The robustness of the weak selection approximation for the evolution of altruism against strong selection.

The weak selection approximation of population genetics has made possible the analysis of social evolution under a considerable variety of biological scenarios. Despite its extensive usage, the accuracy of weak selection in predicting the emergence of altruism under limited dispersal when selection intensity increases remains unclear. Here, we derive the condition for the spread of an altruistic mutant in the infinite island model of dispersal under a Moran reproductive process and arbitrary strength of selection. The simplicity of the model allows us to compare weak and strong selection regimes analytically. Our results demonstrate that the weak selection approximation is robust to moderate increases in selection intensity and therefore provides a good approximation to understand the invasion of altruism in spatially structured population. In particular, we find that the weak selection approximation is excellent even if selection is very strong, when either migration is much stronger than selection or when patches are large. Importantly, we emphasize that the weak selection approximation provides the ideal condition for the invasion of altruism, and increasing selection intensity will impede the emergence of altruism. We discuss that this should also hold for more complicated life cycles and for culturally transmitted altruism. Using the weak selection approximation is therefore unlikely to miss out on any demographic scenario that lead to the evolution of altruism under limited dispersal.

The spread of incompatibility-inducing parasites in sub-divided host populations.

BACKGROUND:Maternally transmitted symbionts have evolved a variety of ways to promote their spread through host populations. One strategy is to hamper the reproduction of uninfected females by a mechanism called cytoplasmic incompatibility (CI). CI occurs in crosses between infected males and uninfected females and leads to partial to near-complete infertility. CI-infections are under positive frequency-dependent selection and require genetic drift to overcome the range of low frequencies where they are counter-selected. Given the importance of drift, population sub-division would be expected to facilitate the spread of CI. Nevertheless, a previous model concluded that variance in infection between competing groups of breeding individuals impedes the spread of CI.RESULTS:In this paper we derive a model on the spread of CI-infections in populations composed of demes linked by restricted migration. Our model shows that population sub-division facilitates the invasion of CI. While host philopatry (low migration) favours the spread of infection, deme size has a non-monotonous effect, with CI-invasion being most likely at intermediate deme size. Individual-based simulations confirm these predictions and show that high levels of local drift speed up invasion but prevent high levels of prevalence across the entire population. Additional simulations with sex-specific migration rates further show that low migration rates of both sexes are required to facilitate the spread of CI.CONCLUSION:Our analyses show that population structure facilitates the invasion of CI-infections. Since some level of sub-division is likely to occur in most natural populations, our results help to explain the high incidence of CI-infections across species of arthropods. Furthermore, our work has important implications for the use of CI-systems in order to genetically modify natural populations of disease vectors.

Extensive natural variation for cellular hydrogen peroxide release is genetically controlled.

Natural variation in DNA sequence contributes to individual differences in quantitative traits. While multiple studies have shown genetic control over gene expression variation, few additional cellular traits have been investigated. Here, we investigated the natural variation of NADPH oxidase-dependent hydrogen peroxide (H(2)O(2) release), which is the joint effect of reactive oxygen species (ROS) production, superoxide metabolism and degradation, and is related to a number of human disorders. We assessed the normal variation of H(2)O(2) release in lymphoblastoid cell lines (LCL) in a family-based 3-generation cohort (CEPH-HapMap), and in 3 population-based cohorts (KORA, GenCord, HapMap). Substantial individual variation was observed, 45% of which were associated with heritability in the CEPH-HapMap cohort. We identified 2 genome-wide significant loci of Hsa12 and Hsa15 in genome-wide linkage analysis. Next, we performed genome-wide association study (GWAS) for the combined KORA-GenCord cohorts (n = 279) using enhanced marker resolution by imputation (>1.4 million SNPs). We found 5 significant associations (p<5.00×10-8) and 54 suggestive associations (p<1.00×10-5), one of which confirmed the linked region on Hsa15. To replicate our findings, we performed GWAS using 58 HapMap individuals and ∼2.1 million SNPs. We identified 40 genome-wide significant and 302 suggestive SNPs, and confirmed genome signals on Hsa1, Hsa12, and Hsa15. Genetic loci within 900 kb from the known candidate gene p67phox on Hsa1 were identified in GWAS in both cohorts. We did not find replication of SNPs across all cohorts, but replication within the same genomic region. Finally, a highly significant decrease in H(2)O(2) release was observed in Down Syndrome (DS) individuals (p<2.88×10-12). Taken together, our results show strong evidence of genetic control of H(2)O(2) in LCL of healthy and DS cohorts and suggest that cellular phenotypes, which themselves are also complex, may be used as proxies for dissection of complex disorders.

