Internal parasite control in sheep Fewer worms More

Internal parasite control in sheep Fewer worms More dollars 1

Course aim Monitor and manage sheep worm populations to improve production, by: 1. Using worm egg counts to detect infestations early. 2. Becoming competent at the faecal egg count test. 3. Regular drench resistance tests. 4. Use of Worm. Boss in decision making. 2

Outline n Setting the scene n Types of internal parasites n Parasite damage to sheep n Introduction to Worm. Boss n Worm egg counting n Drench resistance 3

Setting the scene n Worms cost the Australian sheep industry $369 M/yr n This could increase to $700 M by 2010 n drench n more resistance production losses 4

Figure 1. National cost ($million) of major sheep health issues in Australia. (Source: Holmes et al. 2006) 5

Types of internal parasites Strongyles worms 2. Cestodes 3. Trematodes 1. or Round or or Tapeworms Liver flukes 6

Round worms (Strongyles) n Major cause of production losses in sheep n Summer dominant rainfall Barbers Pole n Black Scour n n Winter dominant rainfall Brown Stomach n Black Scour n Lung worms n 7

Round worms and site of infection Site Round worm scientific name Round worm common name Abomasum Haemonchus contortus Teladorsagia circumcincta Trichostrongylus axei Barbers Pole Brown Stomach Hair Small intestine Trichostrongylus colubriformis Trichostrongylus vitrinus Nematodirus spathiger Cooperia curticei Bunostomum trigonocephalum Strongyloides papillosus Black Scour Thin Necked Intestinal Small Intestinal Hook Worm Strongyloides Large intestine Trichuris ovis Oesophagostomum columbianum Oesophagostomum venulosum Chabertia ovina Whip Worm Nodule Worm Large Bowel Large Mouthed Bowel Lungs Dictyocaulus filaria Muellerius capillaries Large Lung Small Lung (Source: Cole 1980) 8

Life cycle of round worms (Source: Cole 1980) 9

Epidemiology n Temperature and moisture are critical for the survival of worm eggs and larvae n Round worms require avg. daily temp. of 10 o. C and 50% humidity (50 – 75 mm) to hatch n Except Barbers Pole – temp. above 15 o. C 10

Tape worms (Cestodes) n Most common/important species n Moniezia n live in intestines n no known ill effects n Echinococcus n Taenia 11

Liver flukes (Trematodes) n Only species in sheep is Fasciola hepatica n Complex life cycle and has a fresh water snail as an intermediate host n Live in bile ducts of liver 12

Parasite damage to sheep n Tissue damage n Competition for protein n Appetite reduction n Scouring n Anaemia (Barbers Pole) (Source: www. dpiw. tas. gov. au ) 13

Overall production effects Parasites will cause a reduction in: n fertility n milking ability n meat production n wool soundness n immunity 14

Introduction to Worm. Boss n Developed by Sheep CRC and AWI n www. wormboss. com. au n Recommendations: n monitor worm populations n regular drench resistance tests n use non-chemical management strategies n if unsure, seek professional advice 15

Exercise 1 – Using Worm. Boss n www. wormboss. com. au n Select “know your worms” n List major summer and winter rainfall worms n Select one worm from each rainfall group and list its scientific and common name, distribution, location in sheep and affects on sheep 16

Worm egg counting n Number of worm eggs in a sample of sheep dung - “eggs per gram” (epg) n Can’t distinguish between different round worm species “strongyle eggs” n More accurate than visual assessment 17

Worm egg counting n Useful to decide: n if treatment is necessary n if previous treatments were effective n assess level of worm contamination being put into paddocks n which sheep are worm resistant 18

View of worm eggs (Source: Worm. Boss website, Dr R Woodgate) 19

Worm egg typing n Larval culture and differentiation is required to differentiate between different worm species (Source: Worm. Boss website, Dr R Woodgate) 20

Exercise 2 – Worm Egg Count Test Aim of procedure n Materials n – including use and care of microscopes Method n Counting n Calculations n Interpreting results n 21

