Ostertagia

Ostertagia

The genus is the major causes of parasitic gastritis in ruminants in temperate areas of the world.

Major speices:	Host: Ruminant
·         Ostertagia ostertagi	Cattle (goat also)
·         Ostertagia circumcinta	Sheep and goat
·         Ostertagia trifurcate	Sheep and goat
Minor species:
·         Ostertagia lyrata	Cattle
·         Ostertagia kolchida
·         Ostertagia leptospicularis

Distribution:

·   World wide

·   Especially important in temperate (Type I Disease, mid July) climates

·   In subtropical regions (Type II Disease, late winter & spring) with winter rainfall. 

Identification:

ü   The adults are slender, reddish brown worm up to 1cm long

ü  They are called brown stomach worm because they have this colour when they are fresh.

ü  The cuticle of the anterior extremity may be slightly inflated, transversely striated and rest of the body bears 25-35 longitudinal striation (electron microscope)

ü  Species differentiation is based on the structure of the spicule which usually have two/ three distal branches. The spicules are pigmented brown

ü  The vulva of the female may be covered by small anterior flap.

ü  Found on the surface of the abomasal mucosa

ü  The larval stages occur in the gastric glands and can only be seen microscopically following processing of gastric mucosa.