Overview

Distribution

The geographic range of Lagochilascaris minor is yet to be specifically identified. It is most frequently found in neotropical areas, with the greatest frequency in South America.

Biogeographic Regions: neotropical (Native )

  • Lanfredi, R., H. Neto, D. Gomes. 1998. Scanning Electron Microscopy of Lagochilascaris minor Leiper, 1909 (Nematoda: Ascarididae). Memorias do Instituto Oswaldo Cruz, 93(3): 327-330.
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Physical Description

Morphology

As a nematode, Lagochilascaris minor is cylindrical, has a cuticle with three main outer layers made of collagen and other compounds. The outer layers are non-cellular and are secreted by the epidermis. The cuticle layer protects the nematodes so they can invade the digestive tracts of animals.

Nematodes have longitudinal muscles along the body wall. The muscles are obliquely arranged in bands. Dorsal, ventral and longitudinal nerve cords are connected to the main body of the muscle.

Lagochilascaris minor is stout with tapered extremities. Males are smaller (6 mm) than the females (15 mm). The anterior end of both is domed shaped. This is formed by three wide lips that are separated from the rest of the body by a deep groove. The three lips center around the oral opening. There is a dorsal lip that has two sub-dorsal papilla, and a sub-ventral lip that has one ventral papillae. Near the anterior end resides the excretory pore, interrupting the cuticular striations.

Females have a long straight tail with the anus at the posterior end. The vulvar opening is located near the middle of the body. The posterior end of the males is ventrally curved. There are 22-28 pairs of preocloacal papillae which are sessile, button-like, and arranged in two lateroventral rows.

As a nematode in the group Secernentea, Lagochilascaris minor has a specialized tubular excretory system with three canals. The canals are arranged to form an “H”.

Range length: 6 to 15 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger; sexes shaped differently

  • Barnes, R. 1987. Invertebrate Zoology. Orlando, Florida: Dryden Press.
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Ecology

Habitat

There are no free living stages of Lagochilascaris minor, but true definitive hosts are unknown. Migration once inside the host varies. They have been found in the stomach, pharynx, trachea, tonsils, nose and neck of wild cats in South America and the Carribean. Occasionally they will infect humans and one fatality has been reported.

Habitat Regions: tropical

Terrestrial Biomes: forest ; rainforest ; scrub forest

  • Roberts, L., J. Janovy. 2000. Foundations of Parasitology, 6th Edition. USA: The McGraw-Hill Companies, Inc..
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Trophic Strategy

Adults are found in the upper digestive tract of the host, particularly in the crypts of the tonsils and the pharyngeal region. Lagochilascaris minor burrows into the mucosal lining and there resides, eventually forming abscesses in the host. Other biology concerning food habits is still unknown.

In general, nematode pharyngeal glands and intestinal epithelium produce digestive enzymes to feed on the hosts’ body fluids. Extracellular digestion begins within the lumen and is finished intracellularly.

Animal Foods: body fluids

Primary Diet: carnivore (Eats body fluids)

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Associations

There is little host specficity. Normally it is found in various cat species in South America, but can also parasitize humans, domestic and wild animals. However, the mode of host infection and the natural host remain yet unknown.

Ecosystem Impact: parasite

Species Used as Host:

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Predators are unknown. These parasites are probably not preyed on directly, but are ingested from host to host. Larval mortality is high as most of the parasites do not reach appropriate hosts.

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Life History and Behavior

Behavior

Nematodes within the Secernentea have phasmids, which are unicellular glands. Phasmids likely function as chemoreceptors. Females may produce pheromones to attract males.

Nematodes in general have papillae, setae and amphids as the main sense organs. Setae detect motion (mechanoreceptors), while amphids detect chemicals (chemoreceptors).

Communication Channels: tactile ; chemical

Other Communication Modes: pheromones

Perception Channels: tactile ; chemical

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Life Cycle

Research supports that L. minor is heteroxenous with the eggs usually hatching in water. Once exposed to air the eggs molt into a second stage larva within eight days. The larva has an aboring tooth for burrowing and a knobbed tail. The second stage larva then moults into a third stage larva. From this point on L. minor follows typical ascaridoid development.

  • Sprent, J. 1971. Speciation and Development in the Genus Lagochilascaris. Parasitology, 62: 71-112.
  • Volcan, G., C. Medran, G. Payares. 1992. Experimental Heterozenious Cycle of Lagochilascaris minor Leiper, 1909 (Nematoda: Ascarididae) in White Mice and Cats. Memorias do Instituto Oswaldo Cruz, 87: 525-532.
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Reproduction

This species is dioceious, but exact mating behavior is still unknown. Females may produce a phermomone to attract males. The male coils around a female with his curved area over the female genital pore. The gubernaculum, made of cuticle tissue, guides spicules which extend through the cloaca and anus. Males use spicules to hold the female during copulation. Nematode sperm are amoeboid-like and lack flagella.

Key Reproductive Features: sexual ; fertilization (Internal ); oviparous

Parental Investment: pre-fertilization (Provisioning)

  • Barnes, R. 1987. Invertebrate Zoology. Orlando, Florida: Dryden Press.
  • Roberts, L., J. Janovy. 2000. Foundations of Parasitology, 6th Edition. USA: The McGraw-Hill Companies, Inc..
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Relevance to Humans and Ecosystems

Benefits

In humans, Lagochilascaris minor will form abscesses that will contian its offspring. These abscesses can be found in the ear, neck, jaw, orbit, mastoid process, and retropharyngeal tissues. These infections can kill quickly or last years. There have only been eight documented cases.

Negative Impacts: injures humans (causes disease in humans ); causes or carries domestic animal disease

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