Medical Mycology (Biol 4849) Summer 2007

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.