Giardia lamblia
Giardia intestinalis
Giardia intestinalis (syn. G. lamblia, G. duodenalis ) is a protozoan parasite of the genus Giardia, human (→ giardiasis ), other mammals (→ giardiasis of the dog, the cat giardiasis ) amphibians, reptiles and birds infests. It is named after Alfred Mathieu Giard and Vilém Dušan Lambl. He usually passes through contaminated surface water, in which its survival structures ( cysts ) are, or - less frequently - about contacts with flying in the human gut. Cats and chinchillas Giardia intestinalis is one of the parasites which are found most commonly in Kotuntersuchungen.
Giardia intestinalis is a primitive single-celled organisms whose evolution among biologists still raises many unanswered questions.
Features
Trophozoites are the active forms of the protozoan in the intestine and only they procreate. They are oval, elongated and about 9-20 microns long and 5-12 microns wide. Each individual has two nuclei, and four pairs of flagellum, two of which are in the middle of the cell and a further two lateral spring. In addition, the trophozoites on the ventral possess a holdfast with which they cling to the intestinal epithelium.
Cysts are a protective sheath provided permanent molds and very resistant to environmental influences. They are about 8-15 microns × 7-10 microns in size. Cysts are excreted by infected creatures and can survive for up to four months in surface water (such as lakes ). In the gut, these convert back into trophozoites.
Special features of Giardia intestinalis are:
- Giardia intestinalis has no mitochondria and no peroxisomes, but iron -sulfur cluster -synthesizing Mitosomen and genetic material which contains mitochondrial genes. It is believed that Giardia has lost its mitochondria again in the course of evolution.
- The genome is highly variable. It contains from 12 to about 80 million base pairs, which are distributed over 8 to 50 chromosomes.
- Sexual maturation division (meiosis ) has never been observed, but genes have been found for this process.
- In the jejunum are only trophozoites, but in the ileum only cysts. Lack of cholesterol is responsible for ensuring that the Trophozoitenoberfläche can no longer be formed. This leads to cyst formation ( encystment ).
Using molecular biology techniques, different genotypes are now distinguished. While the genotypes A ( divided partly into the subgroups AI, AII ) and B apparently have a zoonotic potential and can infect both humans as well as dogs and cats, the remaining genotypes are apparently host specific. Genotype C and D comes in dogs ( and cats D ), genotype E in ungulates, genotype F in cats and genotype G in rodents before. In chinchillas, especially type B is observed.
Epidemiology
About 10 % of the world population is infected with Giardia. Above all, children are the victims here. Under tropical travelers it is the most common protozoan infection.
Disease
The Giardia infection usually remains unnoticed. Sometimes patients complain of bloating, pressure pain around the navel and / or diarrhea. Even weight losses are not uncommon. For the therapy of metronidazole is often used.
Terms of Use
In Germany there is a reporting obligation in Giardia intestinalis infection in § 7 Infection Protection Act (IfSG ), but not in Austria and Switzerland.