Rhinosporidiosis is an infectious disease caused by an aquatic protozoan previously considered to be a fungus. The etiologic agent of rhinosporidiosis, Rhinosporidium seeberi, is closely related to several protoctistiae fish pathogens. The infection affects nasal mucous membranes and ocular conjunctivae of humans and animals, producing slowly growing masses that degenerate into polyps. It is endemic in Sri Lanka, South India, South America and Africa.
The endospore of this organism colonizes the nasal epitheliam and grows to become a thick-walled sporangium of 100-450 µm in diameter that contains up to several thousand endospores (Image 2 & 3).