Bovis ISSN 2398-2993

Haemonchus spp

Synonym(s): Hemonchosis, Barber’s Pole Worm

Contributor(s): Ash Phipps, Andrew Forbes, Vetstream Ltd

Introduction

Classification

Taxonomy

  • Phylum: nematoda.
  • Class: secernentea.
  • Subclass: rhabditia.
  • Family: trichostrongylidae.
  • Genus: haemonchus.
  • Species: H. placei, H. contortus.
Traditionally H. contortus was deemed to be the species that affected sheep and H. placei and H. similis the species that affected cattle. However, there is still some controversy as to whether H. contortus and H. placei should be considered as single species with strain adaptations for cattle and sheep, or whether they are in fact distinct species. From a clinician's point of view, this detail is probably irrelevant as the disease process, investigation and control strategies for each are identical.

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Clinical Effects

Epidemiology

Habitat

  • Adults inhabit the abomasum.
  • Eggs are passed in the feces.
  • L1 and L2 inhabit the feces.
  • L3 inhabit the feces and surrounding herbage.

Lifecycle

  • Prepatent period = approximately 28 days; can be shorter in the immunocompromised animals.
  • Direct lifecycle.
  • Adult worms produce eggs which are passed in the feces of cattle.
  • L1 hatch from the eggs within the feces.
  • L1 develop to L2 and L3 in the feces.
  • L3 are infective. 
  • Cattle ingest the L3 from the pasture.
  • The L3 larvae enter rumen and ex-sheath. 
  • The L3 undergo a further two molts in close proximity to the abomasal gastric glands.
Hypobiosis can occur in abomasal glands.
  • Adults occupy the mucosal surface of the abomasum.

Transmission

  • Ingestion of infective larval stage.

Pathological effects

  • Adult worms may consume 0.05 ml blood per day. The clinical disease observed will be dependent on the host ability to compensate for blood loss and protein loss. Main mechanism for clinical disease is anemia and hypoproteinemia. 
  • Acute presentation: severe anemia and/or sudden death.
  • Chronic presentation: poor growth, anorexia, anemia, bottle jaw and anasarca. 

Control

Control via animal

  • Immunity can develop post infection and hemonchosis in cattle is mainly seen in young animals. 
  • Animals over two years of age usually have reasonable immunity; but this immunity may be compromised in certain conditions, ie drought conditions may result in inadequate nutrition, which if combined with heavy parasite challenge (ie animals congregating around water hole, etc) may result in clinical disease in previously resistant animals. 

Control via chemotherapies

  • The anthelmintic of choice will be dependent on the following:
    • Targeted species (for treatment of mixed nematode infections).
    • Presence of anthelmintic resistance on the farm.
  • The products available will vary depending on the country and include some flukicides, eg Closantel Closantel, rafoxanide and nitroxynil, in addition to the macrolides, benzimadazoles and Levamisole Levamisole.
  • Not all products will be effective against arrested larvae.
Resistance to anthelmintics is a widespread issue for Haemonchus spp.

Control via environment

  • Avoid overstocking pens and paddocks. 

Vaccination

  • No commercial vaccine for Haemonchus spp is currently available. 
    • Trials have demonstrated potential for a vaccine to be developed to provide some protection against the nematode. 
    • Barbervax is commonly used in sheep and goats for protection against Haemonchus contortus.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Van Wyk J A & Mayhew E (2013) Morphological identification of parasitic nematode infective larvae of small ruminants and cattle: A practical lab guide. Onderstepoort J Vet Res 80 (1), 1-14 PubMed.
  • Bassetto C C et al (2011) Protection of calves against Haemonchus placei and Haemonchus contortus after immunization with gut membrane proteins from H. contortus. Parasite Immunol 33 (7), 377-381 PubMed.
  • Stevenson L A et al (1995) Differentation of Haemonchus placei from H. contortus (Nematoda: Trichostrongylidae) by the ribosomal DNA second interal transcribed spacer. Int J Parasitology 25 (4) 483-488 PubMed. Website: www.sciencedirect.com.
  • Fabiyi J P, Copeman D B & Hutchinson G W (1988) Abundance and survival of infective larvae of the cattle nematodes Cooperia punctata, Haemonchus placei and Oesophagostomum radiatum from faecal pats in a wet tropical climate. Aust Vet J 65 (8), 229-231 PubMed.

Other sources of information

  • Junquera P (2018) Haemonchus spp, Parasitic Round Worm of Cattle, Sheep, Goats and Swine. Biology, Prevention and Control. Haemonchus contortus, Haemonchus placei. Haemonchosis. Last accessed: 28 January 2018. Website: http://parasitipedia.net
  • Parkinson T J, Vermunt J J & Malmo J (2010) Diseases of Cattle in Australasia: A Comprehensive Textbook. New Zealand Veterinary Association Foundation for Continuing Education. pp 159, 729.
  • Anderson D E & Rings M (2008) Current Veterinary Therapy: Food Animal Practice. Elsevier Health Sciences. pp 80-81.
  • Radostits O M, Gay C C, Hinchcliff K W & Constable P D (2006) Veterinary Medicine: A textbook of the diseases of cattle, horses, sheep, pigs and goats. Elsevier Health Sciences. pp 1548-1551.
  • Foreyt W (2001) Veterinary Parasitology Reference Manual. 5th Edn. Blackwell Publishing Company, USA. pp 80.
  • Urquhart G, Armour A, Duncan J et al (1996) Veterinary Parasitology. 2nd Edn. Blackwell Publishing Company, USA. pp 19-22.
  • Parasitipedia.net. Website: https://parasitipedia.net.

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