History and morphology

HISTORY AND MORPHOLOGY
  • Histoplosma capsulalum and H. farciminosum cause clinical disease in horses.
  • Epizootic lymphangitis is characterised by a cord-like appearance of the subcutaneous lymphatic vessels, especially of the limbs, neck and chest and the development of a series of pyogranulomas, the discharge from which contains yeast-like cells of the pathogen. Rarely, infection may lead to pneumonia and conjunctivitis.
  • Histoplasmosis caused by H. capsulatum has been recognised in horses in certain areas of the world.
  • Histoplosma farciminosum (Synonyms: Cryptococcus farciminosum, Zymonema farciminosum, Histoplasma capsulatum var. farciminosum) is the cause of epizootic lymphangitis.
  • Histoplosma farciminosum will be used to name the agent, although according to Ajello the organism does not belong to the genus Hisloplosma.
  • Epizootic lymphangitis is a disease which is distributed world-wide, with endemic foci in North Africa and Asia.
  • The organism was first demonstrated in pus by Rivolta in 1873 but was not successfully cultivated until 1896 when the first pure cultures were obtained by Tokishiga in Japan.
  • The yeast form of the organism appears in pus as a double-contoured oval or ovoid body, measuring 2.5-3.5 µm by 3-4 um. The saprophytic stage is mycelial form.
Last modified: Monday, 4 June 2012, 6:37 AM