Rhinosporidiosis (Fungal-like agent)
Rhinosporidiosis is a chronic, non-fatal, granulomatous mycotic infection of nasal mucosa caused by Rhinosporidium seberi. R. seberi is currently classified as an aquatic protozoan of the class Mesmomycetozoea and order Dermocystida. The disease is characterized by the formation of polyps (growth) on the mucosa of the nose and rarely on other parts of the body. Natural infection has been recorded in man, cattle, horse and mule. The disease is endemic in India. It is believed that fungus grows in the mud and slime of ponds where the water is stagnant. The infection is maintained by the diseased human beings and animals who drain the exudate into the water holes while visiting such water reservoirs either for drinking or bathing purpose. This fungus has not been successfully cultivated in artificial media so far though there have been several claims. Utilisation of the same pond by man and animals appear to be a predisposing cause. Transmission studies have been a failure and how the disease remains in the population has not been elucidated beyond doubt.
Symptoms: Man and animals usually acquire the infection from the contaminated ponds or other water reservoirs. There is always a history of trauma or abrasion to the nasal submucosa before the appearance of lesion. As a result of polyps in the nose, the animal feels great difficulty in respiration. Therefore, snoring sound or difficulty in can be heard from some distance. Affected animals show dyspnoea and mucopurulent nasal discharge from both the nostrils. The discharge may sometimes become blood tinged. In our country experience has shown that bullock whose nasal septum are punctured for nose string at the age of 3 years for ploughing the field, are more prone to rhinosporidiosis than cows. The polyps (growth) are red, lobed, painful and bleed readily when traumatized. These growths can be easily seen and palpated in the nasal cavity.
Diagnosis: Since R. seeberi cannot be cultured, the diagnosis depends upon the histological examination of the polyps. The exudate or material from polyps should be examined microscopically in 10 % potassium hydroxide solution or water after putting cover-glass on the specimen. The positive smear or tissue show scattered sporangia (cyst) 6-340 µ m in diameter. They contain many round, thickened, chitinous walled sporangiospores 6-7 µm in diameter. Differential diagnosis should be made from nasal schistosomiasis (nasal granuloma) and chronic allergic rhinitis. In the former case eggs of Schistosoma nasale are detected in the nasal discharge whereas in the latter case no organisms are found in the smear.
Treatment and prevention: No drug which can act against rhinosporidiosis is available. Surgical removal of the infected growth is the only way of treatment. However, the growth may also reappear after a few months. The disease may be prevented if the man and animals are not allowed to visit the contaminated ponds or lakes which serve as the man reservoir of infection.