Lungworms in Large Animals Flashcards
what are two main families of lungworms
- trichostrongyloidea
- metastrongyloidea
what is the lifecycle of trichostrongyloidea
direct life cycle
what species are trichostrongyloidea
Dictyocaulus species
what does trichostrongyloidea cause
parasitic bronchitis (husk)
pathogenic
what is the life cycle of metastrongyloidea
indirect
what are the metastrongyloidea species in pigs and what is the intermediate host
metastrongylus apri (earthworm intermediate host)
what are the metastrongyloidea species in sheep/goats and what is the intermediate host
muellerius capillaris –> snail/slug
protostrongylus rufescens –> snail
is metastrongyloidea pathogenic
not
what are the trichostrongyloidea lungworms in cattle
dictyocaulus viviparus
what are the trichostrongyloidea lungworms in horses and donkey
dictyocaulus arnfieldi
what are the trichostrongyloidea lungworms in sheep and goats
dictyocaulus filaria
what are the trichostrongyloidea lungworms in deer
dictyocaulus eckerti (capreolus)
what is the life cycle of dictyocaulus viviparus
what is present in the feces in the lifecycle in D.viviparus
L1 larvae not the eggs
dark food granules in intestine of L1
what do the D.viviparus adult worms look like
up to 8cm in length
slender
what occurs after infection of D.viviparus
strong immunity following infection but immune response can cause pathology
immunity boosted by natural challenge
what are the clinical signs of parasitic bronchitis (mild, moderate, severely affected)
- mildy affected animals (100 worms approx): intermittent cough
- moderately affected: coughing at rest, tachypnoe (<60), hyperpnoea (crackles posterior lung lobes)
- severely affected animals (1000 worms): harsh cough, tachypnoea (>80), dyspnoea, mouth breathing, pyrexia due to secondary bacterial infection, emphysema
what is the pathogenesis of parasitic bronchitis
- penetration phase: days 1-7 –> larvae migrating to lungs (no pathology)
- prepatent phasE: days 8-25 –> larvae migrating up through lungs
- patent phase: days 26-60 –> mature adults present in airways
- postpatent phase: days 61-90 –> adults expelled from airways (recovery)
what occurs during the prepatent phase (days 8-25) (5)
- L4 and young adults migrating up resp tree
- acute inflammatory response (monocytes and eosinophils)
- mucus/cellular plugs –> collapse of alveoli
- clinical signs first seen
5. heavy infection –> calves can die from day 15 onwards
what occurs during the patent phase (Days 26-60)
clinical signs worse
- lesions due to presence of worms in bronchi –> aspirated eggs/larvae
- profuse inflammatory exudate
- hyperplasia of bronchial epithelium
- over inflation of alveoli
- interstitial emphesema & edema
- lots of eosinophils
what occurs during the postpatent phase of parasitic bronchitis
most animals gradually recover, strong acquired immunity
some animals (up to 25%) —> clinical signs increase (often fatal) due to either alveolar epithelialization or bacterial infection (acute interstitial pneumonia)
what is occuring here
alveolar epithelialization in postpatent phase of parasitic bronchitis
what is reinfection syndrome in parasitic bronchitis
heavy challenge in immune animal (prev. infected or vaccinated)
IR kills larvae in lungs
coughing and slight tachypnoea –> mild syndrome
what is the diagnosis of reinfection syndrome
clinical signs
history
and response to treatment
how is parasitic bronchitis diagnosed
- clinical signs, time of year
- grazing/vaccination/athelmintic history
- L1 larvae present in feces (50-1000 L1/g, baermann technique) (not present during pre-patent phase)
how does ELISA diagnose parasitic bronchitis
detects antibody to adult and L3 antigens
reflects exposure to infection
available in UK through VLA
60% herds ELISA positive for lungworm
how is L1 detected in the feces in parasitic bronchitis
baermann apparatus
what is the epidemiology of bovine lungworm
temperate regions with high rainfall (N. Europe, N.E USA)
in UK usually july-sept/oct
which larvae can overwinter in bovine lungworm
L3 can overwinter
how many worms are needed to cause disease
small numbers
100-1000 worms
what are the optimal conditions for development of bovine lungworm
L1-L3 development rapid in warm and wet
where is bovine lungworm typically seen
1st season grazing calves
common in adult cattle
why is lung worm more common in adults
- susceptible to heavy challenge
- no prev history of lungworm or vaccination
- anthelminitic use in 1st and 2nd years (no immunity)
how is bovine lungworm prevented
- vaccination with irradiated L3 vaccine (2 doses of 1000 irradiated L3s)
vaccinate 1st season calves before turnout
very effective but not sterile immunity (dont mix unvaccinated)
how is bovine lungworm treated
anthelmintic drugs (use early to reduce pathology)
how are bovine lungworm midly infected animals treated
treat and move to clean pasture
how are severely affected animals with lungworm treated
house, hydration, NSAIDs, antibiotics if pyrexic
what is the lifecycle of dictyocaulus arnfieldi
similar to D.viviparus except eggs in feces
what is the PPP of dictyocaulus arnfieldi
2-4 months
reaches patency in donkeys and foals/yearlings in horse
doesn’t reach patency in adult horse
how are dictyocaulus arnfieldi
eggs or L1s in feces
close exam, harsh lung sounds
how is dictyocaulus arnfieldi diagnosed in horses
usually no eggs or L1s
clinical signs (chronic cough and tachyonoea)
grazing/anthelmintic history (co-grazing with donkeys)
response to anthelmintic treatment
tracheal wash –> eosinophils
what is the PPP of dictyocaulus filaria
5 weeks
what does dictyocaulus filaria cause
sporadic disease –> usually lambs/yearlings in autumn
what are the clinical signs dictyocaulus filaria
chronic cough/unthriftiness
nasal discharge
severe cases dyspnoea
how is dictyocaulus filaria diagnosed
L1 in feces
