VPA 211: General Veterinary Parasitology and Helminthology (3+1)

LIFE CYCLE

• Eggs are passed in the faeces of host. They hatch only after ingestion by coprophagous beetles.
• In the beetles, larvae encyst on the tracheal tube. If the infected beetle is ingested by unsuitable host (i.e. paratenic host - like garden lizard, mice and domestic chicken) the larvae again encyst on oesophagus, mesentery and other visceral organs.
• Domestic chicken is considered to be important paratenic host in the transmission of infection to dog.
• Dog acquires infection by ingestion of either infected I/H or infected paratenic host.
• Following ingestion, larvae liberated in the stomach, then they penetrate stomach wall to reach the arteries and migrate to thoracic artery via coeliac artery in about 3 weeks of infection.
• After 3 months of infection, larvae migrate from thoracic aorta to oesophagal wall where they stimulate the granuloma development, within the granuloma they reach maturity in about 3 months.
• Prepatent period - 6 months.