Ruminant Trichostrongyles Flashcards
Economic losses
Pamb kid calve death Adult ill thrift and death Lower carcass value Poor growth rate Treatment and management costs
Teladorsagia circumcincta (brown stomach worm)
Sheep
Abomasal
Long and hair like
Dis seen in summer and autumn
Watery diarrhoea lost appetite and weight
Cause hyperplastic inflam of abomasal mucosa, repp gastric secr cells with non fxing cells
Hyperproteinaemia due to leakage across dam mucosa
Impaired abomasal fx assoc with pH alteration
Dev IC epi cells and mature emerge onto muc surf
Ostertagia ostertagi symptoms and pathogenesis
Larvae dev in and disrupt abomasal gastric glands adults emerge after 18d of infection
Sev path assoc with adult emergence
PH of abomasum rises as HCl secr cells replaced by indiff cells
Pepsin digestion of pro is inhib
Substantial albumin leakage through abomasal mucosa
Bact overgrowth in abomasum
Cause scour illthroft and suboptimal weight gains red milk yield
Haemonchus contortus
Sheep Abomasal Blood feeder Cause anaemia and hyperprotonaemia Usually seen in lambs in late summer Can occur in naive adults at any time of yr Can cause sub mand oedems Ascites Ill thrift Death Scour seldom present
Trichostrongylus vitrinus (black scour worm)
Prox small intest Just beliw muc layer White and hair like Burrow under mucosa causing villis atrophy so affect food digestion and adsorption Muc hypertrophy Pro leakage and electrolyte and mineral imbalance Dis during autumn and early winter Anotexia Dark scour Poor skel growth Poor woll quality Chronic ill thrift
Cooperia oncophora
Cattle
Mildly patjogenic
Assoc with inappetance and poor weight gain
Similar lifecycle to ostertagia
ML
Spec laxk of efficacy can be problem as just elim oo c have advantage and cause disease
Nematodirus battus
Sm intest Long white worm coiled around villi Catarrhal inflam of intestine Dis of young lambs 6-12wk old may-jun Cause acute onset diarrhoea lethargy abdom pain rapid weight loss dehydration sudden death
Nematode prod loss
Effect feed intake and usage so red growth rate
Hist parasite balance eg if previously unknown parasite encountered
Direct parasite effects
Indirect effects
Parasitic gastroenteritis most important in
Lambs in first grazing season
Naive ewes moved to contam pasture
Sheep with compr imm
Rams
Haemonchus lifecycle
Eggs shed in faeces
L1 and 3 dev in faeces
L3 onto herbage and exsheath in forestonach
L4 on muc surf of gut and feed on blood
Adult in lumen of gut feed on blood and mate and females lay eggs that are voided again
GIT nematode conditions
Hatching and dev of larvae in moist warm conditions min 7d in optimum
In optimal cond time between egg shedding and max L3 no on field is 3-6wk
Early larval stages easily killed by dessication
L3 can survive 6-12wk or longer on pasture and survive frosts
when cool damp conditions persist can survive for 12mnth (except haemonchus
T circumcincta pop dynamics in absence of control determined by
Pasture larval contam
Availability of L3
Build up of infection in sheep
There is an incr in FEC around parturition and early lactation
Comp between preg/lactation and inm resp
Ewes play ley role in teladorsagiosis epidemiology
Haemonchus teladorsag trichostrongylus dis risk for lambs assoc with
Overwintered L3 pop
Ewe faecal egg output
Autoinfection
Ostertagiosis patjigenesis
L3/4 in glands
Red parietal cells and incr undiff cells
Red HCl secr and cause leaky cell jctns
Pepsinogen gets into curc and plasma pros into GIT and red acidity cause pepsin not act from pepsinogen so pro not denatured and red bacteriostasis
Ostertagiosis epidemiology
L3 overwinter - die by mid summer cycled by calves early spring summer
Egg to L3 get faster as temp incr
L3 peak towards mid summer
Egg to L3 slows and stops kid autumn
Type 1 ostertagiosis dis
Dairy cattle
Overwintered L3 ingested early in grazing season dev into adults which are major source of subseq pasture larval contam
Rate of pasture larval contam highest mid summer as temp incre so most eggs deposited april-june all reach L3 stage
Ingestion of large L3 numbers causes clin type1 dis
Spring calving beef cattlenostertagiosis
Most overwintered L3 ingested and killed in imm cows, thise remain on pasture mainly die before calf old enough to ingest much herbage
Level of pasture contam in late summer and autumn is low
Calves succeptible to parasitic gastroent in 2nd grazing season
Autumn calving beef cattle
During first season similar to dairy calves
Type 2 ostertagiosis
Low autumn temp cause a ltd no of ingested L3 to become arreasted at early L4 in abomasal glands
Presence of eL4 usually asympt
Dis occur in late winter when arrested all simultaneously complete dev and emerge as adults
Risk incr with dry summer follwied by autumn rains or any pasture management that delays exposure of calves o high level L3 contam
Ostertagia imm
Acquired: unexposed suscept
Slow: not acquire until end of first season, maybe effect of suppresive anthelmithics?
