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Also known as the ''''lungworms'''', but beware! - not all worms in the lungs are metastrongyloids!
== General Appearance ==
*Bursate.
*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.
== General Life-Cycle ==
*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).
*Adult female lungworms → eggs → wafted up trachea by epithelial cilia → throat → swallowed → pass through alimentary tract.
*Eggs typically hatch en route → L1 in faeces.
*L1 has a wavy tail and some soecies also have a sub-terminal peg.
*L1 eaten by mollusc intermediate host → infetive 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.
*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.
*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, byt 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]]