Parasitemia, hematocrit, and reticulocyte percentage of

P falciparum–infected Aotus monkeys over the course of infection. (A) Group 1: monkeys did not develop a microscopically detectable parasitemia, did not become anemic, and reticulocyte production remained low and steady in most cases (eg, Aotus 603), with some exceptions (eg, Aotus 732). (B) Group 2: monkeys did not develop a microscopically detectable parasitemia but were positive by PCR, developed severe anemia (hematocrit less than 25%), and reticulocyte production stopped. Reticulocyte production and hematocrit level greatly increased after parasites were cleared by drug cure (eg, Aotus 676 and 2611). (C) Group 3: monkeys developed low-level (below 5%) to undetectable parasitemia positive by PCR, became moderately anemic, and reticulocyte production greatly decreased. Monkeys were able to self-resolve the infection and the anemia with increased reticulocyte production once parasites were cleared (eg, Aotus 560). (D) Group 4: monkeys developed low-level parasitemia, became severely anemic, and reticulocyte production decreased. Reticulocyte production and hematocrit level greatly increased after parasites were cleared by drug cure (eg,Aotus 604). Individual examples shown here are representative of the group. ± indicates PCR positive/negative forP falciparum DNA; arrow, antimalaria drug cure administered to monkey. All untreated monkeys received antimalarial drug cure on day 29, the last day of the trial. Numbers in graphs, reticulocyte percentage, taken on days 7, 14, 21, 29, and 36.