SMALL-INTESTINAL INJURY IN A NEONATAL RAT MODEL OF GIARDIASIS IS STRAIN-DEPENDENT

Background and Aims: The factors that determine the severity of giardi asis are poorly understood. Host factors are important, but parasite v irulence may also play a role. The aim of this study was to compare th e apparent virulence of three genotypically different Giardia isolates (PO1, VNB3, and WB). Methods: infection rates, parasite loads, struct ural damage, disaccharidase activity, and water and electrolyte absorp tion were observed at 10 days after inoculation in a neonatal rat mode l of infection. Results: DNA fingerprinting showed differences between isolates studied. The infective rate varied between 67% and 100%. The m were no differences in intestinal parasite toad. infection with stra ins PO1 and WE, but not with VNB3, was associated with a reduction in villus height. There was precocious expression of sucrase at 10 days a fter inoculation in all infected groups. Water absorption of a plasma electrolyte solution was decreased in VNB3-infected animals when compa red with PO1- and WB-infected animals and controls. Water absorption a nd lactose hydrolysis were impaired during perfusion with a lactose-co ntaining solution in all infected groups. Conclusions: Three genotypic ally different Giardia isolates that infect neonatal rats with the sam e trophozoite load differ in their ability to cause functional mucosal damage. Infection with Giardia lamblia induced precocious expression of sucrase activity and impaired mucosal absorption.