Schistosomes

SCHISTOSOMES

Amongst trematodes, the blood flukes are different in the following manner :

  • Male and female are separate with marked sexual dimorphism. Male is short and thick; female is long and slender.
  • Appear like a nematode.
  • Pharynx absent.
  • Intestinal caeca united posteriorly to form a common caeca.
  • Male lodges the female in an incurved groove, gynaecophoral canal.
  • Life cycle involves three larval stages viz. miracidium, sporocyst and furcocercous cercaria. Redial stage is absent.

Schistosoma nasale (Nasal blood fluke)

Host Cattle, buffalo, rare in sheep, goats and horses
Location Nasal veins
Intermediate host Indoplanorbis exustus
Pathogenesis Nasal schistosomosis or snoring disease or nasal granuloma in cattle
  • Suckers are weak and close together.
  • Two or four testes in the anterior region behind the ventral suckers.
  • The integument is coarsely tuberculated in male.
  • Ovary in front of common caeca.
  • Uterus with 1 or 2 eggs.
  • Section of nasal granuloma (Actinobody)
  • Cut section of egg with miracidium surrounded by numerous phagocytic cells in a radial manner resulting in actinobody or pseudo tubercle formation.

Schistosoma spindale

Host Cattle, buffalo, sheep and goats
Location Portal and mesenteric veins
Intermediate host Indoplanorbis exustus
Pathogenesis Visceral schistosomosis
  • Similar to S. nasale.
  • The integument is smooth in male.
  • Three to seven testes in the anterior region behind the ventral suckers.

Schistosoma indicum

Host Cattle, buffalo, sheep, goats, equines and camels
Location Portal and mesenteric veins
Intermediate host Indoplanorbis exustus
Pathogenesis Visceral schistosomosis
  • Cuticle is finely tuberculated posterior to the ventral sucker.
  • Five to twelve testes in the anterior region behind the ventral sucker.

Schistosoma incognitum (S. suis)

Host Pigs and dogs
Location Portal vein
Intermediate host Lymnaea luteola
Pathogenesis Visceral schistosomosis
  • Very small fluke.
  • Moderately tuberculated cuticle.
  • Two to seven testes in the anterior region behind the ventral suckers.

Ornithobilharzia turkestanicum

Host

Cattle, buffalo, sheep and goats
Location Portal and mesenteric veins
Intermediate host Lymnaea acuminata
Pathogenesis
  • Resembles Schistosome in all characters.
  • Possess large number of testes (above 60).

Last modified: Tuesday, 19 June 2012, 9:53 AM