Modelling the development of resistance of Plasmodium falciparum to anti-malarial drugs.

A hybrid transmission/genetics model for the development of resistance by Plasmodium falciparum to anti-malarial drugs is set forth. Field data on pyrimethamine resistance are used to calibrate and test the model. Simulated consequences of different drug dosage and population coverage strategies are presented to illustrate an ethical dilemma. A strategy of maximally effective treatment for all infected individuals in the short term can be deleterious--in terms of rapid development of drug resistance--for a community in the longer term.