There were no IgA antibodies to Giardia heat shock antigen, however, in any of these children with chronic infection.

Sera from all patients contained IgG antibodies that recognised Giardia heat shock antigen.

In addition, these patients with chronic infection unlike those who clear the infection have no IgA response to Giardia heat shock antigen.

The present study has highlighted a difference in the serum IgA response to a Giardia antigen,Giardia heat shock antigen in acute and chronic infection.

The aims of the present study were to characterise the antibody response to Giardia in these children and to investigate the significance of antibodies to Giardia heat shock antigen in chronic infection.

The absence of specific Iga response to Giardia heat shock antigen in patients with chronic infection suggests that the development of IgA antibodies to this antigen may be an important factor determining parasite clearance.