in vitro culture and isoenzyme analysis of giardia lamblia

To-date, use of the different specific names for human isolates (viz. G.Jamblia,
G.duodena/is and G.intestinalis) appears to be based on personal preference.
Although Mayrhofer et al. (1995) stated that those Giardia that infect humans
belong to the morphologic group G.duodenalis but have been assigned to a
separate species G.intestinalis (or G./amb/ia) on the basis of presumed hostspecificity,
attempts to obtain literature that documents some consensus regarding
the specific name for the human isolates were futile.
Lymbery and Tibayrenc (1994) quite correctly stated that the species level
systematics have not been resolved. Furthermore, there is increasing evidence
that the Giardia infecting humans comprise a species complex. For example,
Andrews et al. (1989) used isoenzyme electrophoresis to characterise 29
Australasian human isolates and 48 clones from these strains. Four distinct types
were identified based on the 26 enzyme patterns. Recently, Upcrofft et a/.,(1995)
characterised 40 stocks of Giardia using biochemical characteristics (karyotype,
RFLP and rDNA analyses) over eleven years (1982-1993). During this period at
least two major varieties had infected the population of Southeast Queensland.
This additional diversity among the human isolates may further complicate the
present classification problems currently faCing taxonomists. However, it is
anticipated that with the advent of advanced molecular typing techniques, the state
of flux existing in Giardia taxonomy will be resolved.
In the light of a lack of consensus on Giardia nomenclature at present, the name
Giardia lamb/ia will be used in the current study to describe all isolates obtained
from humans.
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