Giardiasis: Pathogenicity

In many cases infection is asymptomatic, but some patients develop symptoms. One hypothesis as to the pathogenicity is the mechanical covering of the intestinal epithelium (see above). This is not, however, the only way in which the parasite gives rise to symptoms. Giardia is cytopathogenic on cell monolayers in vitro. Probably there is also in-vivo enterocytic damage with secondary disaccharidase (lactase) deficiency. Indeed, villous atrophy is found in patients. Another way in which Giardia may be pathogenic, is the destruction of conjugated bile salts with secondary steatorrhoea. Yet another unanswered question is whether the immune response contributes to the pathogenesis. In vivo Giardia has frequent endosymbiotic bacteria up to 100 per trophozoite. This may possibly influence pathogenicity. The same question arises as regards any ectosymbionts.

Category: Medicine Notes