Subclinical hypothyroidism and the risk of coronary heart disease and mortality.

CONTEXT: Data regarding the association between subclinical hypothyroidism and cardiovascular disease outcomes are conflicting among large prospective cohort studies. This might reflect differences in participants' age, sex, thyroid-stimulating hormone (TSH) levels, or preexisting cardiovascular disease. OBJECTIVE: To assess the risks of coronary heart disease (CHD) and total mortality for adults with subclinical hypothyroidism. DATA SOURCES AND STUDY SELECTION: The databases of MEDLINE and EMBASE (1950 to May 31, 2010) were searched without language restrictions for prospective cohort studies with baseline thyroid function and subsequent CHD events, CHD mortality, and total mortality. The reference lists of retrieved articles also were searched. DATA EXTRACTION: Individual data on 55,287 participants with 542,494 person-years of follow-up between 1972 and 2007 were supplied from 11 prospective cohorts in the United States, Europe, Australia, Brazil, and Japan. The risk of CHD events was examined in 25,977 participants from 7 cohorts with available data. Euthyroidism was defined as a TSH level of 0.50 to 4.49 mIU/L. Subclinical hypothyroidism was defined as a TSH level of 4.5 to 19.9 mIU/L with normal thyroxine concentrations. RESULTS: Among 55,287 adults, 3450 had subclinical hypothyroidism (6.2%) and 51,837 had euthyroidism. During follow-up, 9664 participants died (2168 of CHD), and 4470 participants had CHD events (among 7 studies). The risk of CHD events and CHD mortality increased with higher TSH concentrations. In age- and sex-adjusted analyses, the hazard ratio (HR) for CHD events was 1.00 (95% confidence interval [CI], 0.86-1.18) for a TSH level of 4.5 to 6.9 mIU/L (20.3 vs 20.3/1000 person-years for participants with euthyroidism), 1.17 (95% CI, 0.96-1.43) for a TSH level of 7.0 to 9.9 mIU/L (23.8/1000 person-years), and 1.89 (95% CI, 1.28-2.80) for a TSH level of 10 to 19.9 mIU/L (n = 70 events/235; 38.4/1000 person-years; P <.001 for trend). The corresponding HRs for CHD mortality were 1.09 (95% CI, 0.91-1.30; 5.3 vs 4.9/1000 person-years for participants with euthyroidism), 1.42 (95% CI, 1.03-1.95; 6.9/1000 person-years), and 1.58 (95% CI, 1.10-2.27, n = 28 deaths/333; 7.7/1000 person-years; P = .005 for trend). Total mortality was not increased among participants with subclinical hypothyroidism. Results were similar after further adjustment for traditional cardiovascular risk factors. Risks did not significantly differ by age, sex, or preexisting cardiovascular disease. CONCLUSIONS: Subclinical hypothyroidism is associated with an increased risk of CHD events and CHD mortality in those with higher TSH levels, particularly in those with a TSH concentration of 10 mIU/L or greater.

Accelerated MR imaging with spread spectrum encoding

We advocate the use of a novel compressed sensing technique for accelerating the magnetic resonance image acquisition process, coined spread spectrum MR imaging or simply s2MRI. The method resides in pre-modulating the signal of interest by a linear chirp, resulting from the application of quadratic phase profiles, before random k-space under-sampling with uniform average density. The effectiveness of the procedure is theoretically underpinned by the optimization of the coherence between the sparsity and sensing bases. The application of the technique for single coil acquisitions is thoroughly studied by means of numerical simulations as well as phantom and in vivo experiments on a 7T scanner. The corresponding results suggest a favorable comparison with state-of-the-art variable density k-space under-sampling approaches.

Extensive variation at MHC DRB in the New Zealand sea lion (Phocarctos hookeri) provides evidence for balancing selection.

