Cattle Parasitology PDF

Cattle parasitology 29/10/21 Overview • Life cycles • Seasonal disease risk • Diagnostic tools *CLINICAL PERSPECTIVE* • Control methods • Integrated approach • Drugs • Additional methods Gastrointestinal nematodes -UK Abomasum • Haemonchus placei (H. contortus) • Ostertagia ostertagi • Trichost...

Cattle parasitology 29/10/21 Overview • Life cycles • Seasonal disease risk • Diagnostic tools *CLINICAL PERSPECTIVE* • Control methods • Integrated approach • Drugs • Additional methods Gastrointestinal nematodes -UK Abomasum • Haemonchus placei (H. contortus) • Ostertagia ostertagi • Trichostrongylus axei Small intestine • Trichostrongylus colubriformis • Nematodirus helvetianus & N. spathiger • Cooperia oncophora, C. surnabada, C. pectinate, C. punctate Large intestine • Oesophagostomum radiatum • Bunostomum phlebotomum • Chabertia ovina • Trichuris spp. Parasitic Gastroenteritis (PGE) Pre-patent period? PGE: pathology & clinical presentation 1. Ostertagiosis: • Abomasal wall damage, • Raised pH of gastric juice from 2 up to ~7 • Poorer digestion bacterial overgrowth 2. Cooperia spp: • Damage to intestinal mucosa • Impaired absorption • Nutrients and water 3. Co-infection results in synergistic effect: • Diarrhoea and poor appetite • Poor appetite may account for most weight-loss 4. Consider grazing and worming history 5. Don’t forget about arrested development and type-II ostertagiosis PGE: animals affected? • Youngstock • First season dairy heifers • Autumn born suckler calves • Spring born suckler calves What is the difference? • Immunity acquired over 1-2 grazing seasons • Incomplete • Subclinical infections common in adults • Linked to reduced milk yield PGE: diagnosis • • • • Grazing history & signalment Clinical signs and seasonality Plasma pepsinogen- ostertagiosis Faecal egg counts • Standard McMaster’s salt flotation • Individual or composite samples • Not particularly useful for…? Type II ostertagiosis • Post mortem • Antibody ELISAs • Indicate exposure rather than infection • Can use milk samples • Potentially useful for adult dairy cows PGE: epidemiology Patent Subclinical Infection PGE Larva On Pasture Eggs on pasture January Turnout June Hypobiosis of O. ostertagi H O U S I N G December PGE: epidemiology Cold winter H O U S I N G Larva On Pasture Mild winter January Turnout June Dry summer Followed by rain December First season dairy calves H O U S I N G Larva On Pasture January Grass intakes Turnout June December Autumn born suckler calves H O U S I N G Larva On Pasture January Grass intakes Turnout June December Spring born suckler calves Grass intakes H O U S I N G Larva On Pasture June January Turnout December Lungworm: Dictyocaulus viviparus “Husk” “Hoose” Differences in epidemiology between gastrointestinal worms and lungworms : • Gut worms are ubiquitous • Lungworm infection not present on all farms • Gut worm larvae survive for months at pasture • Lungworm Survival on pasture is short • Gut worm larvae are already present on pasture at turnout • Progressive pasture infectivity builds over time • Egg output increases with worm burdens • Development of gut worm larvae on pastures takes weeks • After 6 weeks, pasture can be considered ‘clean’ again • Larvae not necessarily present at turnout • Most important source of infection year to year are carrier animals • Pasture infectivity build-up can be very fast Consistent, predictable annual disease pattern • Female lungworms produce larger numbers of offspring • Dispersal from faecal pats by Pilobolus fungi and rainfall Disease risk varies and is difficult to predict Lungworm: epidemiology • Not on all farms • History of disease? • Disease can be bought-in • Geographic variation of distribution • Associated with wet summers and rainfall • Liberation from faecal pats • Triggered dispersal of fungal spores • Similar seasonal pattern, but: • Carrier animals are important Lungworm: epidemiology PGE Lungworm Infected carrier Larvae On Pasture January H O U