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Scenario
A wealthy retired businessman has decided to start an organic farm in Snowdonia, North Wales. He does not intend to get his own hands dirty and you are deputed to look after the health of his hundred strong flock of sheep. He stipulates that no antibiotics or man-made chemicals should be used at any time. What are the parasites you need to consider and what would you do to control and treat them?
Stocking Rate
Faecal egg counts
Introduction
Economical Aspects
•Uses faeces samples to determine level of parasite infection
•Can also identify species of parasite
•High egg count = high parasite burden
•Low egg count = low parasite burden
•Can indicate infection present before clinical signs appear
Macmaster slide used for faecal egg counts
Faeces samples and eggs present
Conclusion
Within the organic farming objective; grazing management and biological control are important components for future parasite control schemes in grazing livestock
Although man-made drugs are more reliable for control, resistance to worming groups is becoming an issue.
Holistic methods are currently not prone to the same resistance
Fencing
Grazing Management
Endoparasites to consider
with the highest prevalence
and pathogenicity in sheep
Livestock Rotation
References
=Rotating stock between pastures
Methods of control and Treatment
Abbott, D. K. A., Taylor, P. M. & Stubbings, L. A., 2009. Sustainable Worm Control Strategies for Sheep. 3rd ed. s.l.:SCOPS (Sustainable Control Of Parasites in Sheep).
Athanasiadou S, G. D. (2011). The use of chicory for parasite control in organic ewes and their lambs. pub med US National Library of Medicine National Institutes of Health , 299-307.
Black Welsh Mountain Sheep’s Association. 2010. The Breed. [online] Available at: http://www.blackwelshmountain.org.uk/breed. [Accessed on 5th March 2013]
Gunn, A. & Pitt, S. J., 2012. Parasitology. An Integrated Approach. s.l.:Wiley-Blackwell.
Kaufmann, J., 1996. Parasitic Infections of Domestic Anim (Sathor, 2012)als: A Diagnost (Sathor, 2012)ic Manual. s.l. (Sathor, 2012):ILRI (aka ILCA (Sathor, 2012) and ILRAD).
Knox, M. (2008). Effectiveness of copper oxide wire particles for Haemonchus contortus control in sheep. Australian Veterinary Journal , 224-227.
Mapes, C. J. & Coop, R. L., 1970. The interaction of infections of Haemonchus contortus and Nematodirus battus in lambs: I. The effect of massive infections of Haemonchus on subsequent infections of Nematodirus. Journal of Comparative Pathology, 80(1), p. 123–136.
Morris, M. C., 2000. Ethical Issues Associated With Sheep Fly Strike Research, Prevention, and Control. Journal of Agricultural and Environmental Ethics, 13(3-4), pp. 205-217.
Roberts, E. W., 1950. Studies on the life-cycle of Fasdoia hepatica (Linnaeus) and of its snail host, Limnaea (Galba) trnncatala (Müller), in the field and under controlled conditions in the laboratory.. Annals of Tropical Medicine and Parasitology , 44(2), pp. 187-206.
Sanders, A. B., How, S. J., Lloyd, D. H. & Hill, R., 1990. The effect of energy malnutrition in ruminants on experimental infection with dermatophilus congolensis. Journal of Comparative Pathology, 103(4), p. 361–368.
Sathor, T. (2012). Pros and Cons: A Debators Handbook . In T. Sather, Alternative Medicine (p. 280). Routledge.
Stear, M. J., Park, M. & Bishop, S. C., 1996. The Key Components of Resistance to Ostertagia circurmcincta in Lambs. Parasitology Today, 12(11), pp. 438 - 441.
Snowdonia Mountain Lamb. 2013. Order Forms. [online] Available at: http://www.snowdonia lamb.f9.co.uk/TopstripFrameset2.htm. [Accessed on 5th March 2013]
Stewart, D. F., 1950. Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp., and on the immunological reactions of sheep exposed to infestation. V. The nature of the 'self-cure' phenomenon.. Australian Journal of Agricultural Research, 4(1), pp. 100 - 117.
Taylor, S. M. & Pearson, G. R., 1979. Trichostrongylus vitrinus in sheep: II. The location of nematodes and associated pathological changes in the small intestine during clinical infection. Journal of Comparative Pathology, 89(3), p. 405–412.
