Plasmodium falciparum dihydrofolate reductase alleles and pyrimethamine use in pregnant Ghanaian women

Drug resistance in Plasmodium falciparum affects prevention of malaria in p regnancy. In a cross-sectional study of 530 pregnant Ghanaian women, P. fal ciparum dihydrofolate reductase (DHFR) gene mutations linked with pyrimetha mine resistance were assessed and associations with pyrimethamine intake we re analyzed. P. falciparum infected 69% of women without pyrimethamine use, 59% of those who had a history of pyrimethamine consumption but a negative urine test, and 53% of individuals with a positive urine test. Eighty-one percent, 43%, and 74% of the isolates contained the mutations Asn-108, Ile- 51, and Arg-59, respectively. Thr-108 occur-red in 8%. Pyrimethamine use wa s associated with increased frequencies of Asn-108 and Arg-59 but not of Il e-51 or Thr-108. In women with prophylaxis, wild-type parasites were absent and anemia tended to be more common with an increasing number of DHFR gene mutations. Pyrimethamine appears to be not adequately effective in this pa rt of Ghana, most likely due to the predominance of resistant parasites. Se lection for resistance following insufficient prophylaxis could possibly af fect the efficacy of future intermittent sulfadoxine-pyrimethamine treatmen t.