Esophageal worm
| Esophageal worm | ||||||||||||
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Embryonated egg of the esophagus worm |
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| Scientific name | ||||||||||||
| Spirocerca lupi | ||||||||||||
| ( Rudolphi , 1809) |
The esophagus worm ( Spirocerca lupi ) is a roundworm that can attack the esophagus of dogs as an endoparasite .
description
Esophagus worms are bright red round worms of a cylindrical shape. Male adult worms are approximately 40 mm long and female worms are approximately 70 mm. The mouth opening has six lips. The oral capsule is well developed and has thick walls. The cuticle , formed by excretions from the epidermis , has three layers and consists of collagen and other substances; it serves to protect the worms from digestion .
distribution
The esophagus worm is particularly widespread in the southern United States , but occurs worldwide in tropical and subtropical regions. Dogs are primarily affected as the ultimate host , but the infestation has also been described in the case of black horned hyenas . The parasite is of particular veterinary relevance in domestic dogs .
Life cycle
Adult worms nest in the wall of the esophagus (and sometimes the wall of the stomach ), where they mate and release eggs into the esophagus, which are excreted in the feces. The eggs are longitudinally oval, measure approximately 11–15 × 30–38 μm and already contain one larva. Eggs are laid in batches so that infected animals are only intermittent shedders, which can make parasitological diagnosis difficult.
The eggs in the feces are ingested by coprophage insects (mostly dung beetles ) as intermediate hosts . The larvae molt to larva 3 (L3) while still in the egg, then hatch and form cysts in the intermediate host . The intermediate hosts can infect the ultimate host directly, but the parasites also often accumulate in forage hosts such as lizards , chickens or mice .
If the definitive host takes on an intermediate or collective host, the infectious L3 penetrate into the stomach wall and migrate from there through the wall of the celiac trunk into the aortic wall , where they arrive about 20 days after infection. After two to three months, they migrate out of the aortic wall into the esophageal wall, where they molt into adult worms, mate and again secrete eggs through which new intermediate hosts can become infected. The prepatency is five to six months.
In response to the parasites, granulomas develop in the esophageal wall , which can degenerate into malignant tumors ; mostly sarcomas ( fibrosarcomas and osteosarcomas ), occasionally squamous cell carcinomas . While migrating into the aortic wall, the parasites can also lead to the formation of aneurysms .
literature
- LL van der Merwe, RM Kirberger, S. Clift, M. Williams, N. Keller, V. Naidoo: Spirocerca lupi infection in the dog: a review. In: Veterinary journal (London, England: 1997). Volume 176, Number 3, June 2008, pp. 294-309, ISSN 1090-0233 . doi : 10.1016 / j.tvjl.2007.02.032 . PMID 17512766 . (Review).
- RC Chhabra, KS Singh: On the life cycle of Spirocerca lupi: preinfective stages in the intermediate host. In: Journal of helminthology. Volume 46, Number 2, 1972, pp. 125-137, ISSN 0022-149X . PMID 5086229 .
Web links
- Aortic damage from S. lupi on the Cornell University site
- Histology image on Cornell University page
Individual evidence
- ↑ a b c d Spirocerca lupi in the Encyclopedia of Life
- ^ MGL Mills: Hyaena brunnea. In: Mammalian Species 194 (1982), p. 3. PDF
- ^ A b c Spirocerca lupi in Small Animals , The Merck Veterinary Manual