Final answer:
Giardia lamblia is a protozoan parasite that exists in two forms: the cyst and the trophozoite. It causes giardiasis, which is transmitted through contaminated food or water and identified by microscopy, showing a symmetrical shape with flagella and unique fluorescent characteristics.
Step-by-step explanation:
Giardia lamblia (Cyst & Trophozoite)
The organism Giardia lamblia is a single-celled, flagellated protozoan that parasitizes the gastrointestinal tract of humans and various animal species. In its lifecycle, it exists in two forms: the cyst and the trophozoite. The cyst is the dormant, hardy stage that can survive outside the host in various environments and is responsible for transmission of the infection. Meanwhile, the trophozoite is the active, vegetative form that multiplies within the host's intestines, causing symptoms of giardiasis, such as severe diarrhea and nutritional malabsorption.
Under scanning electron microscopy, Giardia lamblia is distinguished by its unique appearance, featuring a symmetrical shape with two nuclei and several flagella, aiding in attachment to the intestinal lining and movement. Although this protozoan lacks functional mitochondria, it contains mitosomes, remnants of mitochondria that contribute to iron and sulfur metabolism. It proliferates in an anaerobic environment and relies on alternative energy-generating pathways like glycolysis due to its biochemically reduced organelles.
Transmission of Giardia usually occurs through the fecal-oral route, chiefly by ingesting contaminated food or water, and can cause a type of gastroenteritis known as giardiasis. Effective diagnosis often involves identifying Giardia cysts or trophozoites in stool samples and can be highlighted by a blue halo under ultraviolet fluorescence microscopy.