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==Introduction==
==Introduction==
[[Image:Dictyocaulus viviparus.jpg|right|thumb|100px|<small><center>Dictyocaulus viviparus (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
[[Image:Dictyocaulus viviparus.jpg|right|thumb|200px|<small><center>Dictyocaulus viviparus (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
[[Image:Parasitic bronchitis.jpg|right|thumb|100px|<small><center>Parasitic bronchitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
[[Image:Parasitic bronchitis.jpg|right|thumb|200px|<small><center>Parasitic bronchitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
''Dictyocaulus viviparus'' is a bovine lungworm (a member of the '''[[Trichostrongyloidea]]'''). They are found in the trachea and larger bronchi and are responsible for parasitic bronchitis. There has been an increase in the incidence of husk in recent years; first season calves are particularly affected, although yearling and adult cattle may also succumb to the disease. Lungworm is responsible for reduced weight-gain and deaths in calves and yearlings and lowered milk-yield in dairy cows. A closely-related species is also responsible for one of the most important diseases of farmed deer. The parasite is of welfare importance if clinically affected animals are left untreated.
''Dictyocaulus viviparus'' is a bovine lungworm (a member of the '''[[Trichostrongyloidea]]'''). They are found in the trachea and larger bronchi and are responsible for parasitic bronchitis. There has been an increase in the incidence of husk in recent years; first season calves are particularly affected, although yearling and adult cattle may also succumb to the disease. Lungworm is responsible for reduced weight-gain and deaths in calves and yearlings and lowered milk-yield in dairy cows. A closely-related species is also responsible for one of the most important diseases of farmed deer. The parasite is of welfare importance if clinically affected animals are left untreated.
==Diagnosis==
==Diagnosis==
=== Calves===
=== Calves===
Diagnosis is based on the seasonal incidence, previous grazing history and clinical signs. Definitive diagnosis can be gained by performing a Baerman technique on a faecal sample to identify larvae. Samples need to be taken from both healthy and sick cattle as carrier animals may be important in the epidemiology of disease, e.g. in an endemic area 30% yearlings and 5% cows harbour patent infections, as do vaccinated animals. '''NOTE''': All lungworm-positive faecal samples are potentially significant.
Diagnosis is based on the seasonal incidence, previous grazing history and clinical signs. Definitive diagnosis can be gained by performing a Baerman technique on a faecal sample to identify larvae. Samples need to be taken from both healthy and sick cattle as carrier animals may be important in the epidemiology of disease, e.g. in an endemic area 30% yearlings and 5% cows harbour patent infections, as do vaccinated animals. '''NOTE''': All lungworm-positive faecal samples are potentially significant.
Post mortem examination can also be diagnostic; recovery of worms from lungs by the “Inderbitzen” or lung perfusion technique. Worms are flushed out of lungs by pumping water through pulmonary arteries. Water and worms passed out of trachea collected over sieve. '''NOTE''': Only 200-300 worms are required to cause clinical disease c.f. >40,000 ''[[Ostertagia]]''. Upon post mortem, one may also see pulmonary oedema and emphysema, which is thought to be caused due to a [[:Category:Hypersensitivity|hypersensitivity]] response to a massive invasion of lungworm larvae.
Post mortem examination can also be diagnostic; recovery of worms from lungs by the “Inderbitzen” or lung perfusion technique. Worms are flushed out of lungs by pumping water through pulmonary arteries. Water and worms passed out of trachea collected over sieve. '''NOTE''': Only 200-300 worms are required to cause clinical disease c.f. >40,000 ''[[Ostertagia]]''. Upon post mortem, one may also see pulmonary oedema and emphysema, which is thought to be caused due to a [[:Category:Hypersensitivity|hypersensitivity]] response to a massive invasion of lungworm larvae.
