Introduction to Nematodes Flashcards
Nematodes
Roundworms
Cestodes
Tapeworms
Trematodes
Flukes
Helminths
multicellular parasites
Nematodes- general characteristics
cylindrical in cross section separate sexes females produce eggs or LI
Direct life cycle
single definitive host- male and female worms develop in the definitive host
Indirect life cycle
involves a definitive host AND an intermediate host which is essential for the life cycle
Paratenic host
a host which serves to transport- not essential for the life cycle
Pre-patent period (PPP)
Period between infection and first appearance of eggs/larvae
Larval Migration
hepato-tracheal for example
from gut via portal system to the liver
via hepatic vein and posterior VC to heart
via pulmonary artery to lung
via bronchi/trachea/oesophagus to gut
Arrested larvel development
temporary cessation of development at a precise point in the life cycle
occurs in t.canis, ancyolostoma caninum, ostertagia ostertagi and cyathostomins
ALD/Hypobiosis
Hypobiotic=reduced metabolic rtate
resistant to many anthelmintics at this stage
helps avoid adverse environmental and immunological conditions
ALD important in epidemiology- ensures survival of the parasite during periods of adversity
Subsequent maturation can lead to disease
