''Schistosoma nasale'' is a species of

digenetic Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms (known as ''flukes'') with a syncytial tegument and, usually, two suckers, one ventral and one oral ...

trematode Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host ...

in the family

Schistosomatidae Schistosomatidae is a family of digenetic trematodes with complex parasitic life cycles. Immature developmental stages of schistosomes are found in molluscs and adults occur in vertebrates. The best studied group, the blood flukes of the genus ...

. ''S. nasale'' inhabits blood vessels of the

nasal mucosa The nasal mucosa lines the nasal cavity. It is part of the respiratory mucosa, the mucous membrane lining the respiratory tract. The nasal mucosa is intimately adherent to the periosteum or perichondrium of the nasal conchae. It is continuous w ...

and causes " snoring disease" in cattle, but remains symptomless in buffaloes though extruding its eggs in nasal discharge. The first intermediate host is a freshwater snail ''

Indoplanorbis exustus ''Indoplanorbis'' is a genus of air-breathing freshwater snail. Its Monotypic taxon, only member species is ''Indoplanorbis exustus'', an aquatic animal, aquatic pulmonate gastropod mollusk in the family (biology), family Planorbidae, the sheep, ...

'' that may be the sole natural intermediate host for ''Schistosoma nasale'' (and other two ''Schistosoma'' species) on the Indian sub-continent.

Signs and symptoms

The clinical symptoms in cattle include a cauliflower-like growth or granuloma in the nasal cavity, associated with a "snoring" sound and profuse mucopurulent discharge. In the endemic areas, there are some local cattle which remain negative for ''S. nasale'' eggs, others excrete eggs but without exhibiting symptoms, while a large number exhibit symptoms with presence of the eggs in nasal discharge.Agrawal MC 2012. Schistosomes and schistosomiasis in South Asia. Springer (India) Pvt Ltd. New Delhi. page 351. A different form of nasal schistosomiasis where local cattle are negative for ''S. nasale'' but local buffaloes carry it without showing any symptoms has been shown to exist at Jabalpur, Madhya Pradesh; there, cross-bred cattle exhibit snoring disease symptoms with eggs in their nasal discharge. Anthiomaline was the drug of choice, but this leads to relapse of the symptoms after two months of the treatment. Praziquantel proved better than any other drug. Recently, Dr. M. C. Agrawal has successfully treated cases of nasal schistosomiasis by administering

triclabendazole Triclabendazole, sold under the brand name Egaten among others, is a medication used to treat fascioliasis and paragonimiasis. It is very effective for both conditions. Treatment in hospital may be required. It is taken by mouth with typically ...

. Nevertheless, there are all chances of killing susceptible blood flukes by these less effective drugs resulting in existence of more resistant schistosome population in future generations causing more problems. ''Schistosoma nasale'' eggs are boomerang or palaquine shaped.

History

''Schistosoma nasale'' was identified in 1933 by Maharaj Anant Narayanan Rao (1875–1940) at

Madras Veterinary College The Madras Veterinary College, the college affiliated with Tamil Nadu Veterinary and Animal Sciences University, is a veterinary college in Vepery, a suburb of Chennai, Tamil Nadu, India. The college was established on 1 October 1903 in a smal ...

Tamil Nadu Tamil Nadu (; , TN) is a States and union territories of India, state in southern India. It is the List of states and union territories of India by area, tenth largest Indian state by area and the List of states and union territories of India ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, as a causative agent for "snoring disease" in cattle. Snails initially implicated in transmission of ''Schistosoma nasale'' as the first intermediate host included ''

Lymnaea luteola ''Radix luteola'' is a species of freshwater snail, an aquatic gastropod mollusc in the family Lymnaeidae. Placement of this species within the genus ''Radix'' was confirmed by Correa et al. (2010).Correa C. A., Escobar J. S., Durand P., Ren ...

'' and ''

Lymnaea acuminata ''Lymnaea acuminata'' is a species of freshwater snail in the family Lymnaeidae. It is native to South Asia, where it occurs in Bangladesh, Burma, India, Nepal, and Pakistan. There it is a widespread and common species.Budha, P.B., Dutta, J. & ...

'', but experimental work of Dutt and Srivastava (1962) conclusively proved ''Indoplanorbis exustus'' as the sole intermediate host of ''S. nasale''.

References

This article incorporates CC-BY-2.0 text from Liu 2010. {{Taxonbar, from=Q7431532 Diplostomida Parasitic animals of mammals Veterinary parasitology Bovine diseases Animals described in 1933