Barger.I. 1997. Control by management. Veterinary Parasitology. 72,493-506
Larsen.M.1999. Biological control of helminths. International Journal for Parasitology. 29,139-146
Thamsborg.S,Roepstorff.A,Larsen.M. 1999. Integrated and biological control of parasites in organic and conventional production systems. Veterinary parasitology. 84,169-186
Torres-Acosta.J,Hoste.H. 2008. Alternative or improved methods to limit gastro-intestinal parasitism in grazing sheep and goats. Small Ruminant Research. 77,159-173
Waller.P.1993. Towards sustainable nematode parasite control of livestock. Veterinary Parasitology. 48,295-309
Waller.P,Thamsborg.S. 2004. Nematode control in ‘green’ ruminant production systems. Trends in Parasitology. 20:10
Waller.P. 2006. Sustainable nematode parasite control strategies for ruminant livestock by grazing management and biological control. Animal Feed Science and Technology. 126,277-289
Image References
Teladorsagia circumcincta (Previously Ostertagia)
– Brown Stomach worm
Slide 1 Intro - http://www.cashmeregoats.ca/user_files/images/Picture%20415.jpg & http://www.blackwelshmountain.co.uk/manor-ram.gif & http://www.johnstokesphotography.co.uk/Snowdonia.jpg
Slide 2 - Worm image - http://iranhelminthparasites.com/OVINE/o-circum1.jpg) & Egg image: http://www.viarural.com.ar/viarural.com.ar/ganaderia/ovinos/parasitos-internos/ostertagia-02.jpg)
Slide 3 - Worm image: http://2.bp.blogspot.com/-Wmv7vMkHmd4/T2A_bgTij-I/AAAAAAAAAAU/XWwXy_7iKqE/s1600/barberpoleworm.jpg & Egg image: http://www.apacapacas.com/parasites/para-site_files/53.jpgSlide 4 - Worm egg: http://www.rvc.ac.uk/review/parasitology/images/largeJPGs/Nematodirus-egg-_-p56.jpg & Worm: http://www.lightlivestockequipment.com/images/nematodirus-helvetianusegg.gif
Slide 5 - Worm & Egg: http://www.medical-enc.ru/18/images/trichostrongylus-colubriformis.jpg
Slide 6 - Fluke: http://4.bp.blogspot.com/_aoBb16P2vNQ/TIycQkU7fMI/AAAAAAAAACI/YtDWmVxQcxw/s320/fluke_med.jpg & Post mortem: http://curezone.com/upload/Liver_Flush/Forum_03/Fasciola_Hepatica.jpg & Egg: http://www.wadsworth.org/parasitology/Images/F.hep.jpg
Slide 7 - Mite: http://www.county-vets.co.uk/media/resources/psoroptes%20ovis.gif & Scab: http://www.fwi.co.uk/assets/getAsset.aspx?ItemID=5227831)
Slide 12 - Myasis Image - http://projects.exeter.ac.uk/meeg/blowflies
Slide 12 - Myasis Image - http://www.vetnext.com/search.php?s=aandoening&id=73253941305%20117
Biological controls: http://www.nablacognition.org/media/foto/5/img_5409.jpg
Faecal Egg counts: http://www.fao.org/wairdocs/ILRI/x5492E/x5492e18.jpg & http://jdflipflops.co.uk/resources/_wsb_414x242_macmasters+slide+2.JPG
Pros and Cons of Holistic Treatment
Genetic Selection
•Found within the abomasum and usually between 8-15mm in length
•T. circumcincta cause a decrease in gastrointestinal efficiency
•Causes – Anorexia, Diarrhoea, weight loss and death
•Severest effects are on lambs during their first summer
Myiasis (Fly Strike)
Teladorsagia circumcincta ova
(Sathor, 2012)
•Not species specific and results in adult flies laying eggs on the surface of warm wet skin.
•Larvae feed on tissue
•Infection attracts other flies to lay their eggs
•Very painful and uncomfortable
•Death can transpire very quickly due to infection
Teladorsagia circumcincta
mouth
parts
Effects of myiasis
Biological Control
Trichostrongylus spp.
(T. colubriformis & T. vitrinus)
– Black scour worm
Haemonchus contortus
– Barber’s Pole worm
Chicory - Cichorium intybus
•Both species reside within the small intestine and cause damage to the intestinal wall.
•Clinical Signs of infection: Diarrhoea, inappetence and rapid weight loss.
•Severe infections can lead to death
Psoroptes ovis - Sheep Scab
•The worms can be between 20-30mm in length
•Inhabit the abomasum during larval and adult stages, ingesting blood from the mucosa
•Symptoms – anaemia, tachycardia, dyspnoea, lethargy and poor milk production
•Severe infection can lead to death due to desanguination
•A mite that causes a form of allergy dermatitis, known as scab
•Mite lives on skin feeding on bacteria and secretions
•Initial signs include noticeable discomfort and scratching behaviour
•Can develop into severe form causing loss of wool and lesions
•Although not fatal, condition is uncomfortable and can increase incidence of myiasis
Trichostrongylus colubriformis adult
and ova
Hemonchus contortus ova
Hemonchus contortus
Adult
Effects of Psoroptes ovis
Psoroptes ovis adult
Fasciola hepatica (Liver Fluke)
•Requires intermediate host - Galba truncatula (Mud snail)
•G. truncatula requires muddy, acidic condition to survive. E.g. areas of poor drainage
•Conditions also allow liver fluke to flourish
•Damages the liver and bile ducts of sheep which it survives in.
•3 levels of infection: Acute, Sub-Acute and Chronic
•Symptoms vary with level of infection – Anaemia, dyspnoea, weight loss, diarrhoea, ascites and death
Fasicola hepatica life cycle
Nematodirus battus
Ectoparasites to consider
with the highest prevalence
or pathogenicity in sheep
Fasciola hepatica ova
Fasciola hepatica present within a sheep's liver following post mortem
•Pathogenic infection only in lambs
•Can reach 20mm in length and found in the duodenum
•Cause atrophy of the villi
•Symptoms: diarrhoea and dehydration
•Infection will lead to death or immunity as an adult
Nematodirus battus
adult male and
female
Nematodirus battus ova
Image obtained from CDC.gov