Estimates were made of the number of Giardia in 1,090 stools from 15 infected children over periods of 1 to 3 months. Three patterns of excretion were observed: 1) high, with the parasite abundant in nearly all stools; 2) low, with the parasite detectable in only 40% of stools and scanty when present; and 3) mixed, with periods of 1 to 3 weeks of high excretion alternating with generally shorter periods of low excretion, and an overall average of about 60% of stools positive. The presence and relative numbers of Giardia in the feces apparently were unrelated to either the consistency of the stools or frequency of defecation. Attempts to increase parasite excretion with purgatives were, on the whole, unsuccessful.
Fellow of the ICMR Research Associate Program (IRAP). Present address: Department of Public Health, County of San Diego, 1600 Pacific Highway, San Diego, California 92101.
Research Associate, Department of Pediatrics, Universidad del Valle, Cali, Colombia.