In giardiasis malabsorption is due to all except:

The reasons that some, but not all, infected patients develop clinical manifestations and the mechanisms by which Giardia causes alterations in small-bowel function are largely unknown. Although trophozoites adhere to the epithelium, they do not cause invasive or locally destructive alterations. The lactose intolerance and, in a minority of infected adults and children, significant malabsorption that develop are clinical signs of the loss of brush-border enzyme activities. In most infections, the morphology of the bowel is unaltered; however, in a few cases (usually in chronically infected, symptomatic patients), the histopathologic findings (including flattened villi) and the clinical manifestations resemble those of tropical sprue and gluten-sensitive enteropathy. The natural history of Giardia infection varies markedly. Infections may be aboed, transient, recurrent, or chronic. Parasite as well as host factors may be impoant in determining the course of infection and disease.