ESSENTIAL GUIDES ON SMALL RUMINANT PRODUCTION. Gastrointestinal parasites

PRESENTATION

BROCHURE

ESSENT AL GUIDES ON SMALL RUM NANT PRODUCTION

Gastro ntestinal parasites Elias Papadopoulos

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ESSENTIAL GUIDES ON SMALL RUMINANT PRODUCTION

Gastrointestinal parasites

ESSENT AL GUIDES ON SMALL RUM NANT PRODUCTION

Gastro ntestinal parasites Elias Papadopoulos

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This guide has been prepared and presented in the hope to become a useful tool for the diagnosis and control of the most common gastrointestinal parasitic diseases of sheep around the world. The book is intended to be used by those involved in addressing problems of sheep health focusing on gastrointestinal problems. It includes numerous images about parasites as well as the main lesions produced.

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TARGET AUDIENCE:

✱ Production animal vets. Sheep ✱ Animal production technicians ✱ Veterinary students FORMAT: 17 × 11 cm RETAIL PRICE NUMBER OF PAGES: 86 NUMBER OF IMAGES: 93 BINDING: Softcover, wire-o ISBN: 9788418020384 PUBLISHING DATE: January 2021

€29

Author ELIAS PAPADOPOULOS Professor and Head of the Laboratory of Parasitology and Parasitic Diseases at the School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki

KEY FEATURES:

➜ Written by a prestigious specialist in Parasitology. ➜ Contains numerous images of the main gastrointestinal parasites, as well as the principal clinical signs derived from each infection/infestation. ➜ Very convenient format, manageable in field conditions.

Presentation of the book This handbook has been prepared and presented in the hope to become a useful tool for the diagnosis and control of the most common gastrointestinal parasitic diseases of sheep around the world. The One Health approach has become important in view of the great significance of the zoonotic parasites and the role which veterinarians can play in their prevention. The book is intended to be used by those involved in addressing gastrointestinal problems of sheep health. It may be used by clinicians, laboratory diagnosticians and researchers alike, veterinarians or other professionals, as well as by students; it will also provide information to interested professional or hobby sheep farmers. The content comes from the book Atlas of Parasites in Sheep (Ed. Servet, Spain, 2016) and it is focused on gastrointestinal parasites. The book has a convenient format allowing to be handled in the farm. Consequently, it may become a useful tool for veterinarians to show farmers the importance of these diseases. It was avoided to provide an extensive overview, as in principle, this book has been prepared to become a supplement to other textbooks related to gastrointestinal sheep diseases. Each chapter is dedicated to a specific anatomic part of gastrointestinal system of sheep (i.e., oesophagus, rumen, abomasum, etc.). Each parasite is presented under the same format, including its latin and common name, taxonomy, location(s) within the host, geographical distribution, morphology, pathogenesis and clinical signs, diagnosis, control and public health.

Gastrointestinal parasites

The author Elias Papadopoulos

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Graduated (DVM) in 1988 from the Faculty of Veterinary Medicine, Aristotle University of Thessaloniki (Greece). Master in Veterinary Science (MSc) degree in Veterinary Parasitology in 1992 from the University of Liverpool (UK). PhD degree in 1997 from the Faculty of Veterinary Medicine, Aristotle University of Thessaloniki. He is Professor and Head of the Laboratory of Parasitology and Parasitic Diseases at the School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki. He has received training on parasitology in established European research centers and Universities. He has participated in several national and international research projects, published papers and delivered lectures in national and international scientific conferences.

Table of contents 1. Introduction 2. Oesophagus Gongylonema pulchrum (gullet worm)

3. Rumen/Reticulum Paramphistomum spp. (rumen fluke)

4. Abomasum Haemonchus contortus (barber’s pole worm) Teladorsagia spp.

5. Small intestine Cryptosporidium spp.

Eimeria spp.

Giardia spp.

Trichostrongylus spp.

Nematodirus spp.

Cooperia curticei

Bunostomum trigonocephalum Strongyloides papillosus Moniezia expansa/Moniezia benedeni

6. Large intestine Tetratrichomonas ovis Oesophagostomum spp.

Chabertia ovina Skrjabinema ovis (pinworm) Trichuris ovis (whipworm)

7. Liver Fasciola hepatica (liver fluke) Dicrocoelium dendriticum (small fluke) Cysticercus tenuicolis Hydatid cyst Linguatula serrata

References

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ESSENT AL GUIDES ON SMALL RUM NANT PRODUCTION

Gastro ntestinal parasites Elias Papadopoulos

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Abomasum

Gastrointestinal parasites

Haemonchus contortus (barber’s pole worm) The most common species is Haemonchus contortus, but other species have also been reported in sheep, as Haemonchus placei.

Morphology

Taxonomy: Class Nematoda, Superfamily Trichostrongyloidea.

Location: Abomasum.

Geographical distribution:

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Worldwide, particularly in The adult worms are very easily identified due to tropical and subtropical areas. their location, large size (2-3 cm) and the characteristic appearance of the white ovaries around the red (blood) filled intestine of the worm (fresh specimens) (Figs. 10-14).

Infective larvae have a medium size tail-sheath distance with narrow head (Figs. 13 and 14). Eggs are typical of the Trichostrongyloidea Superfamily (ellipsoidal or barrel-shaped and smooth surfaced with numerous blastomeres) (Figs. 15 and 16).

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ABOMASUM

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Figure 10. Haemonchus contortus body with ovaries winding spirally around intestine.

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Figure 11. Haemonchus contortus posterior end of female.

