho FP., Negra MD., Queiroz W., et al. “Histoplasmosis of the Larynx.”
Rev Bras Otorrinolaringol. 2007; 73(6): 857-61. Article acquired on June17, 2008 from Pub Med.
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