''Metastrongylus'' is a genus of

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s of the family

Metastrongylidae The Metastrongylidae are a family of nematodes. Genera in the family Metastrongylidae include: * ''Aelurostrongylus ''Aelurostrongylus'' is a genus of nematodes The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nema ...

, usually found as

lungworm Lungworms are parasitic nematode worms of the order Strongylida that infest the lungs of vertebrates. The name is used for a variety of different groups of nematodes, some of which also have other common names; what they have in common is that t ...

s in

pig The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...

s and sometimes causing

parasitic bronchitis Parasitic bronchitis, also known as hoose, husk, or verminous bronchitis, is a disease of sheep, cattle, goats, and swine caused by the presence of various species of parasite, commonly known as lungworms, in the bronchial tubes or in the lungs. ...

. It causes a disease called metastrongylosis.

Species

*'' Metastrongylus elongatus'' (Dujardin, 1845) synonym '' Metastrongylus apri'' (Gmelin, 1780) *'' Metastrongylus pudendotectus'' (Wostokow, 1905) *'' Metastrongylus salmi'' (Gedoelst, 1823) *'' Metastrongylus confusus'' (Jansen, 1964) *'' Metastrongylus asymmetricus'' (Noda, 1973)

Life cycle

The lifecycle is indirect. The

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

are laid by the adult

worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. Worms vary in size from microscopic to over in length for marine ...

in the

bronchi A bronchus ( ; : bronchi, ) is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus. Thes ...

. They are coughed up, swallowed, and passed out via the

feces Feces (also known as faeces American and British English spelling differences#ae and oe, or fæces; : faex) are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the ...

. The eggs are then eaten by

earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...

s in which they develop through three

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l stages over 10 days to become infective. The cycle is completed by the

eating the earthworm. Infection, therefore, only occurs where pigs have access to earthworms, for example, in outdoor production. The larvae from the earthworm penetrate the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

and migrate via the

lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...

s and

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

s to the

lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

s, undergoing two more larval stages in the process. The prepatent period is 3-4 weeks.

References

Strongylida Swine diseases Veterinary helminthology Parasitic nematodes of mammals Rhabditida genera {{Rhabditida-stub