Comparison of Artemether-Lumefantrine with Sulfadoxine-Pyrimethamine for the Treatment of Uncomplicated Falciparum Malaria in Eastern Nepal Suman Thapa, Judith Hollander, Mary Linehan, Janet Cox-Singh, Mahendra B. Bista, Garib D. Thakur, Wendy A. Davis, and Timothy M. E. Davis* Sukraraj Tropical and Infectious Disease Hospital, Kathmandu, Nepal; Research Triangle Institute International, Kathmandu, Nepal; Research Triangle Institute International, Washington, DC; University Malaysia Sarawak, Malaria Research Centre, Faculty of Medicine and Health Sciences, Kuching, Sarawak, Malaysian Borneo; Nepal Government, Ministry of Health and Population, Department of Health Services, Epidemiology and Disease Control Division, Kathmandu, Nepal; University of Western Australia, School of Medicine and Pharmacology, Fremantle Hospital, Fremantle, Australia Abstract. Because available data suggest that resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine (SP) is increasing in Nepal, an open-label, parallel-group efficacy/safety study was conducted in 99 Nepalese patients with uncomplicated falciparum malaria randomized 2:1 to artemether-lumefantrine (AL) or SP. Efficacy was assessed from clinical and microscopic evidence of treatment failure. Four SP-treated patients (12.1%; 95% CI, 4.0–29.1%) redeveloped parasitemia during the 28-day follow-up versus 0% (95% CI, 0–6.9%) in the AL group (P  0.011), a difference that was confirmed by polymerase chain reaction (PCR) analysis of parasite DNA. PCR detected an addi- tional six patients (two SP and four AL) with sub-microscopic gametocytemia or breakthrough parasitemia between Days 14 and 28, suggesting that AL efficacy was lower than estimated by microscopy. Dhfr and dhps mutations were not associated with outcome. AL is more effective than SP for uncomplicated malaria in Nepal, but regular monitoring of its efficacy should be carried out if this combination therapy is introduced. Although mosquito vectors cannot survive at high altitude in mountainous regions of Nepal, malaria transmission occurs in the lower-lying areas of the Terai in the south of the coun- try. 1 Over the last 20 years, the annual incidence of malaria in Nepal has varied between 0.4 and 3.6/1,000 people, with Plas- modium falciparum accounting for up to 20% of cases. 2 Ap- proximately 80% of total cases and > 90% of those of falci- parum malaria occur in 12 districts that share a border with India. 3 These districts contain ∼6 million people, a figure ap- proaching one quarter of the country’s population. 3 Parasite resistance to conventional antimalarial drugs has emerged in Nepal. High levels of chloroquine resistance re- sulted in a change in first-line antimalarial therapy to sulfa- doxine-pyrimethamine (SP) in 1989, but limited data suggest that SP resistance now varies between 56% and 87%. 3 The most detailed studies have been carried out in the Jhapa dis- trict in the southeast of the country, 1 of the 12 districts with relatively high transmission, including a significant proportion of cases of falciparum malaria. In a clinical study conducted in Jhapa in 2003–2004, 4 the failure rate for SP treatment of fal- ciparum malaria was 21% at 28 days by World Health Orga- nization (WHO) criteria. 5,6 This finding is consistent with an in vitro study done in the same area in 2002, which showed that the C59R and S108N mutations in P. falciparum dihy- drofolate reductase (dhfr) were nearly universal, whereas triple mutations (N51I, C59R, and S108N) were found in 10% of isolates. 7 As a response to the antimalarial drug resistance situation, the WHO now supports the use of artemisinin-based combi- nation therapy (ACT) in countries such as Nepal. 8 The rec- ommended first-line ACT is artemether-lumefantrine (AL). 8 In light of this recommendation, failing SP effectiveness in the Terai, and the need for data to inform national antimalarial drug policy in Nepal and other countries in a similar epide- miologic situation, we conducted a detailed study of SP and AL therapy in the Jhapa District with the primary aim of comparing the efficacy of the two treatments. Secondary aims were to 1) assess whether there are age-associated differences in the response to either regimen, 2) relate clinical and para- sitologic treatment failure after SP therapy to parasite dhfr and dihydropteroate synthetase (dhps) mutations, 3) docu- ment the effect of the two regimens on gametocyte carriage and thus their potential influence on transmission, and 4) determine, through the use of polymerase chain reaction (PCR) analysis of parasite DNA in all follow-up blood samples, whether there are submicroscopic recrudescences that might be the forerunners of clinically significant parasite resistance. MATERIALS AND METHODS Study design, timelines, approval, and registration. This study was an open-label, randomized, parallel-group efficacy and safety study that was carried out during the rainy season months of August, September, and October 2005. Given the availability of recent SP efficacy data from the Jhapa dis- trict 4–6 and the lack of AL efficacy data, treatment was by sequential allocation in the ratio of two AL cases to one SP case. Under this design, a total of at least 99 patients was needed to show a 28-day cure rate for SP (75%) 5,6 that was 20% less than that for AL (95%) 8 at 80% power and P < 0.05. 9 The study was approved by the Nepal Health Research Council, registered with the Australian Clinical Trials Regis- try (ACTRN012605000551695), and conducted in accordance with the Helsinki Declaration. Patients. We recruited patients > 5 years of age and of either sex who had 1) uncomplicated falciparum or mixed falciparum/vivax malaria infection based on absence of WHO criteria for severity, 10 2) a P. falciparum asexual parasite den- sity > 500/L whole blood, 3) no history of antimalarial treat- ment within the previous month, and 4) an axillary tempera- ture > 37.5°C and/or history of fever within the previous 3 days. Exclusion criteria included 1) body weight < 10 kg, 2) pregnancy, and 3) co-incident severe non-malarial illness. All * Address correspondence to Timothy M. E. Davis, School of Medi- cine and Pharmacology, Fremantle Hospital, PO Box 480, Fremantle, Western Australia 6959, Australia. E-mail: tdavis@cyllene.uwa .edu.au Am. J. Trop. Med. Hyg., 77(3), 2007, pp. 423–430 Copyright © 2007 by The American Society of Tropical Medicine and Hygiene 423