Related Experiment Video
Updated: Aug 2, 2026
Mass Isolation and In Vitro Cultivation of Intramolluscan Stages of the Human Blood Fluke Schistosoma Mansoni
Published on: January 14, 2018
In vitro excystation and subsequent axenic growth of Giardia lamblia
M A Hautus1, L M Kortbeek, J C Vetter
1Laboratory of Parasitology, University of Amsterdam, The Netherlands.
Abstract:
Six fresh Giardia lamblia strains were isolated by in vitro excystation and subsequent culturing of excysted parasites in bile-supplemented BI-S-33 medium. The cysts passed in faeces appeared to differ in structure when observed using differential interference contrast microscopy. Sometimes the enclosed organisms were closely applied to the cyst wall; in most stool specimens, however, the parasites were separated from the cyst wall by a space. Cysts with parasites closely applied to the wall were the most viable type, with excystation rates up to 90%. Cysts with organisms detached from the wall displayed low excystation rates, 0-15%. During exposure to the induction solution of hydrochloric acid (pH 2), parasites initially closely applied to the cyst walls completely detached, and after transfer into culture medium vigorous flexing movements of the organisms were observed. Stool samples from 42 symptomatic and asymptomatic giardiasis patients were examined; in 26 of the samples parasites hatched, and 6 new strains were established in axenic culture.
Insights
Giardia lamblia cyst structure impacts excystation viability. Cysts with internal parasites attached to the wall show higher excystation rates, crucial for understanding giardiasis transmission.
Area of Science:
- Microbiology
- Parasitology
- Cell Biology
Background:
- Giardia lamblia is a significant cause of waterborne illness globally.
- Understanding cyst viability is key to controlling giardiasis outbreaks.
- Parasite-cyst wall interaction in Giardia lamblia remains incompletely understood.
Purpose of the Study:
- To investigate the relationship between Giardia lamblia cyst structure and excystation viability.
- To characterize morphological differences in Giardia lamblia cysts found in patient stool samples.
- To establish new Giardia lamblia strains for further research.
Main Methods:
- Isolation of Giardia lamblia strains through in vitro excystation and axenic culture.
- Microscopic examination of cysts using differential interference contrast microscopy.
- Assessment of excystation rates under varying conditions, including acid exposure.
Main Results:
- Two distinct Giardia lamblia cyst morphologies were observed: parasites closely applied to the cyst wall and parasites detached from the wall.
- Cysts with internal parasites attached to the wall exhibited high excystation rates (up to 90%).
- Cysts with detached parasites showed significantly lower excystation rates (0-15%), with detachment induced by acid exposure.
Conclusions:
- The structural integrity and proximity of Giardia lamblia internal parasites to the cyst wall are critical indicators of viability.
- Morphological changes in cysts, particularly parasite detachment, correlate with reduced excystation potential.
- These findings offer insights into Giardia lamblia excystation mechanisms and potential diagnostic markers for infectivity.
