‘Nasal Schistosomiasis’ is a chronic parasitic disease of cattle occasionally buffaloes caused by Schistosoma nasalis. Snails of Indoplanorbis Sp act as intermediary hosts. The disease is characterized by granulomatous growths on the nasal mucous membrane and severe respiratory distress for breathing resulting in snoring. The adult parasite lives in the veins of the nasal cavity. Schistosoma are elongated flukes of 30mm long and the female lies in the longitudinal groove of the male. In the buffaloes the disease is mild and sub clinical and there is no granule formation.
Life cycle of the parasite and pathogenesis:
The eggs are passed through the nasal discharges and they hatch in the water and release the miracedia. The miracedia invade suitable intermediary host (water snails) and develop into primary and secondary sporocysts and finally become cercariae. Maturation also takes place in the snails and the fully developed cercariae leaves the snails into water capable of swimming. If a final host comes across the cercariae penetrates the skin or the mucous membranes and reach the final predilected seat via the lymph and blood vessels. During this migration they undergo maturation into adult Schistosoma. The adult Schistosoma lie in nasal blood vessels and produce abscesses. The abscesses rupture and release the eggs into the nasal cavity.
- Granulomatous growths in the nasal cavity.
- Purulent nasal discharge.
- The granulomatous growths enlarge and occlude the nasal passages. Therefore the animal feels respiratory distress and struggles and breaths with a loud sound (Snoring) that can be heard from a distance.
- Classical symptoms of the disease are the primary indication of the disease particularly in the endemic areas.
- Confirmation can be made with identification of the eggs in the nasal discharges or in the nasal scrapings. The eggs are boomerang shaped. Rarely eggs are also seen in the dung.
Anthiomaline is a good drug but reported that the disease recurs again.
Tricalbendazole @20mg/kg body weight can be given.
Treatment of affected animals and snail eradication are the best methods of prevention.