Nematodiris battus
L3 dev in egg and can survive freezing for up to 2 yrs
Hatch and release only after period of cold follwoed by daily max tamp above 10 degrees
So eggs passed one yr hatch the following en masse may-jun
Acute dis when hatch coincides with presence of susceptible lambs not seen when hatch occurs befor lambs able to graze or after they are 3mnth old
Accum of infected pasture over several yrs
Nematodirus cycle
Eggs shed in faeces L1 and 2 dev in egg L3 onto herbage and exsheath in forestomach L4 on muc surf of gut Adults in lumen
Cattle lungworm
D viviparus
Adults in trachea and brinchi lay eggs cont L1 that hatch quickly are coughed up and swallowed amd passed in faeces
Dev to L3 can take min 5d in faeces, fastest with warm weather
L3 escape onto herbage is moisture dep
L3 ingested with grass and penetrate intestinal muc
Moult to L4 in mesenteric lymph nodes
Migrate to ventral parts of caudal
Ling lobes via blood and lymph
L4 enter albeoli moult to L5
Prepatent period 21-28d
Cattle lungworm overwintering
Some L3 overwinter on pasture and some adults or inhib L4 survive in carriers
In wet conditions fungi facilitate airborne L3 spread to other pastures and may be spread by earthworms with manure or wildlife
No of L3 on pasture incr in wet warm conditions
V small infevtious dose
Lungworm infection
1o infect: most dis between aug and oct Severely affected (mouth breathing) die Less affected self curr in several mnths Res milk yields Reinfect of exposed cattle following mass challenhe Following suppressive anthelmintic treatment for gastroent parasite control Lungworm common in 1.5-2.5yr old cattle Primary infection sometimes in older naive cattlr Post patent dis: alveolar epitheliasation Prolif of type 2 pneumoncytes Could be resp ti dead parasites
Sheep lungworm
D filaria
May be assoc with outbreaks of coughing and pneumonia in late autumn
Usually incidiental pm finding
Life cycle of M capillaris involve mollusc intermed, sheep infect when eat mollusc with herbage, adult worms in albeoli cause many subpleural nodules
P rufescens involve mollisc int. slender red worms in small bronchioles
D arnfueldi
Lifecycle similar to d viviparus Eggs infaecs Ppp 2-4mnth Reacg patency in donkeys and young horses no clin signs No patency in adult horses clin signs
What causes drop in live weight gain
Not parasite burden
It is the constant exposure to larvae
Management strategies
Avoidance
Treatment
Limit egg output
Sk finish lambs quickly before pasture burden becomes prod limiting
Only graze succep on safe pasture
Suppres pasture contam with anthelmitics
Clin paras gastroenteritis control
As long as no res to anthelmitics any can br used but lambs will fail to hit optimum weight gain when returned to contam pasture
So move to safe pastuee after dosage
If moxidectin used there is a meat wothdrawal period
Cattle gastroent control and problems
Aim to limit L3 exposure
Dairy calves and autumn borne beef: anthelmintic during 1st grazing season
Spring born beef: anthelmintic at first housing and during 2nd season
Calves may not acquire imm so may still be succeptible
Need to permit sufficient L3 exposure fo stim imm without loss of prod
May not control lungworm
Lungworm treatment
Anthelmintics
Anti inflam
Antibio
Lung worm control
Evasive can be ineffective as safe grazing often fails to prevent
Suppressive anthelmintics used for gastrointest can be effective but cattle seuscep in following grazing season
If rely on anthelm during 1st half of season may be suscept in 2nd half
Prob with spring borne calves
Additional strategic treatments often req
Vacc with huskvac when infection present vacc animals still contrib to pasture contam so entire herd must be vacc
