Resistance of Plasmodium falciparum to amodiaquine in Papua New Guinea.

The sensitivity of Plasmodium falciparum to amodiaquine was assessed in children in the Madang region of Papua New Guinea. Fifty-four tests in vivo were carried out and 19 (35%) of these showed resistance at the RII or RIII level. Twenty-two of the 43 isolates tested showed some degree of resistance to amodiaquine in vitro. A negative correlation between the age of the patient and apparent resistance of the parasite in vivo was observed. There was no correlation between resistance in vivo and in vitro.