in vitro culture and isoenzyme analysis of giardia lamblia

of (a) the enormous absorptive capacity of the small bowel (Hill, 1990) and, (b)
fewer parasites were isolated in some patients with marked symptoms (Wolfe,
1979). However, Buret (1994) recently stated that the parasite burden contributes
to the pathology of giardiasis.
Production of diarrhoea has been ascribed to bacterial overgrowth and bile salt
deconjugation, which is common in giardiasis (Tandon et al., 1977). On the
contrary, Nash and colleagues (1987) found that bacterial overgrowth was not
associated with symptomatic giardiasis in studies of infected human volunteers.
Saha and Ghosh (1977) reported superficial invasion of intestinal mucosa in
human infection which was associated with steatorrhoea; however, contradictory
findings were reported by Owen and co-workers (1979) in their observations of
murine giardiasis. They reported that "in animals with intact epithelium, Giardia are
rare beneath the surface and that penetration probably occurs when trophozoites,
randomly moving forward, enter disruptions in the epithelium or cavities left by
desquamating cells." A recent finding by Nash and Mowatt (1993) indicated that
the variant-specific cysteine-rich surface proteins have a high affinity for certain
metals, including zinc. These proteins then can act as a "zinc sink" in which the
cations are trapped (on the surface of the trophozoites) and thus rendered
unavailable for digestion and absorption functions. They proposed that
malabsorption could be caused by zinc deficiency resulting in inhibition of all zincdependant
enzymes.
Roberts-Thompson (1993) affirmed that the reasons for the development of
diarrhoea resulting from infection with Giardia species remain unclear. However,
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