Marine mammals are often reported to possess reduced variation of major histocompatibility complex (MHC) genes compared with their terrestrial counterparts. We evaluated diversity at two MHC class II B genes, DQB and DRB, in the New Zealand sea lion (Phocarctos hookeri, NZSL) a species that has suffered high mortality owing to bacterial epizootics, using Sanger sequencing and haplotype reconstruction, together with next-generation sequencing. Despite this species' prolonged history of small population size and highly restricted distribution, we demonstrate extensive diversity at MHC DRB with 26 alleles, whereas MHC DQB is dimorphic. We identify four DRB codons, predicted to be involved in antigen binding, that are evolving under adaptive evolution. Our data suggest diversity at DRB may be maintained by balancing selection, consistent with the role of this locus as an antigen-binding region and the species' recent history of mass mortality during a series of bacterial epizootics. Phylogenetic analyses of DQB and DRB sequences from pinnipeds and other carnivores revealed significant allelic diversity, but little phylogenetic depth or structure among pinniped alleles; thus, we could neither confirm nor refute the possibility of trans-species polymorphism in this group. The phylogenetic pattern observed however, suggests some significant evolutionary constraint on these loci in the recent past, with the pattern consistent with that expected following an epizootic event. These data may help further elucidate some of the genetic factors underlying the unusually high susceptibility to bacterial infection of the threatened NZSL, and help us to better understand the extent and pattern of MHC diversity in pinnipeds.

Concentrations of the enantiomers of fluoxetine and norfluoxetine after multiple doses of fluoxetine in cytochrome P4502D6 poor and extensive metabolizers.

Plasma concentrations of the enantiomers of fluoxetine (FLX) and norfluoxetine (NFLX) were measured at days 7, 14, and 23 of oral administration of 20 mg of racemic fluoxetine in 11 patients who were comedicated with risperidone. Eight patients were genotyped as being cytochrome P4502D6 extensive metabolizers (EMs) and three as cytochrome P4502D6 poor metabolizers (PMs). No statistically significant differences were calculated between EMs and PMs in the concentrations of (R)-FLX and (R)-NFLX for all days examined (day 23, mean +/- SD for (R)-FLX and (R)-NFLX in EMs, 16 +/- 5 and 29 +/- 20 ng/mL, respectively; in PMs, 16 +/- 1 and 20 +/- 2 ng/mL, respectively). However, concentrations of (S)-FLX and (S)-NFLX were higher and lower, respectively, in PMs as compared with EMs (day 7, p = 0.037 and p = 0.036; day 14, p = 0.014 and p = 0.014; day 23, p = 0.068 and p = 0.038). On day 23, mean (S)-FLX and (S)-NFLX in EMs were (mean +/- SD) 39 +/- 26 and 63 +/- 26 ng/mL, and in PMs they were 88 +/- 7 and 19 +/- 2 ng/mL. This study confirms the results of the single-dose studies showing that CYP2D6 is involved in the demethylation of FLX to NFLX, with a stereoselectivity toward the (S)-enantiomer. The data also clearly show that the CYP2D6 genotype has an important influence on the concentrations of the (S)- but not of the (R)-enantiomer of FLX and NFLX after multiple doses.

Extracapsular tumor spread and the risk of local, axillary and supraclavicular recurrence in node-positive, premenopausal patients with breast cancer.

BACKGROUND: Extracapsular tumor spread (ECS) has been identified as a possible risk factor for breast cancer recurrence, but controversy exists regarding its role in decision making for regional radiotherapy. This study evaluates ECS as a predictor of local, axillary, and supraclavicular recurrence. PATIENTS AND METHODS: International Breast Cancer Study Group Trial VI accrued 1475 eligible pre- and perimenopausal women with node-positive breast cancer who were randomly assigned to receive three to nine courses of classical combination chemotherapy with cyclophosphamide, methotrexate, and fluorouracil. ECS status was determined retrospectively in 933 patients based on review of pathology reports. Cumulative incidence and hazard ratios (HRs) were estimated using methods for competing risks analysis. Adjustment factors included treatment group and baseline patient and tumor characteristics. The median follow-up was 14 years. RESULTS: In univariable analysis, ECS was significantly associated with supraclavicular recurrence (HR = 1.96; 95% confidence interval 1.23-3.13; P = 0.005). HRs for local and axillary recurrence were 1.38 (P = 0.06) and 1.81 (P = 0.11), respectively. Following adjustment for number of lymph node metastases and other baseline prognostic factors, ECS was not significantly associated with any of the three recurrence types studied. CONCLUSIONS: Our results indicate that the decision for additional regional radiotherapy should not be based solely on the presence of ECS.

