227.303 Parasitology; Nematode Ct1 A

Front 1

explain what is meant by the term 'infective stage'

Back 1

the stage in the life cycle of a nematode (or other parasite) capable of initiating infection in the host

Front 2

list 4 routes by which definitive hosts may be infected by nematodes

Back 2

ingestion, skin penetration, injection, transplacental migration

Front 3

describe a hepatic-tracheal migration route

Back 3

intestine (burrow into mucosa and carried passively via portal blood) to liver (via blood) to lungs - break out in alveoli, carried in mucus up trachea +/- some active migration to pharynx, swallowed into gastrointestinal tract (where parasite matures)

Front 4

Describe a lymphatic-pulmonary migration route

Back 4

intestine (burrow into mucosa and lymphatics, in lymph) to mesenteric lymph nodes (passively carried in lymph) to thoracic duct and vena cava (in blood passively carried) to heart and lungs (where parasite matures)

Front 5

describe migration post skin penetration

Back 5

Skin (secretes enzymes and actively burrows into blood vessels, carried passively in blood) to heart and lungs (breaks out in alveoli, carried passively in mucus flow +/- some active migration) to pharynx (swallowed) to gastrointestinal tract (where parasite matures)

Front 6

Given a nematode, which matures in the intestine, infects a foetus by crossing from the maternal to the foetal placental circulation, by what route would you expect the larvae to reach the intestine of the neonatal animal?

Back 6

placental blood --> foetal liver --> heart --> lungs --> traches --> digestive tract