S I N G Turnout June December Lungworm: animals at risk? Depends on the farm • Typically 20% of animals are affected (5-30%) • History of disease: • Youngstock (1st and 2nd grazing season) • Bought-in cattle (from naïve herds) • No history of disease: • All cattle Lungworm: pathology & clinical presentation • Prepatent phase: L4 larvae in alveoli, migrate towards bronchi • Alveolitis, bronchiolitis, bronchitis • Patent phase (26 days+): Adult worms in larger airways, eggs and L1 larvae in the alveoli • Obstructive bronchitis • Aspiration pneumonia • Secondary bacterial infections • Pyrexia –associated with secondary bacterial infections • Animals may never fully recover from clinical disease • Ongoing losses in milk production ~£100/cow • Including treatment costs, fertility etc. ~£140/cow Lungworm: clinical signs >>>>>Mild >>>>>Moderate >>>>>Severe>>>>>> • Intermittent cough when exercised • Frequent cough at rest • Laboured breathing • Squeaks crackles on auscultation • • • • • • Severe tachypnoea Dyspnoea ‘Air Hunger Position’ Mouth breathing Deep harsh cough Salivation, anorexia • Death Lungworm: diagnosis • Signalment, history & clinical signs • Post-mortem • Oviviparous parasite- live L1 larvae passed in faeces • Patent infection >26 days • Baerman technique • >250um sieve/ gauze aperture • 24 hours • Antibody ELISAs • • • • Serum or milk samples Seroconversion >28 days Antibody titres persist 4-7 months post-infection Bulk milk tank sample analysis. • Positive results indicates >30% herd infected • Sampling strategy: • ~20% with patent infection • Exposure likely to be higher (sero-conversion) Liver fluke: Fasciola hepatica Liver fluke: epidemiology Summer snail infection Moo Winter snail infection Moo also Liver fluke: additional considerations Local on-farm conditions are equally important • Sheep and cattle both get fluke • Same genetic composition (no host adaption) • Co-grazing of sheep with cattle • Overwintering of sheep at pasture • Introduce resistance? • “Flukey” pastures? • Any area of wet or boggy ground • Standing water, rushes etc. give clues • Agri-environment schemes with wetland habitats • Which animals are at risk? • Little to no immunity • Immune modulation Liver fluke: pathology & clinical presentation Acute disease: • 2-6 weeks post-infection • Juvenile flukes migrating through liver parenchyma • Tissue damage and haemorrhage • Haemorrhage & anaemia • Uncommon in cattle- young calves with heavy challenge Chronic disease: • • • • 10-12 weeks+ post-infection Adult flukes within bile ducts Chronic anaemia, hypoalbuminaemia (“bottlejaw”) Weight-loss & poor BCS Sub-clinical infection: • Very common • Ongoing losses with growth/ milk-yield/ reduced fertility etc. Liver fluke: diagnosis • Signalment, history & clinical signs • Tricky in adult cattle/ subclinical infections • Serum biochemistry • Serum albumen, GLDH & GGT • Fluke egg sedimentation • Individual or composite samples • Patent infections only (12 weeks+) • Relatively low sensitivity • Copro-antigen ELISA • Theoretically more sensitive (4 weeks+) • Antibody ELISA • • • • 2-4 weeks post-infection Serum or milk samples BMT samples indicate >25% herd infected Exposure, not infection (consider treatment history) • Post mortem/Abattoir feedback Liver fluke: forecasting www.nadis.org.uk • Summer forecast 2020: • August – October 2019 & • May – June 2020 • Autumn forecast 2020: • May – October 2020 Treatment and control? Type II ostertagiosis PGE Type II ostertagiosis Lungworm Fasciolosis Larvae On Pasture January H O U S I N G Turnout June December Control • Plan strategy in advance • Integrated control plan • At-risk animals • Performance testing • Growth rates • Egg counts • Lungworm & Fluke • History of disease • Where on farm? • Pasture management • Move to “safe” pastures (e.g. aftermaths) later in season • Flukey pastures? Avoid grazing during risk periods • Lungworm • Vaccination available Limit reliance on anthelmintics – reduce selection for resistance Use