===Adult Cattle===
===Adult Cattle===
Diagnosis is again based on seasonal incidence, previous grazing history and clinical signs. Definitive diagnosis can be achieved by faecal examination using the Baerman technique to identiy larvae. Both healthy and sick cattle should be examined. Blood and Milk examination (ELISA) to look for antibodies can be used, but this has variable results (depending upon Ag used). Herd results are better than individual results in this case.<br>
Diagnosis is again based on seasonal incidence, previous grazing history and clinical signs. Definitive diagnosis can be achieved by faecal examination using the Baerman technique to identiy larvae. Both healthy and sick cattle should be examined. Blood and Milk examination (ELISA) to look for antibodies can be used, but this has variable results (depending upon Ag used). Herd results are better than individual results in this case.<br>
Grass examination for larvae around dung pats is useful. Response to anthelmintic treatment will provide a retrospective diagnosis.
Grass examination for larvae around dung pats is useful. Response to anthelmintic treatment will provide a retrospective diagnosis.
== Treatment and Control ==
If the animal is clinically affected, treatment with anthelmintic such as ivermectin can be used.
'''Vaccination – “Huskvac” (Intervet, original vaccine = “Dictol”)'''
Should be given to first-season calves, > 2months old, reared indoors. It is an attenuated oral vaccine (each dose, 1,000 X-irradiated ''Dictyocaulus viviparus'' L3). Vaccination is required at 6 weeks and again at 2 weeks pre-turnout. '''NOTE''': '''Never''' mix vaccinated and non-vaccinated animals. The vaccine is effective at preventing disease, although not 100% effective at preventing infection, i.e. even vaccinated calves may pass a few larvae → boost immunity in vaccinated calves, but could cause disease in non-vaccinated animals. A breakdown in protection can occur due to overwhelming challenge, improper storage or administration of vaccine, concurrent disease and mixing vaccinated and non-vaccinated calves. Therefore other control measures such as trying to keep a clean pasture and following instructions are very important.
'''Strategic anthelmintic programmes '''for preventing parasitic bronchitis can also be used. This will entail Ivermectin being administered at 3, 8 and 13 weeks post-turnout. '''NOTE''': Residual activity of 28 days against lungworm. There will be no anthelmintic cover if challenge encountered either early (0-3 weeks) or late (after 17 weeks) in the grazing season.
== Test yourself with the Cattle Nematode Flashcards ==
[[Cattle Nematode Flashcards|Cattle_Nematode Flashcards]]
==Literature Search==
==Literature Search==
[http://www.cabdirect.org/search.html?q=title%3A%28%22Dictyocaulus+viviparus%22%29 ''Dictyocaulus viviparus'' publications]
[http://www.cabdirect.org/search.html?q=title%3A%28%22Dictyocaulus+viviparus%22%29 ''Dictyocaulus viviparus'' publications]
[[Category:Expert_Review]]
== References ==
Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) '''Bovine Medicine''' (Second edition), ''Blackwell Publishing''
Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary''' (2nd Edition) ''Elsevier Science''
Divers, T.J. and Peek, S.F. (2008) '''Rebhun's diseases of dairy cattle''''' Elsevier Health Scieneces''
Fox, M and Jacobs, D. (2007) '''Parasitology Study Guide Part 2: Helminths''', ''Royal Veterinary College''
Merck & Co (2008) '''The Merck Veterinary Manual''' (Eighth Edition) ''Merial''
Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) '''Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses,''''' Elsevier Health Sciences''
[[Category:Respiratory Diseases - Cattle]]
[[Category:Bronchi and Bronchioles - Pathology]]
[[Category:Respiratory Parasitic Infections]]
[[Category:Respiratory Parasitic Infections]]
[[Category:Expert Review - Farm Animal]]
[[Category:Dictyocaulus]][[Category:Cattle_Nematodes]]
[[Category:Camelid_Nematodes]][[Category:Deer_Nematodes]]
[[Category:Camelid_Nematodes]][[Category:Deer_Nematodes]]