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The pharmacokinetic profile of imatinib has been assessed in healthy subjects and in population studies among thousands of patients with CML or GIST. Imatinib is rapidly and extensively absorbed from the GI tract, reaching a peak plasma concentration (Cmax) within 1-4 h following administration. Imatinib bioavailability is high (98%) and independent of food intake. Imatinib undergoes rapid and extensive distribution into tissues, with minimal penetration into the central nervous system. In the circulation, it is approximately 95% bound to plasma proteins, principally α1-acid glycoprotein (AGP) and albumin. Imatinib undergoes metabolism in the liver via the cytochrome P450 enzyme system (CYP), with CYP3A4 being the main isoenzyme involved. The N-desmethyl metabolite CGP74588 is the major circulating active metabolite. The typical elimination half-life for imatinib is approximately 14-22 h. Imatinib is characterized by large inter-individual pharmacokinetic variability, which reflects in a wide spread of concentrations observed under standard dosage. Besides adherence, several factors have been shown to influence this variability, especially demographic characteristics (sex, age, body weight and disease diagnosis), blood count characteristics, enzyme activity (mainly CYP3A4), drug interactions, activity of efflux transporters and plasma levels of AGP. Additionally, recent retrospective studies have shown that drug exposure, reflected in either the area under the concentration-time curve (AUC) or more conveniently the trough level (Cmin), correlates with treatment outcomes. Increased toxicity has been associated with high plasma levels, and impaired clinical efficacy with low plasma levels. While no upper concentration limit has been formally established, a lower limit for imatinib Cmin of about 1000 ng/mL has been proposed repeatedly for improving outcomes in CML and GIST patients. Imatinib is licensed for use in chronic phase CML and GIST at a fixed dose of 400 mg once daily (600 mg in some other indications) despite substantial pharmacokinetic variability caused by both genetic and acquired factors. The dose can be modified on an individual basis in cases of insufficient response or substantial toxic effects. Imatinib would, however, meet traditional criteria for a therapeutic drug monitoring (TDM) program: long-term therapy, measurability, high inter-individual but restricted intra-individual variability, limited pharmacokinetic predictability, effect of drug interactions, consistent association between concentration and response, suggested therapeutic threshold, reversibility of effect and absence of early markers of efficacy and toxic effects. Large-scale, evidence-based assessments of drug concentration monitoring are therefore still warranted for the personalization of imatinib treatment.

Subclinical thyroid dysfunction and the risk of heart failure events: an individual participant data analysis from 6 prospective cohorts.

BACKGROUND: American College of Cardiology/American Heart Association guidelines for the diagnosis and management of heart failure recommend investigating exacerbating conditions such as thyroid dysfunction, but without specifying the impact of different thyroid-stimulation hormone (TSH) levels. Limited prospective data exist on the association between subclinical thyroid dysfunction and heart failure events. METHODS AND RESULTS: We performed a pooled analysis of individual participant data using all available prospective cohorts with thyroid function tests and subsequent follow-up of heart failure events. Individual data on 25 390 participants with 216 248 person-years of follow-up were supplied from 6 prospective cohorts in the United States and Europe. Euthyroidism was defined as TSH of 0.45 to 4.49 mIU/L, subclinical hypothyroidism as TSH of 4.5 to 19.9 mIU/L, and subclinical hyperthyroidism as TSH <0.45 mIU/L, the last two with normal free thyroxine levels. Among 25 390 participants, 2068 (8.1%) had subclinical hypothyroidism and 648 (2.6%) had subclinical hyperthyroidism. In age- and sex-adjusted analyses, risks of heart failure events were increased with both higher and lower TSH levels (P for quadratic pattern <0.01); the hazard ratio was 1.01 (95% confidence interval, 0.81-1.26) for TSH of 4.5 to 6.9 mIU/L, 1.65 (95% confidence interval, 0.84-3.23) for TSH of 7.0 to 9.9 mIU/L, 1.86 (95% confidence interval, 1.27-2.72) for TSH of 10.0 to 19.9 mIU/L (P for trend <0.01) and 1.31 (95% confidence interval, 0.88-1.95) for TSH of 0.10 to 0.44 mIU/L and 1.94 (95% confidence interval, 1.01-3.72) for TSH <0.10 mIU/L (P for trend=0.047). Risks remained similar after adjustment for cardiovascular risk factors. CONCLUSION: Risks of heart failure events were increased with both higher and lower TSH levels, particularly for TSH ≥10 and <0.10 mIU/L.