of anthelmintics • Strategic • Keep pasture contamination low in the early part of the season • Practice set stocking • Can reduce treatment later into season • Overwintered larvae die off • Use safe grazing if available • Therapeutic • Treat in response to disease monitoring • Rotate grazing from early in the season • Housing • Opportunities for specific issues • Quarantine • Avoid buying-in disease/ resistance Anthelmintics • PGE & Lungworm • Group 1-BZs “white drenches” • Oral drenches: no residual activity • Bolus: prophylaxis for up to 140 days • Group 2-LVs “yellow drenches” • Oral drenches: no residual activity • Group 3-MLs “clear drenches” • Injectible & pour-on preparations • Varying residual activities- check datasheet PGE: Strategic dosing – Keep pasture contamination low Ivermectin pour-on 14d residual activity Doramectin injectable 5wk residual activity PGE: Therapeutic dosing • Monitor weight-gain and WECs • Good records essential • Signs of disease? • Consider grazing strategy through year • Optimise use of safe pastures and aftermaths • Difficult to do, but more sustainable • Treatments at housing are useful • Type II ostertagiosis • Group 3-MLs • Some group 1-BZs (check datasheet) Lungworm: Vaccination • Only recommended on farms with disease history • Irradiated L3 larvae (live vaccine) • • • • 1,000 larvae orally Calves >8 weeks old 2 doses, 4 weeks apart 2nd dose 2 weeks before turnout • Requires advanced planning • Subsequent natural exposure is essential for full immunity to develop… Turnout 2nd dose 1st dose Calves born before 18th February 4th February 7th January 12th November 17th March 3rd March 4th February 10th December 14th April 31st March 3rd March 7th January 19th May 5th May 7th April 11th February 16th June 2nd June 5th May 10th March 14th July 30th June 2nd June 7th April Natural challenge opportunities for lungworm?! Lungworm: clinical disease • Treat all animals in the affected group • Animals on same pasture at-risk • Not necessarily the whole herd • Move clinically affected animals to safe pastures or house (well ventilated building) • Treat with long-acting group 3-ML if not able to move • Check for secondary infections • Antibiotics and NSAIDs possibly indicated • Remember milk withdrawal in lactating animals Fluke: treatment • Informed by diagnosis • Varying activity of products • Juvenile vs. adult infection • Check datasheet! • Consider timing • Treat housed animals with adulticides • Reduce selection pressure on TCBZ • Consider milk-withdrawal for lactating animals • Treat during dry period Combination products CLOSENTEL IVERMECTIN TCBZ MOXIDECTIN CLORSULON IVERMECTIN Remember quarantine treatments • Avoid introduction of new parasites • Avoid introduction of drug resistance • COWS guidelines to reduce likelihood • Combination treatments • Holding animals off pastures Reducing resistance selection • COWS 5Rs • Check calibration/ application • Post-treatment egg count testing • • • • • Day 0 egg count Roundworms: 7-10 days (2-LV) Roundworms: 14-17 days (1-BZ sor 3-MLs) F. hepatica 21 days post treatment Ideally >95% reduction • Sometimes less due to Cooperia • ML-resistant O. ostertagi observed abroad • If unsure try alternative worming class • Quarantine treatments What else? • Coccidiosis • Cryptosporidium • Neospora caninum • Biting and nuisance flies • Ectoparasites • Lice • Mites • Ticks • Rumen fluke? Cryptosporidium • Young calves (14-21 days) • Environmental build-up • Oocysts persistent in the environment • Diarrhoea and dehydration • Co-infection with viral pathogens common • Diagnosis • History & clinical signs • Faecal smears: Ziehl-Nielsen staining • Pen-side antigen test strips • Zoonosis Cryptosporidium: treatment and control • Good hygiene practice • Disinfection of pens & feeding equipment • Reduce stocking density • Opportunities for transmission • Halofuginone • Prophylaxis 24-48hrs of age • Reduces symptoms in clinical cases • Supportive treatment • IVFT Coccidiosis • Young calves (ages) • Eimeria zuernii & E. bovis most important • Replicate in caecum & colon • Environmental build-up • Housed AND grazing animals • 3-4 weeks post-weaning • Pre-patent period ~17 days • Sporulation time 2-4 days • Bloody dysentery and tenesmus • Chronic wasting/ poor appetite • Diagnosis: • History and clinical signs • Post mortem and histopathology • Oocysts (Wet smears or McMaster) • Check species ID Coccidiosis: treatment and control • Reduce environmental contamination • All-in all-out with cleaning and disinfection • Prophylaxis • Decoquinate feed supplement • Toltrazuril & Diclazuril • Treatment • Toltrazuril & Diclazuril • Supportive treatments may be necessary Neosporosis • Diagnosed ~25% of abortion cases (VIDA 2015) • Dogs are definitive host • Faeco-oral transmission to cattle • Biosecurity issue • In cattle: • Life-long infection • Recrudescence during pregnancy • Waxing and waning of antibody titres • Late embryonic loss & abortions • 3-9 months • Persistently infected calf (vertical transmission) N. caninum: Prevention/Control • Keep a closed herd and do not buy in any replacement stock • Dispose of cattle tissues left over from a calving, or aborted foetuses, in a safe and timely manner. • Prevent dogs from having access to calving areas or parts of the farm where pregnant cattle are kept. • Deny dogs access to areas where cattle feed is kept or fields that are used for grazing to prevent dog faeces. • Signage on public footpaths. • Serum antibody testing • • • • Ideally 12-4 weeks pre-calving (recrudescence) Serum sampling of calves pre-colostrum for evidence of vertical transmission If positive, do not breed from mother or calf again False negatives may occur Biting & nuisance flies • Fly strike in cattle very rare • Worry and avoidance behaviour • Active May-October • Disease vectors • Hydrotea irritans: summer mastitis • New forest eye: Muscidae • Cullicoides: BTV, Schmallenberg Biting & nuisance flies: control • Spot-on/ pour-on synthetic pyrethroids • Limit length of activity • Tail bands/ ear tags • Pasture management & breeding habitat • Topping • Stocking density • Mitigation of risk • Stockholm tar • Bluetongue vaccination Ectoparasites • Lice • Chewing –Bovicola • Sucking –Linognathus • Mites • Chorioptes bovis • Psoroptes bovis • Sarcoptes scabei Common over winter in housed animals • Ticks • Ixodes ricinus • Vectors for babesiosis & anaplasmosis, louping-ill etc. Ectoparasites: diagnosis, treatment & control • Lesion patterns, microscopy, skin scrapes etc. • Synthetic pyrethroids • Pour-on/ spot-on • Lice • Group 3-MLs • Pour-on/ injectible • Lice & mites (& eL4 O. ostertagi) • Pour-ons for chewing lice • Injectibles for sucking lice Tick control? • Nothing carrying a licence • Possibly some group 3-MLs and synthetic pyrethroids • Improved pasture and clearance of scrub • Reduce other tick host species contact eg. deer • Be aware of TBD prevalence in the area • B. divergens southwest England & central Ireland • • • • Pyrexia & anaemia with “hammer” heart Pipe stem diarrhoea followed by constipation Port coloured urine “redwater” Treat with imidocarb Rumen fluke: Calicophoron daubneyi • Same snail host as F. hepatica • Galba truncatula • Similar epidemiology • Increasingly common • Particularly Ireland, but also in the UK too • Pathogenic? • Adults- Probably not. Live on rumen mucosa • Juveniles- Some case reports in youngstock • With massive infection • Duodenitis, haemorrhage, diarrhoea, death • Eggs detected by faecal sedimentation • “Clear” fluke eggs Fluke: treatment • Informed by diagnosis • Varying activity of products • Juvenile vs. adult infection • Check datasheet! • Consider timing • Treat housed animals with adulticides • Reduce selection pressure on TCBZ • Consider milk-withdrawal for lactating animals • Rumen fluke? • Oxyclozanide only licenced product Resources www.cattleparasites.org –COWS group sustainable worm use www.nadis.org.uk –Parasite forecasting www.noahcompendium.co.uk –Datasheets