Bouza, M., Maciques, I., Torres, D., and Núnez, FA 2000. Giardia during an 18-month period and all the stool specimens were examined lamblia in mongolian gerbils: Characteristics of infection using differ- for the presence of parasites by direct wet mount and formalin–ether ent human isolates. Experimental Parasitology 96, 43–46. 2000 concentration techniques. Clinical findings,(see Table I) were taken Academic Press from the Day Care Center (DCC) personal clinical record of each child. Giardia lamblia constitutes a public health problem in many coun- The seven isolates were taken from two children who were positive tries. This flagellated protozoan found in the small intestine of humans in all cross-sectional surveys (), one child who was positive develops a wide clinical spectrum, varying from none in asymptomatic three times (), three other children who were positive twice carriers to long-standing diarrhea and malabsortion in symptomatic(), and one child who was positive only once (). All children persons (Domenech et al. 1991; Mahmud et al. 1995). Studies from were between 2 and 4 years old (mean 2.14 years). In each crossthe last decade have shown differences among isolates with respect to sectional survey all the infected children were treated with metronidaisoenzyme patterns, genetic characterization, and antigenic composizole (Khaw and Panosian 1995) at a dose of 35 mg/kg of body weight tion (Upcroft et al. 1995; Vankeulen et al. 1995; Guimaraes et al. per day, divided into three subdoses, over 10 days, by the DCC at-1999), and they could explain the differences in virulence of the parasite tending physician. and the clinical variability of this infection in humans. The animals used in the experiments were 6-to 10-week-old male