Trichostrongyloidea

General Appearance

Trichostrongylus - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

• Bursate
• Most members of this superfamily look like short lengths of cotton (typically 0.5-2cm)
• The spicules of each species have a characteristic shape
• The heads have no distinct features

General Life-Cycle

• The egg is approximately 80µm long, oval, thin-shelled, contains 4-16cells (i.e. it is a typical strongyle egg)
• Egg → L1 → L2 → L3 (this occurs on the ground)
• L1 and L2 feed on bacteria
• L3 is the infective stage
• L3 is ensheathed (i.e. the L2 cuticle is retained after moulting as an "outer skin")
• L3 cannot feed, but contains a finite amount of stored food to provide energy for movement
• Infection is by ingestion of the L3
• L3 → L4 → adult (this occurs in the stomach or small intestine)
• Parasitic development initially occurs in gastric glands or intestinal crypts (depending on species)
• Adults are situated on the mucosal surface
• The prepatent period is typically about 3 weeks

Ostertagia

Nematodirus

Dictyocaulus