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Dictyocaulus viviparus


Mike Taylor

Andrew Forbes

Synonym(s): lung worm, lungworm, husk, hoose, verminous pneumonia, bronchitis




  • Phylum: Nematoda.
  • Class: Secernentea.
  • Superfamily: Trichostrongyloidea.

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Clinical Effects



  • Larvae may overwinter on pasture until late spring under certain climatic conditions.
  • Mild, wet conditions appear to be less favorable than colder winters with frost and snow.
  • Shifts in temperature to the optimum in conjunction with heavy rainfall can increase the numbers of L3 at pasture dramatically over a short period of time.


  • Female worms are ovoviviparous. Eggs containing first-stage larvae (L1) are coughed up, swallowed, and then hatch during passage through the digestive tract.
  • Under optimal conditions, the larvae develop to the L3 stage in 5-7 days, but may take longer depending on the environmental conditions.
  • Once developed the L3 leave the fecal pats to reach the herbage.
  • Airborne spread utilizing the fungus, Pilobolus may occur.
  • After ingestion, L3 penetrate the intestinal mucosa and pass to the mesenteric lymph nodes where they moult.
  • The L4 then travel via the lymph and blood to the lungs, and break out of the capillaries into the alveoli about 1 week after infection.
  • These migrate up the lungs and molt to L5, becoming mature adults between 3 and 4 weeks after infection.


  • Infection is via the ingestion of infective 3rd stage larvae (L3).
  • Usually only calves in their first grazing season are clinically affected as on farms where the disease is endemic older animals have a developed a solid immunity.
  • L3 may be dispersed by mechanical means such as vehicles, boots, animals’ feet and birds.
  • Heavy rain helps disintegrate the cowpats and disperse the larvae passively.
  • Airborne spread of larvae also occurs from field to field via spores of the Pilobolus fungus.

Pathological effects

  • Infection causes bronchitis and pneumonia.
  • During the prepatent phase, larval presence causes an alveolitis. Lungworm: the disease
  • This is followed by bronchiolitis and bronchitis as the larvae become immature adults and move up the bronchi.
  • Heavily infected animals may die from severe interstitial pneumonia and pulmonary edema.
  • In some animals, post patent parasitic bronchitis may develop, characterized by the development of a proliferative lesion in the lungs leading to emphysema and pulmonary edema develops and can lead to death.

Other Host Effects

  • Secondary bacterial infection may lead to pneumonia.
  • Exposure to infective larvae leads to the development of immunity to D. viviparus.
  • This immunity manifests as resistance to the establishment of larval infections but declines after 3 months in the absence of continued larval challenge.
  • The presence of a few adult worms in the lungs provides a long-lasting immunity with low levels of larval excretion.
  • Adult milking cows that have not been vaccinated or have not had sufficient exposure to lungworm larvae may experience a sudden drop in milk yield with subsequent coughing.
  • Host immunity can become overwhelmed by large numbers of migrating larvae in the lungs when cattle graze heavily infected pastures. This is known as “re-infection” husk.


Control via chemotherapies

  • All currently available anthelmintics are effective against D. viviparus.
  • Control can be achieved by dosing prophylactically using products with residual activities against lungworm at the start of the grazing season, or by the administration of rumen boluses.

Control via environment

  • Due to the unpredictability of disease, clean grazing strategies as used for control of parasitic gastrointestinal nematodes are less effective for lungworm control.


