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|species ='''''D. viviparus'''''
|species ='''''D. viviparus'''''
}}
}}
Also known as: '''''Bovine lungworm — Husk — Hoose - Dictyocaulosis — Parasitic Bronchitis'''''
Also known as: '''''Bovine lungworm — Husk — Hoose — Dictyocaulosis — Parasitic Bronchitis'''''
==Introduction==
==Introduction==
== Clinical Signs ==
== Clinical Signs ==
Signs include coughing and tachypnoea. In calves it can cause weight loss and even death in severe cases. In adult cattle, infection will tend to cause reduced milk yields and mild respiratory signs.
Signs include coughing and tachypnoea (depending on the number of worms) and an increased respiratory rate. In calves it can cause weight loss and even death in severe cases. In adult cattle, infection will tend to cause reduced milk yields and mild respiratory signs.
The penetration phase lasts one week and occurs when the larvae migrate to lungs. There are no clinical signs.
The '''penetration phase''' lasts one week and occurs when the larvae migrate to lungs. There are no clinical signs.
Then the prepatent phase lasts 1 - 3 weeks and is the development and migration of larvae leading to [[Bronchitis#Bronchiolitis|bronchiolitis]] and then eosinophilic exudate, causing the air passage to be blocked, resulting in alveolar collapse (distal to blockage). This is when clinical signs such as tachypnoea and coughing being to arise.
Then the '''prepatent phase''' lasts 1 - 3 weeks and is the development and migration of larvae leading to [[Bronchitis#Bronchiolitis|bronchiolitis]] and then eosinophilic exudate, causing the air passage to be blocked, resulting in alveolar collapse (distal to blockage). This is when clinical signs such as tachypnoea and coughing being to arise.
The patent phase then lasts around 4 - 8 weeks and the mature worms produce eggs during this period. Signs of [[Bronchitis|bronchitis]] are seen due to mature worms and [[Verminous Pneumonia|parasitic pneumonia]] is seen due to aspiration of eggs and larvae causing cellular infiltration of [[Neutrophils|neutrophils]], [[macrophages]] and giant cells.
The '''patent phase''' then lasts around 4 - 8 weeks and the mature worms produce eggs during this period. Signs of [[Bronchitis|bronchitis]] are seen due to mature worms and [[Verminous Pneumonia|parasitic pneumonia]] is seen due to aspiration of eggs and larvae causing cellular infiltration of [[Neutrophils|neutrophils]], [[macrophages]] and giant cells.
Finally, the postpatent phase, which lasts around 8 - 12 weeks is seen and here, the majority of worms are expelled. In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation, which may occur together with [[Pulmonary Emphysema|interstitial emphysema]] and [[Pulmonary Oedema|pulmonary oedema]], or secondary
Finally, the '''postpatent phase''', which lasts around 8 - 12 weeks is seen and here, the majority of worms are expelled. In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation, which may occur together with [[Pulmonary Emphysema|interstitial emphysema]] and [[Pulmonary Oedema|pulmonary oedema]], or secondary
bacterial infection.
bacterial infection.
Reinfection syndrome may occur if immune cattle are exposed to large numbers; only then will they show clinical signs.
Reinfection syndrome may occur if immune cattle are exposed to large numbers; only then will they show clinical signs.
==Diagnosis==
=== 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.
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===
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.
==Literature Search==
==Literature Search==