Difference between revisions of "Histoplasmosis"
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(Created page with '{| align="right" |<gallery>Image:Histoplasmosis canine spleen.jpg|<center><p>'''Histoplasmosis in a canine spleen'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. B…') |
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**Stain with Giemsa or Wright and examine under oil immersion lens | **Stain with Giemsa or Wright and examine under oil immersion lens | ||
− | *Present intracellularly in [[Macrophages | + | *Present intracellularly in [[Macrophages|macrophages]] as oval yeast cells with few buds |
**Clear halo is seen around the darker staining central material | **Clear halo is seen around the darker staining central material | ||
Revision as of 12:39, 12 June 2010
- Histoplasma capsulatum
- Non-contageous, systemic mycosis
- Commonly pulmonary infections occur
- Other organs can be involved
- Involves the reticuloendothelial system
- Intestinal form can also occur
- Acute and chronic disease can occur
- Endemic to the USA
- Isolated cases have been reported in Europe
- Respiratory infection
- Infection via ingestion can also occur
- Affects dogs, cats, cattle, horses and humans
- Found in soil contaminated by bird droppings, decaying vegetation and in caves inhabited by bats
- Fine, branching, septate hyphae with smooth-walled pyriform to spherical microconidia and large, thick-walled tuberculate macroconidia on simple conidiophores
- Dimorphic fungi
- Hard to demonstrate in smears as the organisms is very small
- Stain with Giemsa or Wright and examine under oil immersion lens
- Present intracellularly in macrophages as oval yeast cells with few buds
- Clear halo is seen around the darker staining central material
- Grows on Sabouraud's Dextrose agar
- Creamy white colonies, turning tan coloured and then brown
- Also grows on Blood agar
- Small, white yeast-like colonies
- Test using immunodiffusion, complement fixation and counterimmunoelectrophoresis
- Skin test of little value as it only indicates exposure
- Treatment with Amphotericin B
- If Amphotericin B is contra-indicated, imidazoles can be given orally
- The prognosis is poor in acute and disseminated cases