Use and care of microscopes n Start at lowest magnification n Rotate the focus wheel so you know which direction lowers/raises microscope n Focus using coarse focus first, then fine tune n Don’t allow microscope head to come in contact with slide n Rest eyes regularly n Always clean immediately after use 22

WEC test method n Weigh 2 g faeces from each sample into mixing bowl n Add 60 ml of saturated salt solution and mix n Pour through strainer to remove course material n Stir in a N-S E-W motion before allowing material to flow into pipette n Moisten counting chambers of slide n Fill the slide chambers from right to left and with the slide verandah facing away from operator n Allow about 1 min. between preparation and counting for eggs to float to top of slide 23

Counting the faecal eggs n See Egg Identification Sheet to identify different worm egg species n Place slide on microscope with verandah facing away from operator, use fine focus knob to focus slide n Begin counting using lines as a guide n For each sample, count and record number of eggs seen for each species 24

Egg identification (page 1) 1. Trichostrongylus (Black scour worm) 3. Coccidia 2. Haemonchus (Barbers Pole worm) 4. Moniezia (Tapeworm) The images on this page were sourced from: 1. www. stanford. edu/class/humbio 103/Para. Sites 2005/Trichostrongyliasis/agent. htm 2. www. sheepandgoat. com/Hair. Sheep. Workshop/parasitism. html 3. commons. wikimedia. org/wiki/Image: Coccidia. JPG 4. www. medata-systems. co. uk 25

Egg identification (page 2) 5. Trichuris (Whipworm) 7. Fasciola (Liver Fluke) 6. Nematodirus (Thin necked Intestinal worm) 9. Dictyocaulus (Lungworm) The images on this page were sourced from: 5. w 3. ufsm. br/parasitologia/arquivospagina/ovosdebovinos. htm 6. www. stanford. edu/class/humbio 103/Para. Sites 2005/Trichostrongyliasis/agent. htm 7. cal. vet. upenn. edu/projects/parasit 06/website/lab 6. htm 8. www. medicalvetonline. com. br/atlas. php 26

Calculation for FEC test Number of eggs/gram of faeces = number of eggs counted x total volume of mix (ml) volume of counting chamber (ml) x wt of faeces in mix 27

Interpretation of FEC test results www. wormboss. com. au n Click on “Ask the Boss” and read n Click on “Consult the Boss” and follow the prompts n. A report will be generated based on the information you enter 28

Drench resistance n Essential to know to be able to effectively manage worms n Occurs once worms can survive a dose of a drench that would have previously killed them n Measured by a Faecal Egg Count Reduction Test (FECRT) n Accepted industry definition = a reduction in worm egg count of less than 95% 29

Factors influencing development of drench resistance n Chemical group and persistency of the product involved n Frequency n Worm of treatments species involved n Environmental factors 30

How common is drench resistance? n Widespread, probably 90% or more of farms have a problem n Sheep worms have evolved resistance fairly quickly to each new drench group 31

Drench resistance testing n Essential to know the efficacy of drenches on your property n Assessed through a Faecal Egg Count Reduction Test (FECRT) n Should be conducted every 2 years 32

Exercise 3 – Setting up a FECRT 1. Select appropriate sheep − young, wormy and undrenched − at least 12 weeks old 2. Do a worm egg count − collect dung samples from min. 10 sheep − samples tested for enough worm species (min. 300 epg) 33

Setting up a FECRT 3. Decide drenches to test − seek professional advice − depends on previous test results and property drench history 4. Set up test groups − at least 15 sheep in each group plus one control (undrenched) group − ID each group 34

Setting up a FECRT 5. Drench each group − drench each group with correct drench − make sure: • • • 6. no cross contamination of drenches control group not drenched correct drenching technique used Return sheep to paddock together 35

Setting up a FECRT 7. Collect faecal samples for worm egg counting − 10 -14 days after initial treatment collect 10 fresh faecal samples from each group including the control group − obtain a larval culture and differentiation on samples from each group 36

Setting up a FECRT 8. Interpreting results − compare average no. of faecal eggs in each sheep group with that of the control − Fully effective drench = 95% worm egg reduction in relation to undrenched control group % efficacy = (control – treatment) / control x 100 37

www. wormboss. com. au 38