Wanida IttaratAmy L. PickardPanthip RattanasinganchanPolrat WilairatanaSornchai LooareesuwanKathryn EmeryJonathan LowRachanee UdomsangpetchSteven R. MeshnickMahidol UniversityThe University of North Carolina at Chapel HillUniversity of Michigan School of Public HealthBox 09442018-07-242018-07-242003-02-01American Journal of Tropical Medicine and Hygiene. Vol.68, No.2 (2003), 147-152000296372-s2.0-0037313684https://repository.li.mahidol.ac.th/handle/20.500.14594/20931Artemisinin derivatives are first-line antimalarial drugs in Thailand. No firm evidence of clinically relevant artemisinin resistance exists. When used as monotherapy, artesunate has been associated with a high treatment failure (recrudescence) rate, which could be due to low-level artemisinin resistance. To understand the causes of recrudescence, we retrospectively studied a cohort of 104 malaria patients treated with artesunate monotherapy, 32 of whom recrudesced. There was no difference in in vitro artesunate sensitivities between 6 nonrecrudescent isolates and 16 paired admission and recrudescent isolates. Paired admission and recrudescent isolates from 10 patients were genotyped; only 3 had pfmdr1 mutations. Patients with admission parasitemias >10,000 per μl had a 9-fold higher likelihood of recrudescence (adjusted odds ratio) compared with patients with lower parasitemias. This study suggests (1) recrudescence after treatment with artesunate is not the result of inherent parasite resistance, and (2) admission parasitemia may be useful in choosing therapeutic options.Mahidol UniversityImmunology and MicrobiologyArticleSCOPUS