Molecular Pathogenesis of Giardia lamblia: Adherence and Encystation

  • Gerald T. Keusch
  • Honorine D. Ward
  • Eduardo Ortega-Barria
  • Norma Galindo
  • Miercio E. A. Pereira
Part of the Federation of European Microbiological Societies Symposium Series book series (FEMS, volume 58)


Giardia lamblia, a non invasive protozoan pathogen of the human small bowel, causes a spectrum of infection ranging from asymptomatic carriage, through acute watery diarrhea, to chronic diarrhea and malabsorption. Giardia has a simple life cycle, existing in just two forms, the multiplying trophozoite which infects mammalian hosts to cause disease, and the environmentally resistant cyst which serves in the transmission of infection from host to host. Efforts to understand disease pathogenesis and control infection therefore focus on the cell biology of the trophozoite, whereas public health interests target the process of encystation and the potential for control of spread. There are at least three clearly discernible steps in pathogenesis, once the cyst has been ingested and excystation has been triggered by a drop of pH in the stomach. First, the trophozoite has to colonize the small intestinal mucosal surface, second it may disrupt the normal physiology of the gut and produce intestinal symptoms such as diarrhea and malabsorption, and third, it must transform into the cyst in order to reach the external environment and propagate the species.


Wheat Germ Agglutinin Lectin Activity Rabbit Erythrocyte Giardia Lamblia Public Health Interest 
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Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • Gerald T. Keusch
    • 1
  • Honorine D. Ward
    • 1
  • Eduardo Ortega-Barria
    • 1
  • Norma Galindo
    • 1
  • Miercio E. A. Pereira
    • 1
  1. 1.Geographic Medicine and Infectious DiseasesNew England Medical CenterBostonUSA

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