  • Vaccination offers the best method of control in areas where lungworm disease is endemic.
  • A live attenuated vaccine (Huskvac) is currently available in parts of Europe and is given orally to calves aged 8 weeks or more.
  • Two doses of vaccine are given at an interval of 4 weeks and vaccinated calves should be protected from challenge until 2 weeks after their second dose to allow a high level of immunity to develop.
  • Dairy calves or suckled calves can be vaccinated successfully at grass provided the vaccine is given prior to encountering a significant larval challenge.
  • All calves on a farm in an endemic area should be vaccinated and continued annually for each calf crops as vaccinated carrier animals may continue to excrete small numbers of larvae in their feces.
  • The vaccine should not be given to any calves showing signs of illness particularly signs of respiratory disease and vaccinated animals should not be mixed with unvaccinated animals.
  • It is important not administer a long acting anthelmintic or bolus, which may interfere with the development of immunity, until 14 days after the second dose of vaccine.
  • Fully protective immunity declines over a period of around 6 months, unless boosted by exposure to low-grade, natural infections.
  • A single dose of vaccine can be given as a ‘booster’ before turnout each year to older animals that have been previously vaccinated or have acquired natural immunity.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Gozdzik K, Engström A, Höglund J (2012) Optimization of in-house ELISA based on recombinant major sperm protein (rMSP) of Dictyocaulus viviparus for the detection of lungworm infection in cattle. Res Vet Sci 93, 813-818 PubMed.
  • Schunn A-M, Forbes A, Schnieder T & Strube C (2012) Validation of a Dictyocaulus viviparus MSP-ELISA and cut-off adjustment in a one-year longitudinal field study in dairy cattle herds. Vet Parasitol 189, 291-298 PubMed.
  • Holzhauer M, van Schaik G, Saatkamp H W & Ploeger H W (2011) Lungworm outbreaks in adult dairy cows: estimating economic losses and lessons to be learned. Vet Rec 169, 494 PubMed.
  • Fiedor C, Strube C, Forbes A, Buschbaum S, Klewer A-M, von Samson-Himmelstjerna G & Schnieder T (2009) Evaluation of a milk ELISA for the serodiagnosis of Dictyocaulus viviparus in dairy cows. Vet Parasitol 166, 255-261 PubMed.
  • Eysker M, Claessens E W, Lam T J G M, Moons M J & Pijpers A (1994) The prevalence of patent lungworm infections in herds of dairy cows in the Netherlands. Vet Parasitol 53, 263-267 PubMed.
  • Eysker M (1991) Direct measurement of dispersal of Dictyocaulus viviparus in sporangia of Pilobolus species. Res Vet Sci 50, 29-32 PubMed.
  • Wassall D A (1991) Use of an ELISA for serodiagnosis of parasitic bronchitis in cattle. Vet Rec 129, 353-355 PubMed.
  • Eysker M & van Miltenburg L (1988) Epidemiological patterns of gastrointestinal and lung helminth infections in grazing calves in the Netherlands. Vet Parasitol 41, 127-135 PubMed.
  • Jørgensen R J (1981) Studies on the lungworm Dictyocaulus viviparus (Bloch, 1792) and its epidemiology in young cattle with a description of an attempt to prevent parasitic bronchitis. Acta Veterinaria Scandinavica 76, 1–77.
  • Michael J K, Mackenzie A (1965) Duration of the acquired resistance of calves to infection with Dicytocaulus viviparus. Res Vet Sci 6, 344-395 PubMed.
  • Parker W H (1963) Lungworm infection in cattle-Control and Treatment. JAVMA 142, 743-750 PubMed.
  • Jarrett W F H, Jennings F W, McIntyre W L M, Mulligan W & Urquhart G M (1960) Immunological studies on Dictyocaulus viviparus infection Immunity produced by the administration of irradiated larvae. Immunology 3, 145-151 PubMed.
  • Michel J F (1959) Recent progress in the study of parasitic bronchitis. Journal of the Royal Agricultural Society of England 120, 28-44.
  • Jarrett W F H, McIntyre W L M & Urquhart G M (1957) Husk in Cattle. A review of a year’s work. Vet Rec 66, 665-692.
  • Jarrett W F H, McIntyre W I M, Jennings F W & Mulligan W (1957) The natural history of parasitic bronchitis with notes on prophylaxisand treatment. Vet Rec 69, 1329-1336.
  • Michel J F & Rose J H (1954) Some observations on the free living stages of the cattle lungworm in relation to their natural environment. J Comp Pathol Thera 64, 195-205 PubMed.
  • Soliman K N (1953) Migration route of Dictyocaulus viviparus and D. filaria infective larvae to the lungs. J Comp Pathol 63, 75-84 PubMed.

Other sources of information

  • Taylor M A, Coop R L & Wall R L (2016) Chapter 8 - Parasites of Cattle: Dictyocaulus viviparus. In: Veterinary Parasitology. 4th edn. John Wiley & Sons, UK. pp 380-382.
  • Van Dijk (2004) The epidemiology and control of dictyocaulosis in cattle. Cattle Practice 12 (2), 133-143.
  • David G (1999) Strategies for the control of parasitic bronchitis in cattle. In Practice 21, 62-68


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