in vitro culture and isoenzyme analysis of giardia lamblia

two factors are associated with the development of symptoms, namely the degree
of inflammatory changes in the small bowel and damage to microvilli, which lead to
a deficiency of brush border enzymes, particularly lactase.
1.5.2 Do host factors play a role in increasing the susceptibility of certain
hosts to infection?
Many variables such as age, sex, immune and nutritional status, ABO blood
groups, Human Leukocyte Antigen (HLA) type, socio-economic factors and gastric
acidity have been implicated in predisposing hosts to giardiasis. The exact nature
of the relationship between 'the disease and these factors has not been
conclusively described. Brief discussions on these factors are outlined in 1.7
below.
1.5.3 Are immune responses elicited by infection with Giardia responsible
for parasite clearance and sterilising immunity?
In some instances these infections are cleared spontaneously. However reinfection
of hosts frequently occurs (Farthing et al., 1986; Gilman et al., 1988). It is
not clear whether partial protective humoral immunity occurs in giardiasis. Reinfection
has been documented in infants and children (Farthing et al., 1986) as
well as in adults (Nash et al., 1987; Gilman et al., 1988), thus the issue of
immunological maturation with age cannot be used to explain the recurrent
infections in some individuals. In experimental human infections, re-infection was
confirmed as the volunteers were successfully treated after initial infections and
they were successfully re-challenged (Nash et al., 1987). In stUdies of the Giardiaspecific
immune response in infected human volunteers, serum immunoglobulins
19