Développement de l'irrigation et évolution des régimes fonciers dans la région de Gaya (Niger)

Since the mid 90's, international actors as well as governmental actors have raised their interest into the development of irrigation's potential that is still largely unexploited in Niger. It seems all the more interesting as it could answer the needs of a fast growing population (3.3% per year). However, if everyone agrees on the need to development this system, the current implementation triggers questions on the process itself and its side effects. National and international policies on this matter were build upon an historical process through colonial, post-colonial and then the late 1980's neoliberal structures, leading to a business model that reveals a discrepancy between the state logic and the farming one. This business model asks for a high capacity of mobilization of resources unachievable for many, especially when they want to address small-scale irrigation (area extensive production of fruits and vegetables since the 1980's. These productions were developed at first by the local farmers, but the high value added engendered then attracted external players as well, such as civil servants and merchants. The World Bank supported this momentum through the development of a business type project. Unfortunately, it reached mostly the new external players and local elites rather than the small farmers, notably due to the high illiteracy rate among farmers. In terms of land tenure analysis, the project excluded all farmers cultivating land on a loan or lease agreement and all those for whom it was difficult to obtain a title of ownership. However, this new interest for small-scale irrigation exerted by the project and the new players triggered the commoditization of land. As a matter of fact, the demographic constraints and the fragmentation of the familial land ownership led to a more individual production system, where the customary relation to land tenure is weakened or even overcome. This makes it easier for the new players who need to settle their small-scale irrigation projects to purchase land. When there are only few areas available for selling, the. purchasing processes are undermining the farmers with insecure rights. If the withdrawal of lands is supposed to be smoothened by social measures, such as replacement of the land and primary offers to purchase the land, those measures are often not attractive. The proposed land of replacement is frequently too far away located or lesser fertile to be of any use and the economic capacity of purchasing is too little, eventually leading the farmers to leave their terroirs. Those in charge of the application of the Rural Code have succeeding in answering the need of written secured land tenure, but have difficulty to meet the challenge of doing the same to secure rights for farmers with loans or lease agreements. The small-scale irrigation could bring an answer for their financial needs to buy the land, but it would require mobilizing resources to invest or an easier access to supportive projects. The economic benefice from small-scale irrigation is now widely recognized, but we have to take also into account the risks of marginalization of part of the small farmers. For a more widely spread exploitation of small-scale irrigation, the mechanism of land regulation as well as the process to access the financial and technical support of projects must be revised in order to reach more small farmers. Développement de l'irrigation et évolution des régimes fonciers dans la région de Gaya (Niger) - Le secteur de l'irrigation a bénéficié d'un regain d'intérêt de la part des acteurs internationaux du développement et de l'Etat nigérien depuis le milieu des années 1990. Cet intérêt est à la hauteur du potentiel en terres irrigables (300Ό00 ha environ) du pays, largement sous-exploité alors que les besoins alimentaires sont grandissants, la population augmentant de 3.3% par an. Si le diagnostic est correct, les stratégies mises en oeuvre en matière d'irrigation posent question. Les interventions, aussi bien publiques qu'internationales, reposent sur un modèle entrepreneurial qui parachève une longue trajectoire historique. Initiée par l'Etat colonial, poursuivie par l'Etat post-colonial et transformé par les politiques néolibérales des années 1980, elle se caractérise par un hiatus constant entre logiques étatiques et logiques paysannes. En matière de petite irrigation privée (surfaces < 1-2 ha, technologies à faible coût), ce modèle présuppose une mobilisation de ressources (économiques, sociales, éducationnelles et foncières) inégalement réparties au sein de la population rurale. Cette recherche s'est intéressée à expliciter les liens qui existent entre le développement de la petite irrigation privée et l'évolution des régimes fonciers. Les trois questionnements qui ont guidé l'analyse empirique portent sur la sécurisation foncière, les dynamiques de marchandisation de la terre et l'accès à la terre pour tous les producteurs. Le Département de Gaya dispose d'un potentiel très important en ressources hydriques, facilement mobilisables. Les productions maraîchères et fruitières ont connu un essor très important à partir des années 1980. Initialement pratiquées par les cultivateurs, elles ont progressivement attiré l'attention d'acteurs externes au monde rural (fonctionnaires, commerçants), du fait de leur haute valeur ajoutée. La Banque mondiale a fortement soutenu cette dynamique à travers un projet à vocation entrepreneuriale, qui s'est pourtant révélé hors de portée de la majorité des petits paysans et a principalement bénéficié à ces acteurs extra-ruraux ainsi qu'à certaines élites locales. Au plan foncier, il a en particulier exclu tous les emprunteurs des terres, qui ne sont pas à même de produire des documents écrits confirmant leurs droits sur la terre. Ce projet, et plus largement l'intérêt que les acteurs extra-ruraux portent à la petite irrigation, ont contribué à alimenter la marchandisation de la terre. Sans ancrage familial dans les terroirs villageois, ces acteurs sont obligés d'acheter la terre pour faire de l'irrigation. Leur demande vient s'inscrire dans un contexte général où la pression démographique et le morcellement successif des capitaux fonciers familiaux ont progressivement individualisé la relation entre les producteurs et la terre, au point d'affaiblir ou de faire tomber les interdits coutumiers en matière de vente. Dans les espaces disposant de faibles réserves foncières, les ventes se font principalement au détriment des acteurs qui, comme les emprunteurs, disposent de droits fonciers peu stables et sécurisés. Si le retrait de la terre est socialement encadré (terre en remplacement, possibilité d'acheter la terre qui va être vendue), il pose également des contraintes agronomiques (sols de moindre qualité) et économiques (nécessité de disposer des liquidités pour racheter la terre) qui peuvent, en dernier ratio, obligent les acteurs concernés à quitter les terroirs. Les instances du Code rural, qui ont su apporter des réponses satisfaisantes à la demande de sécurisation foncière par l'établissement de documents écrits, rencontrent aujourd'hui de grandes difficultés à en faire de même pour les droits de prêt. Dans ce contexte, l'irrigation peut apporter les sommes nécessaires à l'achat des terres. Encore faut-il que ces emprunteurs disposent des ressources financières propres pour la développer ou qu'ils puissent y avoir accès grâce à l'appui d'un projet. Si l'intérêt économique de la petite irrigation privée est indiscutable, les risques de marginalisation d'une partie de producteurs ruraux qu'elle peut produire sont bien réels. Pour en faire une activité accessible au plus grand nombre, il faut revoir les mécanismes de régulation foncière, ainsi que les montages techniques et financiers qui supportent le développement de ce secteur d'activité très prometteur.

