Giardia and Giardiasis
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It is over 10 years since Meyer and Radulescu (1979) reviewed Giardia and giardiasis in Advances in Parasitology. In their introduction, they emphasized that "despite their ubiquity and antiquity, the Giardia have, until recently, been little studied". In the intervening years, Giardia has been extensively studied. The number of papers published has increased enormously, two books on the parasite have been produced (Erlandsen and Meyer, 1984; Meyer, 1990a), and an international conference on Giardia has been organized (Wallis and Hammond, 1988). Yet it is still very difficult to keep up with developments in this productive field of research and, despite all these research efforts, several fundamental questions concerning Giardia and giardiasis remain unresolved (Table 1), particularly with respect to the relationship of Giardia and disease, and the role of zoonotic transmission. Indeed, it is only recently that we have started to appreciate the clinical significance of Giardia infections in developing countries and among disadvantaged groups. Giardia is now recognized as one of the 10 major parasites of humans, being equal to ascariasis as a cause of death in the developing world (Warren, 1989; Meyer, 1990b). In developed countries, Giardia has the distinction of being the most commonly reported human intestinal parasite (Acha and Szyfres, 1987; Thompson et al., 1990a; Schantz, 1991). Regrettably, however, the range of drugs available to treat giardiasis is limited and their efficacy leaves much to be desired. There is an urgent need for new antigiardial agents, yet this search is hampered by our lack of understanding of many fundamental aspects of Giardia biochemistry and metabolism. In addition, although the application of molecular biological techniques to research on Giardia has revealed new avenues of investigation, it has also given rise to many new questions about this intriguing organism concerning its phylogenetic position, reproductive behaviour and genetic diversity.
To review Giardia and giardiasis in detail would require at least an entire volume of Advances in Parasitology. Such treatment in depth is not warranted at this time in view of the excellent book recently edited by Meyer (1990a). Our intention here is to give an up-to-date overview of Giardia and giardiasis and provide an insight into the enormous wealth of literature on the subject, as well as highlight the most important recent developments and unresolved questions.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Veterinary Studies|
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