Bacteriology and Mycology: Pathogenicity

Pathogenicity

PATHOGENICITY

Rhinosporidium lives in soil and it is believed that water is a necessary medium of transmission.
Infection usually results from a local traumatic inoculation and is associated with water activities e.g. swimming in stagnant water.
The infection is typically limited to the mucosal epithelium.
Its life cycle begins with a round endospore(6-10 μm in diameter), which grows to become a thick-walled sporangium (100-450 μm in diameter) that contains up to several thousand endospores.
Mature sporangiospores are approximately 7-9 um in size and escape through a pore that develops in the sporangial wall.
The disease progresses with the local replication of R. seeberi and associated hyperplastic growth of host tissue and a localized immune response.
Infection of the nose and nasopharynx is common; other parts include palpebral conjunctivae, skin, ear,genitals, and rectum.
These polyps are pink to deep red, are sessile or pedunculated, and are often described as strawberrylike in appearance.
Because the polyps of rhinosporidiosis are vascular and friable, they bleed easily upon manipulation.
The polyps are chronic but are not painful.
They can cause obstruction of the respiratory tract resulting in asphyxia.
The rhinosporidial mass has been classically described as a strawberry like mulberry mass.
This mass may extend from the nasal cavity into the nasopharynx and present itself in the oral cavity. These lesions commonly cause bleeding from the nasal cavity.
Rhinosporidium seeberi can also affect the lacrimal gland and also rarely the skin and genitalia.

Rhinosporidiosis in dogs

Rhinosporidiosis is a very rare chronic (long-term) infection that typically occurs in the mucous membranes of dogs.
It most commonly occurs in the nose and nostrils, but can also take hold in the nose and eyes. Rhinosporidiosis belongs to the zoonotic class of fungal infections, meaning that it can be transmitted to humans.
Signs and symptoms of rhinosporidiosis include the following: sneezing, bleeding, wheezing, or labored breathing; an infection of the nostrils with a cauliflower-like growth; a polyp or other growth located near or on the nostril - this growth may be white or yellowish in color and may appear speckled or spotted because of the fungus associated with the growth

Last modified: Monday, 4 June 2012, 6:00 AM

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VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

Pathogenicity

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