Residual antimalarials in malaria patients from Tanzania--implications on drug efficacy assessment and spread of parasite resistance.

Repeated antimalarial treatment for febrile episodes and self-treatment are common in malaria-endemic areas. The intake of antimalarials prior to participating in an in vivo study may alter treatment outcome and affect the interpretation of both efficacy and safety outcomes. We report the findings from baseline plasma sampling of malaria patients prior to inclusion into an in vivo study in Tanzania and discuss the implications of residual concentrations of antimalarials in this setting. In an in vivo study conducted in a rural area of Tanzania in 2008, baseline plasma samples from patients reporting no antimalarial intake within the last 28 days were screened for the presence of 14 antimalarials (parent drugs or metabolites) using liquid chromatography-tandem mass spectrometry. Among the 148 patients enrolled, 110 (74.3%) had at least one antimalarial in their plasma: 80 (54.1%) had lumefantrine above the lower limit of calibration (LLC = 4 ng/mL), 7 (4.7%) desbutyl-lumefantrine (4 ng/mL), 77 (52.0%) sulfadoxine (0.5 ng/mL), 15 (10.1%) pyrimethamine (0.5 ng/mL), 16 (10.8%) quinine (2.5 ng/mL) and none chloroquine (2.5 ng/mL). The proportion of patients with detectable antimalarial drug levels prior to enrollment into the study is worrying. Indeed artemether-lumefantrine was supposed to be available only at government health facilities. Although sulfadoxine-pyrimethamine is only recommended for intermittent preventive treatment in pregnancy (IPTp), it was still widely used in public and private health facilities and sold in drug shops. Self-reporting of previous drug intake is unreliable and thus screening for the presence of antimalarial drug levels should be considered in future in vivo studies to allow for accurate assessment of treatment outcome. Furthermore, persisting sub-therapeutic drug levels of antimalarials in a population could promote the spread of drug resistance. The knowledge on drug pressure in a given population is important to monitor standard treatment policy implementation.