Recent advances in the diagnosis and management of giardiasis.

Management of patients with giardiasis is often difficult because of problems related to diagnosis, lack of knowledge about pathophysiology, and a less than satisfactory chemotherapeutic armamentarium. Treatment, particularly in children, presents several problems: What drug should be used, and at what dosage? Should the patient's contacts be treated? How does one cope with treatment failures? An overview of data available in the literature is presented, and studies on the susceptibility and resistance of Giardia isolates to different drugs in in vitro and in vivo models are discussed. In such models, tinidazole, metronidazole, and furazolidone were most active in terms of susceptibility; quinacrine was least active. However, Giardia strains resistant to all four drugs were isolated. Nitroimidazoles were associated with poor compliance in children, whereas furazolidone was well tolerated. It is concluded that management of symptomatic giardiasis is complicated by a range of factors, including drug resistance, patient compliance, and the lack of an accurate, sensitive, and noninvasive diagnostic test.