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A direct immunofluorescence assay (DFA) is available for diagnosing Giardia duodenalis infections. Antibodies tagged with fluorescent markers are added to stool and incubated. Visualization under a fluorescent microscope shows the Giardia cysts as green, glowing ovoid objects.
- Overview
- Classification of Giardia
- Host Specificity and Morphological Differences of Giardia Species
- Cell Biology
- Life Cycle
- Excystation
- Encystation
- Reproduction
- Giardiasis
- Microscopy
Giardia is a genus consisting of a number of flagellated species with similar morphological characteristics. Members of this genus can be found in various environments (water, soil etc) and are responsible for giardiasis (a diarrheal illness) in both human beings and other vertebrates. Given that the parasite is largely spread through the consumpti...
· Kingdom: Protista- Members are neither animals, fungi or plants. A majority of these organisms are single-celledwith unique and very diverse characteristics. · Subkingdom: Protozoa- falls under the kingdom Protista and consist of eukaryotic single-celled organisms that either exist as parasites or as free-living organisms. Giardia, which falls un...
While Giardia species have a number of similar morphological characteristics, they can be differentiated based on a number of structural differences and the hosts they infect. · Giardia agilis- Typically found in Amphibian hosts, G. agilis is characterized by a long and slender median body. · Giardia muris- Often affect rodents and are characterize...
Based on morphological studies, Giardia species have been shown to present simple structural organizations when compared to other eukaryotic cells. Following morphological studies on G. duodenalis, the organism was found to lack a number of organelles commonly found in other eukaryotic cells including mitochondria, peroxisomes as well as a well org...
The life cycle of Giardia consists of two main stages namely, the cyst stage and the trophozoite stage. Given that the cells go through the dormant cyst stage and the active/motile trophozoite stage, the whole life cycle can be said to go through two main processes that include the excystation and encystation stage.
Basically, excystation refers to the stage in the life cycle of the organisms where trophozoite(s) are released from the tough outer covering known as the cyst. The infective stage of the parasite (the cyst) has to be ingested by the appropriate host first. For the most part, this involves the consumption of contaminated foods or water. In the case...
As compared to excystation, encystation is the process through which the active and motile trophozoites are transformed into non-motile cysts (infective state). Whereas excystation is completed when the parasite reaches the less acidic conditions in the small intestine, encystation is stimulated by high bile levels as well as basic pH. This process...
In their life cycle, Giardia species have been shown to reproduce through asexual reproduction. Here, the trophozoites reproduce through simple binary fission(longitudinal binary fission). This is characterized by nuclei division followed by division of the cytoplasm. This restores the binucleated state with each daughter cell containing a copy of ...
As already mentioned, giardiasis is an infection of the small intestine caused by Giardia lamblia. While the parasite invades the small intestine (particularly duodenum), studies have shown that it does not penetrate cells of the small intestine. Moreover, it does not invade the epitheliumnor venture into the bloodstream. With regards to the mechan...
A number of techniques can be used to observe and study the morphological characteristics of Giardia species, these include:
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Sep 7, 2020 · Giardia lamblia is a pathogenic intestinal flagellate transmitted by the ingestion of contaminated water or food with the cyst stage of the parasite. Giardiasis can cause severe acute diarrhea and malabsorption or may persist as a chronic infection.
- Amjad Alharbi, Fawzia H Toulah, Majed H Wakid, Esam Azhar, Suha Farraj, Ahmed A Mirza
- 10.7759/cureus.10287
- 2020
- Cureus. 2020 Sep; 12(9): e10287.
Jun 29, 2018 · The laboratory diagnosis of Giardia spp. is mainly based on demonstration of microscopic cyst or trophozoite in stool samples but several immunological-based assays and molecular methods are also available for giardiasis diagnosis.
- Hossein Hooshyar, Parvin Rostamkhani, Mohsen Arbabi, Mahdi Delavari
- 2019
In bright-field microscopy, cysts appear ovoid to ellipsoid in shape and usually measure 11 to 14 μm (range: 8 to 19 μm). Immature and mature cysts have 2 and 4 nuclei, respectively. Intracytoplasmic fi brils are visible in cysts. Unstained cyst.
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Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations.
Jun 12, 2023 · Definition / general. Protozoan disease caused by Giardia lamblia / Giardia intestinalis, a common parasite that can be detected in small bowel biopsies; it can also be detected in stool. Clinical presentation ranges from asymptomatic shedding of giardial cysts to symptomatic giardiasis (i.e., malabsorption, chronic diarrhea) Essential features.
