Giardia | Parasites | CDC - Centers for Disease Control and Prevention
https://www.cdc.gov/parasites/giardia/
Jul 22, 2015 - Giardia is a microscopic parasite that causes the diarrheal illness known as giardiasis. Giardia (also known as Giardia intestinalis, Giardia ...
Centers for Disease Control and Prevention
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Giardia - Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Giardia
Giardia
is a genus of anaerobic flagellated protozoan parasites of the phylum
Sarcomastigophora that colonise and reproduce in the small intestines of
several
Wikipedia
Giardia infection (giardiasis) - Mayo Clinic
www.mayoclinic.org/diseases-conditions/giardia.../con-20024686
Giardia infection is an intestinal infection marked by abdominal cramps, bloating, nausea and bouts of watery diarrhea. Giardia infection is caused by a ...
Mayo Clinic
| Giardia | |
|---|---|
 |
|
| Giardia trophozoite, SEM | |
| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | Excavata |
| Phylum: | Sarcomastigophora |
| Class: | Zoomastigophora |
| Order: | Diplomonadida |
| Family: | Hexamitidae |
| Genus: | Giardia Künstler, 1882 |
| species | |
|
Giardia agilis Giardia ardeae Giardia lamblia Giardia microti Giardia muris Giardia psittaci |
|
Contents
Characteristics
Like other diplomonads, Giardia have two nuclei, each with four associated flagella, and were thought to lack both mitochondria and a Golgi apparatus. However they are now known to possess a complex endomembrane system as well as mitochondrial remnants, called mitosomes, through mitochondrial reduction. [3] [4][5] The mitosomes are not used in ATP synthesis the way mitochondria are, but are involved in the maturation of iron-sulfur proteins.[6] The synapomorphies of genus Giardia include cells with duplicate organelles, absence of cytostomes, and ventral adhesive disc.[7]Infection and symptoms
A SEM micrograph of the small intestine of a gerbil infested with Giardia reveals a mucosa surface almost entirely obscured by attached trophozoites
Main article: Giardiasis
Giardia lives in the intestines of infected humans or other animals, individuals of which become infected by ingesting or coming into contact with contaminated food, soil, or water tainted by the feces of an infected carrier.[8]The symptoms of Giardia, which may begin to appear 2 days after infection, include violent diarrhea, excess gas, stomach or abdominal cramps, upset stomach, and nausea. Resulting dehydration and nutritional loss may need immediate treatment. A typical infection can be slight, resolve without treatment, and last between 2–6 weeks, although it can sometimes last longer and/or be more severe. Coexistence with the parasite is possible (symptoms fade), but an infected individual can remain a carrier and transmit it to others. Medication containing tinidazole or metronidazole decreases symptoms and time to resolution. Albendazole is also used, and has an anti-helmintic (anti-worm) property as well, ideal for certain compounded issues when a general vermicidal agent is preferred. Giardia causes a disease called Giardiasis, which causes the villi of the small intestine to atrophy and flatten, resulting in malabsorption in the intestine. Lactose intolerance can persist after the eradication of Giardia from the digestive tract.[9]
Prevention
Main article: Giardiasis
Person-to-person transmission accounts for the majority of Giardia infections and is usually associated with poor hygiene and sanitation. Giardia
is found on the surface of the ground, in the soil, in undercooked
foods, and water along with improper cleaning of fecal material from the
hands after handling infected feces.[10]
Water-borne transmission is associated with the ingestion of
contaminated water. In the U.S., outbreaks typically occur in small
water systems using inadequately treated surface water. Venereal
transmission happens through fecal-oral contamination. Additionally,
diaper changing and inadequate hand washing are risk factors for
transmission from infected children. Lastly, food-borne epidemics of Giardia have developed through the contamination of food by infected food-handlers.[11]The CDC recommends hand-washing and avoiding potentially contaminated food and untreated water.[12]
Boiling suspect water for one minute is the surest method to make water safe to drink and kill disease-causing microorganisms such as Giardia lamblia if in doubt about whether water is infected.[13] Chemical disinfectants or filters may be used.[14][15]
According to a review of the literature from 2000, there is little evidence linking the drinking of water in the N. American wilderness and Giardia.[16] The researcher notes that treatment of drinking water for Giardia may not be as important as recommended hand-washing in wilderness regions in North America.[16] CDC surveillance data (for 2005 and 2006) reports one outbreak (6 cases) of waterborne giardiasis contracted from drinking wilderness river water in Colorado.[17] However, less than 1% of reported giardiasis cases are associated with outbreaks.[18]
Systematics
About 40 species have been described from different animals, but many of them are probably synonyms.[19] Currently, five to six morphologically distinct species are recognised.[20] Giardia lamblia (=G. intestinalis, =G. duodenalis) infect humans and other mammals, G. muris is found from other mammals, G. ardeae and G. psittaci from birds, G. agilis from amphibians and G. microti from voles.[2] Other described, (but not certainly valid) species include:[21] Many different species of Giardia exist and to discriminate between species very specific PCR (Polymerase Chain Reactions) have been developed to detect specific Giardia spp. Gene probe-based detection is also used to differentiate between species of Giardia. A more common and less time consuming means of identifying different species of Giardia includes microscopy and immunofluorescence techniques.[22]- Giardia beckeri
- Giardia beltrani
- Giardia botauri
- Giardia bovis
- Giardia bradypi
- Giardia canis
- Giardia caprae
- Giardia cati
- Giardia caviae
- Giardia chinchillae
- Giardia dasi
- Giardia equii
- Giardia floridae
- Giardia hegneri
- Giardia herodiadis
- Giardia hyderabadensis
- Giardia irarae
- Giardia marginalis
- Giardia melospizae
- Giardia nycticori
- Giardia ondatrae
- Giardia otomyis
- Giardia pitymysi
- Giardia pseudoardeae
- Giardia recurvirostrae
- Giardia sanguinis
- Giardia serpentis
- Giardia simoni
- Giardia sturnellae
- Giardia suricatae
- Giardia tucani
- Giardia varani
- Giardia viscaciae
- Giardia wenyoni
Genome
A Giardia isolate (WB) was the first diplomonad to have its genome sequenced. Its 11.7 million basepair genome is compact in structure and content with simplified basic cellular machineries and metabolism. Currently the genomes of several other Giardia isolates and diplomonads (the fish pathogens Spironucleus vortens and S. salmonicida) are being sequenced.[24]A second isolate (the B assemblage) from humans has been sequenced along with a species from a pig (the E assemblage).[25] There are ~5000 genes in the genome. The E assemblage is more closely related to the A assemblage than is the B. A number of chromosomal rearrangements are present.
See also
References
. PMID 11432808.. PMID 16040811.no
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