FIG. 3.

(A) Parasites recrudesce independently of the pyrimethamine concentration. Fifty million parasitized erythrocytes (7% parasitemia) were exposed to the indicated concentrations of pyrimethamine for 4 days, washed, and returned to standard medium. Experiments were carried out in triplicate. Mean ± standard deviation levels of parasitemia and mean ± standard deviation durations from the day when treatment ceased until the day when the recrudescent parasitemia level reached or surpassed 1% are shown. The data are representative of three separate experiments. Means followed by the same letter were not significantly different (P = 0.744). (B) Recrudescent parasites showed the same pattern of sensitivity to pyrimethamine (PYR) as the parasites tested before treatment did.