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

Ingestion

THROUGH INGESTION

• The most common mode of transmission of parasites is through ingestion. The host may become infected by direct ingestion of an infective stage through contamination of food and water or by ingestion of an intermediate host or transport host containing infective stages.

Mode of infection through ingestion of parasite contaminated food

 Click here to view an animation

• For parasites with direct life cycles, the infective stages viz., egg containing the second larval stage (ascarids), cysts (Entamoeba and Giardia) and oocysts (coccidia) find their way into the feed and water of the host thereby gaining access to the host or the infective stages (third larval stage) may climb up the vegetations and wait for the host to ingest.

 Click here to view an animation

• For parasites with indirect life cycle, the host becomes infected by ingestion of an intermediate host or transport host containing infective stages.

 Click here to view an animation

• In certain parasites, the definitive hosts are infected through ingestion of infective stages (larval stages) in intermediate hosts (fish for Diphyllobothrium latum and crabs for Paragonimus sp) and through ingestion of raw or undercooked meat/organs/milk of intermediate hosts (Taenia solium, Echinococcus granulosus).

 Click here to view an animation