Lecture 3 trichostrongylus

Series of Presentations on Nematodes from Veterinary Parasitology By Urquhart, Jenning

1. Trichostrongyloidea

2. Trichostrongylus
•Trichostrongylusalsocausesthe
gasrtointeritisinruminants.
•Onespecies,T.axeiisalsoresponsible
forgastritisinhorses.
•T.tenuisisresponsibleforsevereenteritis
ingamebirds.

3. Trichostrongylus
Hosts
Ruminants,horses,pigs,rabbitsandfowl.
Site
Smallintestine,exceptT.axeiandT.tenuis.
Distribution
Worldwide

4. Trichostrongylus
Species
T.axei abomasumofruminantsand
stomachofhorsesandpigs
T.colubrimormisruminanats
T.vitrinus sheepandgoats
T.capricola sheepandgoats
T.retortaeformisrabbits
T.tenuis smallintestineandcaeca
ofgamebirds

5. Identification
Gross
•The adults are small and hair like
•Less than 7.0 mm long
•Difficult to see with the naked eye

6. Identification
Microscopic
•Thewormshavenoobviousbuccalcapsule.
•Amostusefulcharacteristhedistinctexcretorynotch
intheoesophagealregion.
•Thespiculesarethichkandunbranchedandincase
ofT.axeiarealsounequalinlength.
•Infemalethetailisbluntlytaperedandthereisno
vulvalflap.

7. Life cycle
•The life cycle is direct and typical to other
strongyloides except the exsheathment of L
3of
intestinal species occurs in the abomasum.
•The development from egg to infective stage takes
1-2 weeks.
•The parasotic phase is non migratory.
•The prepatent periods in ruminants is 2-3 weeks.
•In hoses the prepatent period is of 25 days and in
game birds of 10 days only.

8. Pathogenesis
•AfteringestiontheL
3penetratebetween
theepithelialglandsofthemucosawith
formationoftunnelsbeneaththe
epithelium.
•After10-12daysofinfection,thetunnels
rupturestolibratetheyoungworms.
•Duetothisrupture,thereisconsiderable
hammorhageandoedemaandplasma
proteinsarelostintothulumenofthegut.

9. Pathogenesis
•Grosslythereisanentritisparticularlyin
theduodenum.
•Thevillibecomedistortedandflattened,
reducingtheareaavailableforabsorption
ofnutrientsandfluids.
•Inheavyinfectiondiarrhoeaoccurs.
•Diarroheaandplasmaproteinlossreults
inweightloss.

10. Pathogenesis
•In case of T.axei the changes induced in the
gastric mucosa are similar to those of Ostertagia
with an alteration in pH and increased
permeability of the mucosa.
•One difference is that the worms peneterte
between the glands rather than into the glands
as in Ostertagia.
•Coalescence of the nodular lesions often results
in plaques or ring like lesions.

11. Clinical signs
Heavyinfection
Rapidweightlossanddiarrohea
Lowinfection
Inappetanceandpoorgrowthrates
Softfaeces
Itisoftendifficulttodistinguishtheeffectsoflow
infectionfrommalnutrition

12. Diagnosis
•Clinicalsigns
•Seasonaloccurrenceofdisease
•Lesionsatpostmortemexamination
•Faecaleggcounts
•Faecalculturesarenecessaryforgneric
identificationofthelarvae.

13. Treatment and control
Like that of ostertagiosis

14. T. tenuisinfection
Ingamebirds,theheavyinfectionsproduceanacuteandfatal
haemmorhagictyphilitis.
Lighterinfectionsresultsinachronicsyndromecharacterized
byanaemiaandemaciation.
Treatment
Levamisoleindrinkingwater
Pensshouldbemovedregularlytopreventtheaccumulation
ofthelarvae.