Other Gastro Intestinal Nematodes Flashcards
What do you mean by “other”?
- The Major pathogenic species of nematodes contributing to PGE in UK is Teladorsagia circumcincta
HOWEVER there are 2 other species contribute to PGE – capable of causing PGE in own right and also contribute to overall infection
What are the other gastro intestinal nematodes?
- Trichostrongylus spp (major in Australia)
* Cooperia spp (not deemed to be anywhere as pathogenic as the other two. But contributes in PGE)
Broadly describe the morphology of Trichostrongylus species
- Small (5mm)
- Diagnostic feature = excretory notch
- Trichostrongylus axei - abomasum
- OTher species Trichostrongylus - SI (sheep and cattle)
(T. vitrinus & T. colubriformis)
Clinical sign denoting Trichostrongylus species is controbuting to PGE
Black Scour
List the worms down in abomasum according to size. B to S
- Haemoncus contortus - biggest
- Telodorsagia
- Trichostrongylus – smallest. Usually 5 mm
If found Trichostrongylus species which would it be if found in
a) SI
b) abomasum
a) SI = T species
b) Abomasum = T axei
How do you tell trichostrongylus species males and females apart?
- F half a cm bigger
- TAIL END
F - Vulval flap = ABSENT. Blind end, no special structure present
M - BURSA with finger like projections of the cuticle and short spicules
How many eggs are seen in trichostrongylus species female uterus
Fewer than 12
Trichostrongyle life cycle
- Found in abomasum or SI
- Female produce egg
- Eggs out in faeces onto pasture
- Faeces are released as L3
- L3 ingested become L4 in abomasum (T axeii) or SI (other T species)
- PPP (time between ingestion and eggs passed) is 3 weeks
- Very depended on TEMP (egg to L3)
How long is PPP
3 weeks
Pathogenesis and disease of T species
- When predominant cause of PGE - More typically in September vs Teledorsagia C – august to September
- Larvae (L4, L5) develop deep in mucosa
- Sub-epithelial tunnels
- Villous atrophy
- Haemorrhage – gives clinical sign of black scour (unlike T, circumcinsta)
- Oedema
- Diarrhoea
Clinical signs
- Black scour
- Weight loss/poor weight gain amongst flock of lambs
- Poor skeletal growth (post mortum) due to presence of large numbers of parasites
- Traditionally an autumn disease of store lambs buuuut some years we have not started seeing occurring earlier, especially after a mild winter
Cooperia species
• Species that affect both cattle and sheep
• Component of PGE (present at time PGE occurs, not necessarily the predominant species causing PGE)
• Very common
• Less susceptible to anthelmintics than other trichostrongyle nematodes (dose defining species)
o Cooperia found to be the species killed at only higher dosage. Whole concept the idea that multiple infections present so any drug must be able to target multiple species at the same time
Morphology of cooperia adult worm
- Adult worm 1cm +
• ‘watch spring’ worm – tight coil is v distinctive, pinky colour
• cephalic vesicle – head end of worm has transparent extension of cuticle, like narrow bubble. Inflation at head end but extends down a bit. SMALL INTESTINE
• male has short, stumpy spicules tail end, bottom LHS
Pathogenesis of cooperia
- Generally considered to be a mild pathogen – not particularly pathogenic
- Can affect weight gain
- Heavy infections lead to catarrhal enteritis, villous atrophy in SI, oedema of intestinal mucosa
- Important to know it will be present every year, will have a mixture of species
