In contrast to encystion, excystation is a very fast
process that is completed within 2 h, suggesting that
signaling is very important. Although the in vitro
excystation method has been described two decades
ago, it remains a challenging technique that is highly
sensitive to inter-laboratory variation, explaining why
only few quantitative excystation studies have been
published. The efficiency of excystation of human
Giardia cysts formed in vitro depends on the biological quality or maturity of the cysts. Excystation of