7. intro to parasites Flashcards
round worms are part of the phylum:
nemathelminthes
flat worms and flukes are part of the pylum:
platyhelminths
what is a prepatent period
the period between exposure to infection (ingestion of parasite) and when the parasite becomes detectable in feces or blood
what does patent mean
when the parasite is detetable in the feces or blood
what is an incubation period
the period between exposure to infection by a parasite and appearance of clinical signs
what is a paratenic host
- NOT an intermediate host.
- parasite does not develop any further and is only dormant
- for further development to occu the primary natural host must ingest the paratenic infected host to digest it
- this causes the release of dormant larvae and subsequent development to adult worm in the primary host
- life cycle in the paratenic host is referred to as quiexcence (not hypobiosis)
in what ways do parasites impact the agricultural economy
- reproductive performance
- wool production
- milk production
- carcass quality
- weight gain (inappetance or anorexia)
- death
- treatment and veterinary care
what is meant by visceral larva migrans
larvae migrate through visceral tissues
also applies for occular migrans and cutaneous migrans
how does lifecycle inform disease prediction
seasonal trends: egg shed in spring by adult worms infecting adult cattle/sheep will hatch and infect calves/lmbs. eggs which can overwinter can hatch and infect animals in the following spring
time of disease: after ingestion of pasture containing L3s they develop into adult worms in the gut in about 3 weeks. animals that graze on infected pasture can develop disease symtoms after 3 weeks of exposure
how can lifecycle inform diagnosis
GI parasitic diseases signs differ but there are general signs that can lead to diagnosis with sufficient accuracy. these signs can be determined by watching the behaviour/noting the appearance of the affected animal but often closer investigation is necessary
