Friday, June 25, 2010

Rhinosporidiosis still an enigma

Rhinosporidiosis has been defined as a chronic granulomatous disease characterized by production of polyps and other manifestations of hyperplasia of nasal mucosa. The etiological agent is Rhinosporidium seeberi.

Theories of mode of spread:
  1. Demellow's theory of direct transmission
  2. Autoinoculation theory of Karunarathnae (responsible for satellite lesions)
  3. Haematogenous spread - to distant sites
  4. Lymphatic spread - causing lymphadenitis (rarity)

    Reasons for endemicity of Rhinosporidiosis:
    It has to be explained why this disease is endemic in certain parts of South India and in the dry zone of Srilanka. If stagnant water could be the reason then the chemical and physical characteristics of the water needs to be defined. In addition other aquatic organisms may also be playing an important synergistic reaction. This aspect need to be elucidated. Text book of microbilogy is repleate with examples of such synergism i.e. lactobacillus with trichomonas, and Wolbachia with filarial nematodes.

    These studies prompted Prof Ahluwallia et al to conclude that:

    1. Chronic inflammation almost always precedes rhinosporidiosis
    2. During this period if the patient consumes dry / fried tapioca and is malnourished it invariably leads to granulomatous polyp in the nose.
    3. Dirty pond water in which the patient takes bath causes inflammation of the nasal mucosa

      The following are the reasons making the study of this disease rather difficult:

      1. Till date no pure extract containing rhinosporidial trophozoite / spores / sporangium is available
      2. Attempts made to culture these organsim have not been successful
      3. The role of electron dense bodies in disease propagation is yet to be studied. Studies have shown that these electron dense bodies stain positively to Feulgen staining indicating that it contains nucleic acids
      4. The absence of good animal model for studying this disease is one major drawback.





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