the inhibitory properties of and mode of action of plant essential oils ...

antibodies generated against proteins of the endomembrane system showed that cyst
wall proteins were exported through the re-organisation membrane compartments
that were biochemically similar to ESVs (Marti et al. 2003). These results
demonstrate ESVs are part of a Golgi cisternae-like system which is constitutively
expressed rather than being generated de novo.
Excystation
Within the mammalian host, excystation occurs rapidly after passage through the
acidic environment of the stomach and after entry into and exposure to elements of
the proximal small intestine (Adam 2001). Excystation was first induced in vitro
using acidic solutions (optimum pH 1.3 – 2.7; Bingham & Meyer 1979) which
suggest an importance of passage through the acidic environment of the stomach for
excystation. This may not always be the case, with G. muris excystation having
occurred in vitro at pH 7.5 in vitro (Feely, Gardner and Hardin 1991) and may
explain cases of giardiasis in patients with reduced gastric acidity. Subsequently a pH
of 4 has been assessed as the optimum pH and that the use of pancreatic proteases
such as trypsin or chymotrypsin being required for in vitro excystation and suggest
the role for pancreatic secretions for excystation in vivo (Boucher & Gillin 1990).
Life cycle
Humans are indicated as reservoirs of this protozoan, although other mammals
including dogs, cats, farm animals and beavers have been shown to harbour Giardia
(Ortega & Adam 1997; McGlade et al. 2003; Hunter & Thompson 2005).
Transmission in humans may occur via direct faecal-oral contact or from faecally
contaminated water and food (Smith et al. 2007). The zoonotic transmission of
Giardia is still unclear but has been described in northeast India from dogs (Traub et
al. 2004) and direct contact with farm animals and pets have also been associated
with giardia infection (Warburton, Jones and Bruce 1994; Hunter & Thompson
2005).
The infection cycle begins with the consumption of infective cysts, usually from the
faecal-oral route by contaminated food or water (Figure 1.5). After the safe passage
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