Figure 12. Haemonchus contortus head of female.

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Abomasum

Gastrointestinal parasites

Figure 15.

Second-stage larva of Haemonchus contortus: the larva’s body and the second-stage sheath (posterior end) may be observed.

Figure 13.

Haemonchus contortus cervical papillae (adult anterior end) (arrows).

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Figure 16.

Second-stage larva of Haemonchus contortus: the bolbous (anterior end) oesophagus may be observed (arrow).

Figure 14.

Haemonchus contortus adult female: vulval flap.

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ABOMASUM

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Figure 17. Trichostrongyle egg.

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Figure 18. Trichostrongyle eggs and larvae L1.

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Abomasum

Gastrointestinal parasites

Pathogenesis and clinical signs It is a blood-feeding parasite and, in large numbers, may cause haemorrhagic anaemia, weight loss, weakness and death. Each worm can obtain approximately 0.05 ml of blood per day from the mucosal vessels and therefore, in heavy parasitism, the haematocrit falls progressively (Fig. 19). Depending on the parasite burden, haemonchosis may be presented as hyperacute, acute or chronic form. The life cycle is direct and sheep become infected by ingesting the infective third-stage larvae (L3) with the herbage. Female worms are prolific egg layers contaminating the pasture. Eggs develop and L1 hatch in a week, depending on the temperature (in cooler environment this may take place after several weeks or months). Adult worms can move on the surface of the abomasum mucosa.

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Figure 19. Ewe with heavy gastrointestinal parasitism and low body condition score.

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ABOMASUM

Diagnosis and control It is based on faecal examination, particularly using a quantitative coprological method (i.e. the modified McMaster method), in order to estimate the number of eggs per gram of faeces. However, as in practise mixed infections with other trichostrongylids are common, a coproculture is necessary to be performed in order to identify the L3 of Haemonchus spp. Necropsy can give a clear picture of the worm burden (Fig. 20). PCR may be used for larvae identification, which is of limited use in the field practice at the moment.

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Figure 20. Haemonchus contortus adult worms in the abomasum mucosa.

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Abomasum

Gastrointestinal parasites

Sheep may be treated effectively with most of the anthelmintic groups, such as benzimidazoles, levamisole or macrocyclic lactones. It is important, additionally to adult worms, to remove the hypobiotic larvae. The use of anthelmintics should be combined with the pasture management. In milk-producing ewes, the residual withdrawal periods in milk should be kept into consideration, whereas in wool-producing animals this is not a case.

In most areas of the world, anthelmintic resistant strains of Haemonchus spp. have been developed reducing the effectiveness of treatments. In order to reduce the rate of the development of anthelmintic resistance, several strategies have been introduced to sheep industry, taking into consideration the balance of the worms coming in contact with the drugs or remain at pasture (in refugia). Most of them aim to the reduction of anthelmintic usage and the rotation of different drug classes (with different mode of action). Towards this end, strategic programmes are based on the Targeted Treatments (administration of anthelmintics to all the animals of the flock according, for example, to their reproduction phase, i.e. at tupping or lambing) or the Targeted Selected Treatments (administration of anthelmintics only to certain animals within the flock that are in need based on selection criteria, i.e. faecal egg counts, body condition score, milk yield and others).

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ABOMASUM

Particularly for haemonchosis, the Famacha system has been developed to enable the detection of infected sheep according to the colour of their mucous membranes, which reflects the level of anaemia due to parasitism. Recently, the use of vaccines has been introduced against Haemonchus spp. infection.

Public health: no reports.

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Teladorsagia SPP. The most important is Teladorsagia circumcincta, but other species also occur as Ostertagia trifurcata, Teladorsagia davtiani, etc.

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Taxonomy: Class Nematoda, Superfamily Trichostrongyloidea.

Location: Abomasum.

Geographical distribution: Worldwide.

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Abomasum

Gastrointestinal parasites

Morphology The adult worms are small (approximately male: 6-8 mm, and female: 8-10 mm), slender with a short buccal cavity (Figs. 21 and 22). Infective larvae (L3) have a short size tailsheath distance (Fig. 23). Females lay typical trichostrongyle eggs (Fig. 24). The species identification of the adults is based on the morphology of the bursa and spicules. a

b

c

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Figure 21. (a) Teladorsagia circumcincta female. Detail of the (b) head and (c) posterior end.

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ABOMASUM

a

b

c

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Figure 22. (a) Teladorsagia circumcincta male worm. Detail of the (b) head and (c) posterior end with bursa and spicules.

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Abomasum a

Gastrointestinal parasites b

c

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Figure 23. Teladorsagia circumcincta L3 (a). Anterior (b) and posterior (c) parts.

Figure 24. Teladorsagia circumcincta female worm with eggs.

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ABOMASUM

Pathogenesis and clinical signs

Public health: no reports.

Infected sheep show reduced appetite, weight loss and loss of plasma protein into the gastrointestinal tract. The life cycle is direct and sheep become infected by ingesting the infective L3 with the herbage. Ingested larvae enter the gastric glands and destroy them. In necropsy of heavily infected animals, the abomasal surface looks like morocco leather (Fig. 25).

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Diagnosis and control Diagnosis is based on the clinical signs, but confirmed with coprolog ical examinations and necropsy, as in haemonchosis or other trichostrongylids.

Control is based on the strategic use of effective anthelmintics, as described in haemonchosis.

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Figure 25. Characteristic lesions on abomasum mucosa due to infection with Teladorsagia circumcincta.

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