Morphology of Giardia
It exists in 2 morphological forms-
- Feeding/ Trophozoite stage
- Infective Cyst stage
Feeding/ Trophozoite Stage
Giardia intestinalis causes sickness through its trophozoites stage. This cell is around 12 to 15 μm length and 5 to 9 μm broad, giving it the appearance of a microscopic half-pear. The two nuclei of the trophozoite are symmetrically positioned in the anterior area.
- The parasite’s colonization of the intestine occurs during its active feeding stage.
- Trophozoites are shaped like pears or tennis rackets.
- The ventral surface has an adhesive disc and is concave, whereas the dorsal surface is convex.
- Every bodily organ is paired, and it is bilaterally symmetrical. They have two axostyles, two median bodies, two nuclei, and four pairs of flagella.
- Each nucleus is made up of a sizable central karyosome, which gives the parasite in stained preparation a distinctive face-like appearance.
- The motility displayed the usual falling leaf-type motility.
- On the ventral surface of the broad or anterior end, there is a bean-shaped sucking disc.
Cyst (Infective Stage)
Humans can contract the infectious stage of the cyst stage by consuming as low as 10–25 cysts. Once excystation occurs, these cysts mature into trophozoites.
- It is an infective stage of a parasite.
- A fully mature cyst is oval or ellipsoidal in shape and measures 8-13 micrometre in length and 7 – 10 micrometre in breadth.
- The cyst is surrounded by a thick cyst wall. There is a clear space separating the granular cytoplasm from the cyst wall.
- The axostyle lies more or less diagonally.
- A cyst contains 4 nuclei.
- A remaining flagella and the margins of the sucking disc may be seen inside the cytoplasm.
- Each cyst gives rise to two trophozoites during excystation in the intestinal tract.
Giardia Life Cycle
The Giardia life cycle starts in contaminated water or food, where cysts are ingested and then transform into trophozoites in the host’s intestines. Understanding Giardia life cycle stages and transmission helps in implementing effective prevention strategies and minimizing the spread of this parasitic infection.
In this article, we will cover in detail the life cycle of Giardia and its diagram.
Table of Content
- Life Cycle of Giardia
- Giardia Life Cycle Stages
- 1. Cyst
- 2. Excystation
- 3. Trophozoites
- 4. Encystation
- Scientific Classification of Giardia
- Morphology
- Feeding/ Trophozoite stage
- Cyst (Infective Stage)
- Pathogenesis
- Mode of transmission:
- Symptoms
- Diagonsis
- Treatment and Prevention
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