the research was conducted at 4 islands on lake victoria ( kibuogi , ngodhe , takawiri , mfangano ) and 1 shoreline community of mbita district ( ungoye ) in western kenya ( figure ) . in this area , the pfpr210 ( community p. falciparum parasite rate standardized to the 2- to 10-year age group ) although in some area of kenya malaria has decreased , its prevalence remains high in the lake victoria basin because of the lake environment ( 810 ) . in 2009 , a total of 50%70% of households owned insecticide - treated bed nets ( 11 ) , which substantially reduce the risk for transmission of malaria parasites by providing barriers against mosquitoes . june and october  november ) ( 9 ) , in the study sites , it is highly endemic throughout the year . study sites for investigation of k13 propeller gene in plasmodium falciparum , mbita district , kenya , 20122013 . filter paper blood spots were collected from participants ( technical appendix table 1 ) during population - wide cross - sectional malaria surveys conducted in february and august 2012 and august 2013 at the 5 study sites . parasitic dna was extracted from the filter paper ( 12 ) , and p. falciparum dna was detected by a mitochondrial dna - based pcr ( 13 ) . sequencing of the k13 propeller gene was attempted on the diagnostic pcr - positive specimens ( online technical appendix ) . the prevalence of p. falciparum , as determined by pcr , in the rainy and dry seasons was 7.2%26.2% and 6.5%15.5% on the 3 small islands ( kibuogi , ngodhe , and takawiri ) , 47.3% and 31.4% on mfangano island , and 38.4% and 41.9%64.0% in ungoye , respectively ( table 1 ) . * nine new types of point mutations were identified among these samples ( table 2 ) . participants infected with parasites harboring a mutation on the k13 propeller gene are listed in technical appendix table 2 . the sequences reported in this study have been deposited in the ddbj / embl / genbank databases ( accession nos.ab936059ab936067 ) . we detected 4 novel nonsynonymous and 5 novel synonymous mutations in the highly conserved k13 propeller gene of p. falciparum parasites from western kenya . noted that the frequency of mutant alleles strongly correlated with the prevalence of day 3 positivity after act treatment in humans in cambodia and that those mutations reflected positive selection ( 6 ) . that study found 17 mutant alleles in the k13 propeller gene . among them , c580y , r539 t , and y493h were prevalent and strongly related to in vivo delayed parasite clearance . in our study , all the mutations found differed from those reported in cambodia , and mutant alleles were not always observed in the proceeding seasons , so some mutations could be occasionally introduced . most of those mutations are not suitable for the life cycle of parasites , and only a few suitable for survival under the conditions of artemisinin selection pressure could be selected . furthermore , only 1 type of mutation , a578s from mfangano island , was detected during 2 seasons , whereas other mutations were not observed in the next season , half a year later . any family relations were not identified among the 4 participants harboring a578s mutation in february 2012 at mfangano island . point mutations can occasionally occur on the p. falciparum k13 propeller gene as a standing variation , but most of the isolates that recently acquired the mutation may disappear because of some fitness disadvantage or the effect of a random genetic drift ( 14 ) . we detected the mutant allele a578s in the k13 propeller gene in 2 consecutive seasons on mfangano island . this mutation , which modifies amino acids from being hydrophobic to hydrophilic , is close to the prevalent single nucleotide polymorphism c580y from cambodia that is thought to be necessary in protein  protein interactions , which could affect artemisinin susceptibility . the genotype analyses of the parasites from this island are critical to understanding the role of this mutation and act efficiency in this geographic area . our k13 propeller sequence analysis of p. falciparum parasites from a malaria - endemic area in kenya did not detect the predicted artemisinin - resistant genotypes , but we observed some temporal substitutions . a limitation of our study was that the sample size was insufficient to specifically provide an understanding of this result . the accumulation of data from this region and from other malaria - endemic areas will increase our understanding of the relationship between the k13 propeller gene and artemisinin resistance . monitoring these molecular markers and the efficacy of antimalarial drugs is critical for increasing understanding of artemisinin resistance and predicting its spread . demographic information about the study participants ; sequencing of the plasmodium falciparum k13 propeller gene ; and data on the participants who had parasites harboring a mutation on the k13 propeller gene .