Bovis ISSN 2398-2993

Nematodirus spp

Synonym(s): Thread-necked worm

Contributor(s): Mike Taylor , Andrew Forbes




  • Phylum: nematoda.
  • Class: secernentea.
  • Superfamily: trichostrongyloidea.

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Clinical Effects



  • Infective larvae within the eggs overwinter on herbage, or in the soil, and usually hatch the following year, but may hatch in the autumn.


  • Female worms are oviparous. The large unembryonated eggs, containing 2-8 blastomeres, are passed in the feces.
  • Free-living development is almost unique in the trichostrongyloids in that development to the L3 takes place within the egg shell.
  • Species differences occur regarding the critical hatching requirements.
  • With Nematodirus helvetianus and N. spathiger, hatching of eggs occurs over a period of time, with larvae appearing on the pasture 2-3 months later.
  • N. battus eggs have more critical hatching requirements and require a prolonged period of chill followed by a mean day/night temperature >10°C, which can lead to a sudden, mass synchronised hatch of larvae.
  • The ingested L3 penetrate the mucosa of the small intestine and moult to the L4 stage.
  • After moulting to the L5 the parasites inhabit the lumen, sometimes superficially coiled around villi.
  • The prepatent period is generally 2-3 weeks.
  • Transmission is by ingestion of infective 3rd stage larvae from the pasture. Infection occurs mainly in calves in their first grazing season as older cattle have a developed immunity following exposure to the parasites.

Pathological effects

  • N. helvetianus is not generally considered to be pathogenic on its own.
  • Infections are generally low-grade and produce no obvious clinical manifestations.
  • Disease resulting from infection with N. battus has been reported in calves grazing pastures previously occupied by young lambs.

Other Host Effects

  • It has not been established if Nematodirus spp. may play a secondary role in the pathogenesis of PGE in cattle.


Control via chemotherapies

  • Disease due to Nematodirus infections alone is rarely seen and treatment usually aimed at general worm infections causing PGE in cattle may be effective.
  • However, Nematodirus is one of the dose-limiting species for some macrocyclic lactones so manufacturer’s data sheets should be consulted as there are differences in efficacy between injectable and pour-on products against adults and L4 stages.

Control via environment

  • Non-chemotherapeutic control measures outlined for other nematode worm infections will also help to control Nematodirus infections.


  • No vaccines are available.

Other countermeasures

  • Alternative countermeasures outlined for other nematode worm infections may also help to control Nematodirus infections.
  • The presence of N. battus can restrict the success of mixed sheep/cattle grazing systems as a means to help control parasitic gastroenteritis in either species of livestock.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Van Dijk J, De Louw M D E, Kalis L P A & Morgan E R (2009) Ultraviolet light increases mortality of nematode larvae and can explain patterns of larval availability at pasture. International Journal for Parasitology 39, 1151-1156 PubMed.
  • Van Dijk J & Morgan E R (2008) The influence of temperature on the development, hatching and survival of Nematodirus battus larvae. Parasitology 135, 269-283 PubMed.
  • Ballweber L R (2006) Endoparasite Control. Veterinary Clinics Food Animal Practice 22, 451–461.
  • Bairden K & Armour J (1987) Nematodirus battus infection in calves. Veterinary Record 121, 326-328 PubMed.
  • Gibbs H C (1980) Persistence in pasture of the infective larvae of nematodes parasitizing Maine dairy cattle. Am J Vet Res 141, 1694–5 PubMed.
  • Borgsteede F H M & Hendriks, J (1974) Identification of infective larvae of gastrointestinal nematodes in cattle. Tijdschr. Dlergeneesk 99, 103-113.
  • Gibson T E (1963) Experiments on the epidemiology of Nematodiriasis. Research in Veterinary Science 4, 258-268.

Other sources of information

  • Taylor M A, Coop R L & Wall R L (2016) Chapter 8 - Parasites of Cattle. In: Veterinary Parasitology. 4th edn. John Wiley & Sons, Chichester, West Sussex, UK. pp 380-382.
  • Taylor M (2015) Chapter 21, Applied Clinical Parasitology for Cattle Practitioners. In: Bovine Medicine. 3rd edn. Ed: Cockroft. John Wiley & Sons, Chichester, West Sussex, UK. pp 198-210.
  • Taylor M A (2004) Chapter 60, Antiparasitics. Ed: Andrews A H. Blackwell Science Ltd, 9600 Grassington Road, Oxford. pp 1019-1034.