Giant scratches
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Giant Scraper ( Macracanthorhynchus hirudinaceus ) |
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| Macracanthorhynchus hirudinaceus | ||||||||||||
| Pallas , 1781 |
The giant scraper ( Macracanthorhynchus hirudinaceus ) is a type of scratchworm (Acanthocephala) that lives as an intestinal parasite mainly in wild and domestic pigs and triggers macracanthorhynchosis in the pig . It is also a potential intestinal parasite in humans, which it attacks and can trigger intestinal perforations, but does not become sexually mature in it and accordingly does not produce any eggs.
features
Female giant scratchers reach a body length of up to 70 centimeters, while the males remain significantly smaller with a maximum of around nine centimeters. The animals have a smooth body that is curved ventrally. The proboscis (proboscis) is relatively small in relation to the body and is oval to spherical in shape and has six spiral rows of hooks of five to six hooks each, the hooks on the base of the trunk being particularly small. Corresponding to the small proboscis, the proboscis sheath and the band-shaped lemnisci are only relatively short.
The females, like all Archiacanthocephala, have a dorsal and a ventral ligament sac in the pseudocoel , the walls of which, unlike those of the Palaeacanthocephala, do not dissolve, and the giant scratchers have protonephridia . The eight cement glands of the males are arranged in pairs and are very close to each other, the testicles are far forward in the body of the animals.
The eggs are oval with a thick, multi-layered egg shell and have a surface with a clear net-like structure made up of several ridges and dents. They are 85 to 95 micrometers long and 51 to 56 micrometers wide.
Way of life
The giant scratcher lives as an adult animal as an intestinal parasite in the intestines of pigs, but can also infect humans and dogs in very rare cases. The females lay around 80,000 eggs daily, which means that the reproduction rate is very high. These eggs already contain the first larval stage of the scratch worms, the acanthor .
The eggs get on and into the ground with the pigs' faeces, where they are ingested by various beetle larvae. Larvae of scarab beetles (Scarabaeidae) and ground beetles (Carabidae), especially May , June or rose beetles, serve as intermediate hosts . In the intermediate host, development takes place up to the Acanthella and Cystacanthus stage, in which the larvae are consumed by the grazing and burrowing pigs with the grubs as food. The prepatency , i.e. the time from ingestion to the settlement of the parasite and the first detection, takes about 10 to 11 weeks for this species.
In the intestine, the scratch digs deep into the muscular tissue of the small intestine , the tunica muscularis , with the help of the hooked proboscis , and gets caught there. This mechanical process leads to heavy bleeding ( haemorrhages ), an increase in the number of eosinophilic granulocytes in the blood to defend against parasites ( eosinophilia ) and an increase in the growth of connective tissue (connective tissue proliferation) in the area of the affected intestinal area, which is then externally recognizable due to the button-like thickening is. In the case of more severe infections, especially in younger pigs, developmental disorders due to malnutrition, anemia , diarrhea , reluctance to eat and pain reactions can appear.
Relevance as a parasite
Main article: Macracanthorhynchose of the pig
The Macracanthorhynchose of the domestic pig is mainly found in countries and regions in which pigs are kept in open pasture. In most regions of Central Europe, in which pig farming is now practiced as intensive stables, it does not occur. Internationally, macracanthorhynchosis is a very common parasitosis.
literature
- Theodor Hiepe, Renate Buchwalder, Siegfried Nickel: Textbook of Parasitology. Volume 3: Veterinary Helminthology. Gustav Fischer Verlag, Jena 1985; Pages 393-394
- Michel Rommel, Johannes Eckert, Erich Kutzer, Wolfgang Körting, Thomas Schnieder: Veterinary Parasitology. 5th edition, Parey Buchverlag, Berlin 2000; Page 483.
