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[[Image:Dictyocaulus arnfieldi.jpg|thumb|right|150px|''Dictyocaulus arnfieldi'' from horse faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
[[Image:Dictyocaulus arnfieldi.jpg|thumb|right|150px|''Dictyocaulus arnfieldi'' from horse faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
== General Appearance ==
== General Appearance ==
*Bursate.
*Bursate
*Typically, look like pieces of string (some, though, are very small).
*Typically, look like pieces of string (some, though, are very small)
*Each species has a predilection site at some level in the respiratory tract (e.g. trachea and bronchi, bronchioles, alveolae and parenchyma) or associated blood vessels.
*Each species has a predilection site at some level in the respiratory tract (e.g. trachea and bronchi, bronchioles, alveolae and parenchyma) or associated blood vessels
== General Life-Cycle ==
== General Life-Cycle ==
*The typical life-cycle is indirect, with a molluscan intermediate host.
*The typical life-cycle is indirect, with a molluscan intermediate host
*There are some exceptions (e.g. ''Metastrongylus'' in pigs, which use earthworms as intermediate hosts, and ''Filaroides'' in dogs, which has a direct life-cycle).
*There are some exceptions (e.g. ''Metastrongylus'' in pigs, which use earthworms as intermediate hosts, and ''Filaroides'' in dogs, which has a direct life-cycle)
*Adult female lungworms → eggs → wafted up trachea by epithelial cilia → throat → swallowed → pass through alimentary tract.
*Adult female lungworms → eggs → wafted up trachea by epithelial cilia → throat → swallowed → pass through alimentary tract
*Eggs typically hatch en route → L1 in faeces.
*Eggs typically hatch en route → L1 in faeces
*L1 has a wavy tail and some soecies also have a sub-terminal peg.
*L1 has a wavy tail and some species also have a sub-terminal peg
*L1 eaten by mollusc intermediate host → infetive L3.
*L1 eaten by mollusc intermediate host → infective L3
*If small mammals or birds eat the mollusc intermediate host, the L3 of some species (e.g. ''Aelurostrongylus'', the cat lungworm) invade the tissues and utilise the animal as a paratenic host.
*If small mammals or birds eat the mollusc intermediate host, the L3 of some species (e.g. ''Aelurostrongylus'', the cat lungworm) invade the tissues and utilise the animal as a paratenic host
*The final host is infected by ingesting an intermediate or paratenic host carrying the L3.
*The final host is infected by ingesting an intermediate or paratenic host carrying the L3
*The L3 migrates from the intestine → mesenteric lymph nodes → blood → lungs.
*The L3 migrate from the intestine → mesenteric lymph nodes → blood → lungs
*Prepatent period varies between species.
*Prepatent period varies between species
NOTE: the most pathogenic worms in the lungs of ruminants and equines belong to the genus ''Dictyocaulus''. These look like typical metastrongyloid lungworms, but molecular studies have confirmed that they are related to the Trichostrongyloidea (a case of convergent evolution). This explains why their life cycle is so different from the others.
[[Angiostrongylidae]]
[[Angiostrongylidae]]
*''Aelurostrongylus abstrussus'' in [[Respiratory Parasitic Infections - Pathology#Aelurostrongylus abstrussus|lung parenchyma and small bronchioles]] of cats
*''Aelurostrongylus abstrussus'' in [[Respiratory Parasitic Infections - Pathology#Aelurostrongylus abstrussus|lung parenchyma and small bronchioles]] of cats
*''Filaroides osleri'' causes infection in [[Respiratory Parasitic Infections - Pathology#Filaroides osleri|trachea]]
*''Filaroides osleri'' causes infection in [[Respiratory Parasitic Infections - Pathology#Filaroides osleri|trachea]] of dogs
*''Metastrongylus'' spp. in [[Respiratory Parasitic Infections - Pathology#Metastrongylus spp.|bronchi]] of pigs
*''Metastrongylus'' spp. in [[Respiratory Parasitic Infections - Pathology#Metastrongylus spp.|bronchi]] of pigs