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Schistosoma nasale infection

ISSN 2398-2993

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Synonym(s): nasalis nasal vein veins mucosa India trematode egg snail blood flatworm worm fluke rhinitis mucopurulent discharge sneezing dyspnea dyspnoea abscess abscesses


  • Cause: Schistosoma nasale, a snail-borne blood fluke/trematode.
  • Signs: rhinitis, mucopurulent nasal discharge, sneezing, dyspnea, and snoring.
  • Diagnosis: physical examination can reveal snoring respiratory sounds and presence of nodular lesions in the nasal cavity. Rhinoscopic detection of congestion in the nasal mucosa. Microscopic identification of S. nasale eggs in nasal discharges/washings/scrapings.
  • Treatment: anthiomaline (Lithium Antimony thiomalate) is the drug of choice. Praziquantel and other anthelmintics have been also used.
  • Prognosis: favorable with prompt diagnosis and timely treatment.

Presenting signs

Acute presentation

  • Often presents with sneezing, thick mucus nasal discharge, snoring, and congestion of the nasal mucosa.

Geographic incidence

  • Nasal schistosomiasis is prevalent in the Indian subcontinent, particularly in grazing areas with water-logged and marshy field conditions.
  • Incidence of clinical disease is higher in cattle compared with buffalos .

Age predisposition

  • In the author’s experience, the number and severity of lesions typically increase with age although data to support this observation is unavailable at the time of publication.

Gender predisposition

  • The clinical signs may become aggravated with stress.

Breed/Species predisposition

  • Buffaloes are much less affected by nasal schistosomiasis, than cattle, and exhibit only pinhead-sized eruptions and congestion of the nasal mucosa.
  • Sheep, goats and horses are rarely affected.

Public health considerations

  • Humans are the natural host for a number of Schistosoma spp, particularly in different parts of Asia and Africa, but S. nasale only infects ungulates.
  • Schistosomes of mammalian and avian origin can cause a cutaneous inflammatory response in human skin, which is commonly known as cercarial dermatitis or swimmer's itch.

Cost considerations

  • Schistosomiasis can cause significant morbidity and adversely affects the production in cattle and other farm animals.



  • S. nasale, a digenetic trematode, is a member of genus Schistosoma, family Schistosomatidae.
  • Inhabits the blood vessels of the nasal mucosa of cattle and occasionally buffaloes.
  • Has a two host-life cycle with a sexual adult stage inside the mammalian vertebrate host and asexual stages in the intermediate host, a freshwater snail, Indoplanorbis exustus.
  • Is transmitted to the animals through contact with water infested with cercariae and possibly also by ingestion of cercariae when drinking.
  • Is genetically related to the African/Indian Schistosoma species rather than the East Asian Schistosoma species.

Predisposing factors


  • Keeping animals on pasture with free access to fresh-water bodies, including pools, ponds and paddy fields where infected snails reside.


  • The presence of fresh-water snails (Indoplanorbis spp) and direct skin contact with water infested with the infective stage cercariae of S. nasale worms.


  • Transmission of infection to the susceptible animal occurs by penetration of the skin by cercariae of S. nasale when animals forage or drink in water.
  • The cercariae grow into adult male and female flukes as they migrate in the circulation until they settle in the nasal vein.
  • The female flukes lay their eggs in the nasal vein, which enter the nasal mucosa where they trigger an inflammatory reaction leading to rhinitis, hemorrhagic and/or mucopurulent nasal discharge and development of granulomatous cauliflower-like growths in the nasal cavity.
  • These abnormal growths on the nasal mucosa cause partial obstruction of the nasal cavity, which leads to dyspnea and snoring sounds during breathing.
  • The main pathogenic effects are attributed to the fluke eggs owing to their sharp terminal spine, which causes micro-abscesses and other pathologies in the nasal mucosa.
  • The matured eggs containing fully developed miracidia are released in nasal discharges during sneezing or drinking.


  • The pre-patent period ranges from 50-103 days.


  • S. nasale is widely distributed in various parts of India and Indian subcontinent.
  • The prevalence rates reported in cattle from different regions range from 1-20.9%.
  • Nasal schistosomiasis has been also reported in Bangladesh, Malaysia, Myanmar, Nepal, Pakistan, and Sri Lanka.
  • Freshwater snails of the species Indoplanorbis exustus serve as intermediate hosts for S. nasale.
  • The overall prevalence of S. nasale is highest during the rainy season and winter and is lowest during summer, but in monsoon zones, seasonality is less marked.
  • Warm, moist climatic conditions are favorable for the growth of intermediate host snails and the development of immature fluke, hence more cercariae are shed by snails during the warm, rainy seasons.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Sekhar S C, Prasuna K, Jahan A, Khatoon S & Rao G S (2021) Persistence of nasal schistosomiasis in cattle: a clinical case report. J Entomol Zool Stud (2), 1350-1352 JEZS.
  • Shende V, Kalyankar A, Kadam H, Sontakke S, Potdar V & Khadse J (2021) Incidence of nasal Schistosoma infection in Holstein-Friesian (HF) cross breeding bull: a clinical case report. Ind J Pure App Biosci (3), 73-75 IJPAB.
  • Yogeshpriya S, Selvaraj P, Saravanan M, Ramkumar P K & Asmitha S (2021) Conventional borescope in the evaluation and management of nasal Schistosomiasis in a bullock. Int J Curr Microbiol App Sci 10 (01), 3024-3027 ResearchGate.
  • Raut M M, Kaore M, Chavan C A, Kolte S W & Kurkure N V (2019) Pathology and phylogenetic analysis of Schistosoma nasale infection in cattle in Nagpur area. Ind J Vet Pathol 43 (3), 217-220 VetMedResource.
  • Basu A K & Bhattacharyya D (2018) Schistosoma nasale Rao, 1933 (Trematoda: Schistosomatidae) causative agent of nasal schistosomiasis of animals in the Indian subcontinent – an overview. CAB Reviews 13 (53), 1-11. CabDirect.
  • Didugu H & Narasimha Reddy Ch E (2017) Incidence of nasal schistosomiasis in graded Murrah buffaloes. Buffalo Bulletin 36 (1), 143-146 BuffaloBulletin.
  • Agrawal M C & Alwar V S (1992) Nasal schistosomiasis: a review. Helminthol Abstr 61, 373-384.

Other sources of information

  • Kolte S (2013) Snoring Disease in Cattle Schistosoma Nasale (video). Website: