Presentation on theme: "Internal Parasite Information"— Presentation transcript:
1Internal Parasite Information Anne Oakenful– Diagnostic & Analytical Services – Oct 09
2Internal ParasitesInternal parasites (worms and fluke) are estimated to be costing the Australian sheep industry $369m per year.This cost includes mortalities and production losses (reduced wool cut, stained wool, lowered staple strength), as well as the direct costs of control (mainly drenches and labour)
3Types of Internal Parasites 4 main groupsNematodes (roundworms)Trematodes (fluke)Cestodes (tapeworms)Protozoans (coccidia)
4Haemonchus spp. (Barber’s Pole worm) Nematodescommonly known as round worms eg:Haemonchus spp. (Barber’s Pole worm)Ostertagia circumcincta (Small Brown Stomach worm)Trichostrongylus spp (Black Scour worm).by far the most economically important group of internal parasites
5Life cycles…. Nematodes Most common internal parasite of domestic livestockNaturally carry low worm burdensAnimals need to be exposed to develop resistanceBecome a problem when numbers increase to cause production losses and or animal have other diseases
7Barber’s Pole Wormquite large worm (20 to 30mm) found in the abomasum.Adult females have a characteristic barbers pole appearance like red and white twisted wire. The male is smaller (around 15mm)sucks blood from the lining of the stomach which causes anaemia.adults suck around 0.05ml of blood per worm. A burden of 1000 worms may remove 50ml of blood (egg count would be around 5000epg)Sign of heavy infection includelack stamina, pale gums and conjunctiva, bottle-jaw, constipation.faecal worm egg counts are usually high before symptoms show (could be over 10,000 epg).a subclinical (no visible signs of worms) infestation can reduce weight gains by 30%, wool growth by 10% and milk production by 30%.Information sourced from Wormboss .com.au
8Brown Stomach wormoccurs in most sheep areas of Australia and is a major parasite in winter rainfall districts.small (10mm) red-brown worm just visible on the lining of the abomasum.very resilient, can survive freezing on the pasture and dry conditions.adults can arrested or inhibited for varying lengths of timeAdult female brown stomach worms lay eggs per day.damage the lining of the stomach as they mature from larvae to adult worms.heavy infections cause rapid loose of condition, profuse scours occasionally death.animals with fewer worms are unthrifty and daggy.Mixed infections of brown stomach worm and black scour worm are more lethal than infection with only one of the worms.Infection caused whitish nodules on the abomasum lining.production-loss occurs in the absence of obvious disease.a subclinical infestation can reduce weight gains by 35%, wool growth by 20% and milk production by 20%.Information sourced from Wormboss .com.au
9Black scour wormBlack scour worms occur in all sheep production districts of Australia.Adult female black scour worms lay 100 – 200 eggs per day.Black scour worms live in the first three metres of the small intestine of the sheep and cause damage to the lining of the gut.the larvae burrow into the wall of the small intestine and undergo a moult to become an immature worm.heavy infections cause rapid lose condition, scours, which may be black. The animal can dehydrate and may die.A subclinical infestation can reduce weight gains by 35%, wool growth by 10% and milk production by 20%.Damage to the intestinal wall leads to problems with nutrient absorbtion.Information sourced from Wormboss .com.au
10Trematodesinclude Fasciola hepatica (liver fluke) and Paramphistomes (stomach fluke).The most economically important fluke for livestock is liver fluke.This parasite causes substantial economic lost in certain geographical areas in Australia.
11Life cycle… Liver fluke Cost sheep and cattle industry around $50-80 million a yearReduced production and quality of woolreduced lambing percentagesPoor growth ratesReduced milk productionHave indirect life cycle that relies on freshwater snail (lymnaeid snail) as intermediate host.Infection only occurs where snail is found
12Life cycle… Liver fluke cont... Adult flukesin bile ductsMetacercariae ingestedFluke eggs in faecesMetacercariae on vegetationLymnaeid snail (intermediate host)MiracidiaCercariae leave snailsporocystcercariaerediae
14Protozoans Coccidia can affect all domestic animals. Most are host specific.Eimeria is the main coccidia infecting sheep and cattle.Cryptosporidium is another protozoan that can affect sheep and cattle.
15Life cycle… Coccida Generally host specific Cause disease by invading cells of intestinal wallCan be present in low numbers with no ill-effectAnimals develop immunity as they matureImmunity levels can drop if under stress (overcrowding, nutritional, weaning etc)
16Life cycle… Coccida cont… Common signs of infectionDiarrhoea (severe and containing blood)Rough coatPoor weight gainWeight lossWeaknessLower milk/meat/fibre production
17Life cycle… Coccida cont.. Coccidia multiply in intestine and form new oocysts (10 days approx.)24-48 hours in summerMay take weeks in winterOocysts in droppingsInfective oocysts
18Life cycle… Coccida cont.. In cattle infection called ‘black scours’Profuse, dark, foul smelly diarrhoeaAnimals infected byContaminated food, water or beddingLicking contaminated hair or udders
19Life cycle… Coccida cont.. Reduce infections by:Using feed and water troughsReduce overstocking, especially on damp pasturesAvoid holding animals in yards for long periodsAvoid mixing young and old stock together
20Faecal Egg CountsIs the most routinely performed test to estimate the worm population in an animal.Strongyle eggs float in saturated solutions of salt.If you use known quantities of samples and reagents, the number of parasite eggs per gram of faeces can be determined
21Collecting the sample Samples collected from : The ground - holding the animals in the corner of a paddock for 5-10 minutes and allowing them to drift awayDirectly from the rectum - insert gloved finger into rectum and gently move finger around until faeces is released. (should happen within 30 seconds)
22Wormtest kits Are a valuable tool for worm control Can be used to Monitor worm burdensDetermine if a drench is requireDetermine if the drench used was effective (drench resistance)Determine how “worming” a paddock isDetermine the species of worms present in the animal (if worm type conducted)Base management decision on results
23What happens in the labWeigh out known sample amount and add saturated salt solutionSubsample loaded into special chamber and then eggs are counted under the microscope.Results are multiplied by 40 to give the number of eggs per gram of faeces (epg)
24Identifying EggsStrongyles have a number of species that produce eggs of the same relative size.Need to hatch the eggs to identify larvae
26New Dipstick testAustralian Sheep Industry CRC have developed the dipstick test to detect when sheep should be treated to prevent Barber’s Pole worm disease (haemonchosis) outbreaksCan use the test in conjunction with faecal egg countsTest gives results before worm egg counts rise as immature worms are detected a week before they produce eggs
27Dipstick Test cont…The basis of the test is that Barber’s Pole worms are blood-sucking internal parasites. As they feed on the abomasum some blood passes through the digestive tract.The test detects haemoglobin (a product of blood breakdown) and changes colour according to the amount of blood in the sample
28Dipstick Stick cont…. Major benefits include: Results are available within 30 minutes on farmBurdens are detected before egg production beginsThe test is easily accessible and able to be kept on handThe test is reliable, accurate and inexpensive
29Dipstick Stick cont…In warmer months the dipstick test can be used weekly to predict risksTraining days for users will be conducted in coming monthsAt present the test is only been evaluated for sheepInterested graziers should contact their local Merial or Ancare Territory Manager or their local reseller for further information
30Egg Count Result Interpretation It is very difficult to give hard and fast rules on interpreting egg countsThere are so many variables to consider including:age of the animalsphysiological statushost speciesnutritional statusforecastingmanagement factorsthe worm mix
31Age of the animalAdult dry animals in good condition tolerate worms much better than young or poor animals.In the case of extensively grazed cattle, adults often require little or no drenching - except where liver fluke is a problem.Young animals, up to two years of age, are likely to need more frequent drenching
32Physiological statusLate pregnancy or lactating animals have a temporary relaxation of immunityit may be appropriate to consider drenching at lower egg counts than otherwise.
33Host speciesHost immunity will have a bearing on the interpretation of egg counts.Well-grown cattle and sheep over two years of age develop some immunity to worms.The immunity in cattle tends to be stronger than in sheep.Goats do not appear to develop a great deal of immunity, even when they reach adulthood.
34Nutritional statusWell-nourished animals quickly develop a strong immunity to wormswithstand a worm challenge better than poorer animalsmoving animals onto a better pasture, or hand feeding can, in some cases, have the same effect as drenching
35ForecastingA decision to drench or not, based on a certain egg count, may be influenced by how wormy pastures are likely to get in the coming weeks and months.plans for a move to cleaner, better pasture will impact on the decision to drench.
36The worm mixif barber’s pole worm is a common problem, egg counts are likely to be higher.of the three major sheep worms, barber’s pole worm has the highest egg output (around 10,000 eggs/day), followed by black scour worm ( eggs/day) and then small brown stomach worm (50-100/day).
37Guide to worm egg counts in sheep The department has a Primefact that gives guidelines for result interpretation.As a rough guide:0-200 epg –lowepg – moderate– highRemember toCheck egg counts in 4-6 weeks after significant rain, or before a ‘management event’ e.g. summer drench, pre-lambing, prior to yarding, or when there are signs consistent with parasitism.animals can get a heavy worm burden quickly before egg counts rise.
38Control Options for Internal Parasites When designing control program need to take into accountAvailable landRange of animals involvedLimiting restraints eg pastureEnvironmental conditions
39Control Options for Internal Parasites The 4 main components are:Strategic drench managementGrazing managementNutrition of the animalBreeding for worm resistant animals (in sheep)
40Strategic Drench Management Drenches divided into classes based on main active componentThere are broad and narrow spectrum drenchesNeed to rotate between classes to minimise development of resistance
41Strategic Drench Management cont… Broad spectrumEffective against wide range of parasite species & include:Benzimidazole (BZ) or ‘white’Levamisole (LEV) or “Clear”Macrocyclic lactone (ML) includes the avermectin (ivermectin/abamectin) and milbemycin (moxidectin) sub-groups.Naphthalophos (NAP) or OP (organophosphate), often used in combination with white and clear drenchesNarrow spectrumOnly effective against one or two parasite speciesClosantel which has sustained activity against susceptible barber’s pole worm, and strains of liver fluke.Triclabendazole which is highly effective against mature and immature stages of susceptible strains of liver fluke.
42Strategic Drench Management cont… Multi-combination drenchesRecent developments with 3 (eg TritonTM ) or 4 (Q-Drench TM) components.May be used where resistant worms are known to be present.New Drench on the BlockZolvix is a short acting broad spectrum drenchDeveloped by NovartisBelongs to a new drench group AADs (amino-acetonitrile derivatives)First new drench family since 1988Not yet available in Australia – may a few years before released here
43Strategic Drench Management cont… Get the most out of each drench by:Choose the correct drench for the jobGet the dose right (to heaviest in mob)Calibrate drenching equipmentDeliver the dose correctlyFasting before drenching (do not do this with clear or rametin based drenches)
44Strategic Drench Management cont… Effective drench kills 95% or more of worms.Important to know your drench resistance statusCan check byQuick Drench CheckDrench Test
45Strategic Drench Management cont… Drench Resistance in Sheep in NSWDrenchPrevalence of resistance (<95% drench efficacy)Benzimidazole (BZ)Approx. 90% of propertiesLevamisole (LEV)Combination (BZ/LEV)Approx 60-80% of propertiesMacrocyclic lactones (MLs, ‘mectins)Up to 80% of propertiesClosantelResistance in Haemonchus is common in northern NSW and QLD. Small number of resistant liver fluke in Australia.TriclabendazoleSmall number of resistant liver fluke in Australia.Naphthalophos (Rametin®, Combat®)One recorded case in Australia
46Strategic Drench Management cont… SheepStrategic worm programs designed for sheep producers in NSWDrenchPlanWormKillWestWormFarWestWormaim to reduce the number of drenches and worm larvae on the paddocks and to minimise production loss.Wormboss programAustralian Wool Innovation and the Sheep CRChas information on all aspects of sheep internal parasiteshas an interactive component “Ask the boss” to provide interactive advice.
47Grazing Management Prepare “low worm-risk” paddocks have relatively lower levels of infective larvae than other paddocks.use for most vulnerable animals i.e. weaners, pregnant/birthing animals.achieved by grazing with another animal speciesmost worms are host specific - ingestion by the non-preferred host results in the death of the larvae.Exception is barber's pole worm and stomach hair worm (T axei) which can infect both sheep and young cattle. Therefore, the use of adult cattle for cross grazing is preferred.
48Grazing Management cont… The length of time needed to graze paddock to help clean off infective larvae will vary from region to region and also depend on seasonal conditions.If running one type of animal - use older dry animals to graze the paddock (higher immunity).If the sheep are treated with a fully effective short acting drench, they can be used to "clean" paddocks for weaners (smart grazing) for the day period without fear of recontamination of the paddock.
49Grazing Management cont… Spelling a paddockmay be viable in some situations.the length of time needed will vary depending onseasonal conditionlength of pasturetype of worms present.short-term spelling is of little use for worm controlstudies have shown that spelling for more than 10 weeks in autumn/winter is needed to have a useful reduction in worm larvae numbers.
50Grazing Management cont… Cropped paddockssummer crops, such as lucerne, provide high nutrition to help the animal fight off worm infections.very good for young and susceptible stockhelp to break the worm cycle as generally have very low worm larvae contamination levels.But these paddocks can help to select for worm resistance.If the animals are drenched when going onto the paddock, the only worms left in the animals will be those resistant to the drench used. If animals left on paddock for more than 30 days any eggs/larvae deposited on the paddock will be a resistant strain.It is important to keep this in mind when making future management decisions involving the paddock.
51Grazing Management cont… Other strategies include:harrowing to break up the manureslashing when spelling pasture to expose larvae to sunlightremoving manure on a regular basis (useful in small paddocks)putting animals in to graze when pasture length is longer (larvae usually only travel up the first 10 cm of the grass blade).
52Nutritionhas an enormous impact on the immunity and ability to handle worms.a well-nourished animal will have better immunity than a poorly nourished one.strategic implementation has positive effect on immunity and worm control (particularly with protein supplements).supplementary feeding of certain minerals may increase the resistance of animals to worms.if using supplements remember to check toxicity levels of mixtures being usedalso monitor with regular worm egg counts to ensure that worm levels are under control
53Nutrition ResearchDepartment of Agriculture & Food WA – Dr Brown BesierWhen sheep fall below condition/fat score 2, live weights and wool production will suffer when they become infected with wormsAt condition score 3, the bulk of sheep will handle parasites very wellAt condition score 4, only a small percentage of sheep will suffer any production losses from a parasite infectionOnce young sheep and pregnant ewes were on a rising plane of nutrition, the animals become far more resilient to wormsThey are able to maintain relatively unchanged growth rates, wool growth and milk production despite having a worm infection
54Nutrition Research continued.. South Australia Research & Development Institute3 year study showed weaners that were supplementary fed in early summer to boost their nutritional level could have up to 50% lower faecal worm egg counts than unfed weanersThe high nutrition weaners produced 2-4kg more live weight & up to 250g more wool per head than unfed groupsThis was estimated to be worth around $6/hdAlso found improving the condition score of ewes in late pregnancy can halve faecal egg counts which was important to reduce worm burdens for new born lambs and help reduce the worm drench resistance cycle.
55Other interesting facts Research in the New England region found that as a rule of thumb after a month of daily temperatures of 30oC or more, about half of the larvae in the paddock will dieIf daily temperatures are around 15oC, it would take 2 months to kill the same number of larvaeStudies show that grazing paddocks with cattle six months prior to sheep grazing can reduce numbers of barber’s pole and black scour worms by as much as 98%, increase sheep annual weight gain by as much as 7kg, and lift greasy wool weight by around 0.7kg/head
56Breeding Worm Resistant Sheep Nemesis Program (CSIRO)found that resistance against the effects of worms in sheep is a heritable traitAnimals that are resistant to worms have the ability to:reduce the worm population by preventing development of infective larvae into adult wormsaccelerate rejection of adult worms from the animalreduce the egg-laying ability of female worms.it can take up to 10 years of using resistant rams to have an overall effect on flock immunity.A recent concept of developing resilience, i.e. the ability of an animal to be productive despite a sometimes heavy worm burden, is now being advocated by some parasite researchers