in vitro culture and isoenzyme analysis of giardia lamblia

Observations
• A large proportion of cysts separated using ZnS04 floatation appeared granular
intracellularly, even though attempts were made to remove the ZnS04 solution
by washing as soon as possible.
• Fluid and semi-formed stool specimens were much easier to separate and
produced cleaner cysts than hard-formed stools, which required repeated
gradient separations.
• Upon examination of the deposits obtained after retrieving cysts from the
respective gradient material, more cyst losses were observed on the two
sucrose gradient techniques compared to that obtained from the ZnS04
sediment after cysts were retrieved from the float.
2.3.3 Total Cyst Counts
After purification, all cyst suspensions were enumerated on a Neubauer counting
chamber and all results appear in Appendices 3-5. Fifty-two samples contained
very scanty Giardia cysts (detected on the formol-ether concentrated samples). In
addition, many of these were non-viable and were therefore considered unsuitable
for experimental work.
2.3.4 Cyst Viability
Direct observation of cysts under a light microscope allowed for a qualitative
differentiation of viable and non-viable cysts. The former were recognised by their
highly refractile cyst wall and clearly defined internal features which are closely
adherent to the cyst wall. Similarly, in eosin stained preparations, viable cysts
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