Nematodes Flashcards
Most important helminth group in domesticated animals is the phylum
Nematoda
Nematodes characteristics (5)
-non-segmented long, thin tube
-exoskeleton
-hydrostatic skeleton and muscle allow for locomotion
-separated sexes (mostly)
-straight gut, highly variable pharynx
The way to tell nematodes species a part is through their (3)
-mouth
-excretory ducts
-gonadal openings
Most nematodes are
Free living
During development, nematodes typically undergo ___ which forms a new ___
Four moults; cuticle
Some nematodes retain their old cuticle as a
Protective sheath
Basic life cycle of nematode:
Egg —> L1-L2 (free living or in intermediate host) —> L3 (infective, transitional stage) —> L4 (migration to definitive host) —> adult
Bursate nematodes includes the order
Strongylida
Strongylida (nematodes) are parasites of the
GIT or lungs
Male strongylida have a ___ which is used to ___
Bursa; grasp female for copulation
Four superfamilies of the order Strongylida (nematodes)
-Ancylostomatoidea (hookworms)
-Strongyloidea
-Trichostrongyloidea (hair worms)
-Metastrongyloidea
Which superfamily of Strongylida is found in small intestine of carnivores and ruminants
Ancylostomatoidea (hookworms)
Which Strongylida superfamily is found in the large intestine of horses and ruminants
Strongyloidea
Which Strongylida superfamily is found in the upper GIT (abomasum/stomach, small intestine) in herbivores and sometimes cats
Trichostrongyloidea
Which Strongylida superfamily is found in the lungs/pulmonary vasculature of cattle, cats, rats, and is of public health significance
Metastrongyloidea
Ancylostomatoidea (Strongylida < Nematode) have a ___ buccal capsule
Well developed and dorsally bent
Strongyloidea (Strongylida < Nematode) have a ___ buccal capsule
Well developed, straight
Trichostrongyloidea (Strongylida < Nematode) have a ___ buccal capsule and a well developed ___
Vestigial buccal capsule; well developed bursa
Metastrongyloidea (Strongylida < Nematode) have a ___ buccal capsule and bursa
Vestigial
Leaf crowns are usually present in the Strongylida superfamily ___
Strongyloidea
Teeth/cutting plates are found in the Strongylida superfamily ____
Ancylostomatoidea (hookworms)
Simple life cycle of Strongylida superfamily Trichostrongyloidea (7)
- Eggs in faeces
- L1 hatch in faeces after 24 hours
- Two mouths occur
- L3 escapes faeces and migrates horizontally on pasture in the presence of moisture, up a blade of grass
- Ingestion by host (sheep)
- L4 in small intestine
- Adult worms in GIT of host
L4 Trichostrongyles < Strongylida < Nematode enter
The mucosal lining of host where there is no further tissue migration
Only __% of bursate eggs will hatch in faeces
5%
Bursate larvae (L1) remain in ___ and feed on ___
Faeces; bacteria/moult
Bursate larvae (L3) can remain on pasture for
4-6 weeks
The fungi ___ is used by L3 Dicytocaulus to ___
Pilobolus; “hitch a ride” of 6 feet height and 8 feet long!
Bursate larvae can survive in faeces for
5-6 months
Cattle Trichostongyles (4)
-faeces stay moist for longer
-faeces surface area:volume small
-L3s survive dry pats best
-larvae climb 10cm up grass blade
Sheep Trichostrongyles (4)
-faeces surface area: volume large
-faeces evaporation higher than cattle
-eggs/L1 survive dry pats best
-larvae remain near base of grass
What is hypobiosis
A period of arrested development where the larvae within host undergo a period of rest
Ostentatious ostertagi (Small brown stomach worm) of cattle undergo ___ which means high infection rates can occur during ____
Hypobioses; later winter/spring, later summer/autumn
The Strongylida superfamily with the simplest life cycle is
Trichostrongyloidea
Trichostrongyloidea are (2)
-very small
-abundant in ruminants (especially lower GIT)
Clinical signs of Trichostrongyloidea infection (8)
-abomasitis
-anaemia
-oedema
-necrosis
-reduced weight gain
-chronic diarrhea
-emaciation
-death
Haemonchus reduces ___ and ___ in sheep
Blood packed cell volume; haemoglobin levels
The pre-patent period occurs
Before adult parasites release their eggs
Trichostrongylus spp. are the black scour worms of ___ and occur mostly in the ___ during ___
-sheep and cattle
-small intestine
-summer/winter rainfall
Haemonchus contortus affects ___. H.placei affects ___. This worm is also called ___
-sheep/goats
-cattle
-Barber’s Pole Worm
Barbers pole worm (Haemonchus) is found in the ___ during ___
Abomasum; summer rainfall
Ostertagia & Telodorsagia affect ___, are found in the ___ and occur during ___
-cattle and sheep
-abomasum
-winter rainfall and temperate climates
Cooperia is found in __ and affects the __
-cattle
-small intestine
Ancylostomatoidea are also called
Hookworms
Ancylostomatoidea have ___ on each plate
3 teeth
Dog and Cat hookworms (2)
Ancylostoma and Uncinaria
Hookworm of ruminants
Bunostomum
Ancylostoma caninum causes (2)
-anaemia
-ill thrift
Tracheal migration is a process where
A nematode in tissue migrates to the lungs and bursts into alveolar lumen where the worms are carried up the bronchial tree and swallowed
Two major Strongyloidea of horses
-Strongylus vulgaris (Large strongyles)
-Cyathostomes (small strongyles or red worms)
Large strongyles are ___ to anthelminthics during larval stage
Susceptible
Cyathostomes (small strongyles) are ___ to anthelminthics in larval stages
Not susceptible
Life cycle of Strongylus vulgaris (large strongyle) takes
6-7 months
S. vulgaris is the ___ of the Large Strongyles in horses and causes ___
-most pathogenic
-colic due to disruption of blood flow
True or False: S. vulgaris is common in horses
False. It is uncommon not due to anthelminthics
Which strongyle is NOT killed by anthelminthics during the tissue phase
Cyathostomes (small strongyles/red worms)
Life cycle of Cyathostomes (3)
-egg and L1-L3 in faeces/soil
-L3-L4 in wall of ileum and colon of horse
-L4-adult in lumen of colon
Metastrongyloidea are also called
Lungworms
Metastrongyloidea are found in
Lung tissues or blood vessels surrounding the lungs
An important species of Metastrongyloidea is
Angiostrongylus cantonensis (rat lung worm)
Angiostrongylus causes ___ in rats and ___ in accidental hosts
-lung infections
-brain lesions (eosinophilic meningitis)
