''Setaria cervi'' is a species of parasitic

roundworms The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

belonging to the genus ''

Setaria ''Setaria'' is a widespread genus of plants in the grass family. The name is derived from the Latin word ''seta'', meaning "bristle" or "hair", which refers to the bristly spikelets. The genus includes over 100 species distributed in many tr ...

''. It infects cattle, bison, yak, reindeer, buffalo, moose, and sheep all over the world. It is most prevalent in Europe and Asia. Different species of ''

Aedes ''Aedes'' is a genus of mosquitoes originally found in tropical and subtropical zones, but now found on all continents except perhaps Antarctica. Some species have been spread by human activity: ''Aedes albopictus'', a particularly invasive spe ...

'' mosquito can transmit the filarial worm. Stable fly ''Haematobia stimulans'' is the major vector. The mature roundworms are primarily present in the abdominal (peritoneal) cavity, but are capable of migrating to

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

causing serious

neurological disease A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakness ...

Description

''Setaria cervi'' shows

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

as a typical roundworm. Males are relatively smaller measuring 50 mm long and 40 μm wide, while females are much larger measuring 100 mm long and 750 μm wide. Males can be distinguished from those of other species from showing horn-like lateral appendages and characteristic striated bands on the ventral side of the tail. The larvae (microfilariae) are very small and only about 200 μm long. The infective larvae are about 2 mm.

Life cycle

''Setaria cervi'' is transmitted between mammals as

definitive host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

s and insects as

intermediate hosts In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

. Microfilariae are ingested by insect vector when they bite infected host. Once inside the gut of the insect, the larvae shed off their protective covering, a process called exsheathing. This generally take place within 90 minutes of initial ingestion. They penetrate the stomach wall and migrate to the body cavity,

haemocoel The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

. After 48 hours they move to fat bodies, where they undergo development by

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

. Second moulting follows after 11 days of infection. Soon after, the juveniles move back to haemocoel to become fully infective larvae. Then they move towards the proboscis from where they are readily released. Infective larvae are characterised by numerous projections called tubercles on the tail end. The infective larvae are injected into the mammalian host, where they undergo third moulting. By this the size of the body is greatly enlarged. Full maturation into reproductive adults require about a year. The average lifespan of an adult is 1.5 years.

Pathogenicity

''Setaria cervi'' in the body cavity is generally harmless. But the young larvae upon infection can move to the nervous system, where they induce severe neurological disease, as well as in the eye, where they can cause eye damage resulting in blindness.

Treatment

Albendazole Albendazole (also known as albendazolum) is a broad-spectrum anthelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, h ...

is very effective on the microfilariae. Hetrazan,

tetramisole Levamisole, sold under the brand name Ergamisol among others, is a medication used to treat parasitic worm infections, specifically ascariasis and hookworm infections. It is taken by mouth. Side effects may include abdominal pain, vomiting, he ...

and

levamisole Levamisole, sold under the brand name Ergamisol among others, is a medication used to treat parasitic worm infections, specifically ascariasis and hookworm infections. It is taken by mouth. Side effects may include abdominal pain, vomiting, he ...

are most commonly used.

References

External links

Classification at Encyclopedia of Life
{{Taxonbar, from=Q10666506 Spirurida Parasitic nematodes of mammals Nematodes described in 1819 Taxa named by Karl Rudolphi