Little Polymorphism at the K13 Propeller Locus in Worldwide Plasmodium falciparum Populations Prior to the Introduction of Artemisinin Combination Therapies.

The emergence and spread of artemisinin-resistant Plasmodium falciparum is of huge concern for the global effort toward malaria control and elimination. Artemisinin resistance, defined as a delayed time to parasite clearance following administration of artemisinin, is associated with mutations in the Pfkelch13 gene of resistant parasites. To date, as many as 60 nonsynonymous mutations have been identified in this gene, but whether these mutations have been selected by artemisinin usage or merely reflect natural polymorphism independent of selection is currently unknown. To clarify this, we sequenced the Pfkelch13 propeller domain in 581 isolates collected before (420 isolates) and after (161 isolates) the implementation of artemisinin combination therapies (ACTs), from various regions of endemicity worldwide. Nonsynonymous mutations were observed in 1% of parasites isolated prior to the introduction of ACTs. Frequencies of mutant isolates, nucleotide diversity, and haplotype diversity were significantly higher in the parasites isolated from populations exposed to artemisinin than in those from populations that had not been exposed to the drug. In the artemisinin-exposed population, a significant excess of dN compared to dS was observed, suggesting the presence of positive selection. In contrast, pairwise comparison of dN and dS and the McDonald and Kreitman test indicate that purifying selection acts on the Pfkelch13 propeller domain in populations not exposed to ACTs. These population genetic analyses reveal a low baseline of Pfkelch13 polymorphism, probably due to purifying selection in the absence of artemisinin selection. In contrast, various Pfkelch13 mutations have been selected under artemisinin pressure.

The effect of mobile phone text-message reminders on Kenyan health workers' adherence to malaria treatment guidelines: a cluster randomised trial.

BACKGROUND: Health workers' malaria case-management practices often differ from national guidelines. We assessed whether text-message reminders sent to health workers' mobile phones could improve and maintain their adherence to treatment guidelines for outpatient paediatric malaria in Kenya. METHODS: From March 6, 2009, to May 31, 2010, we did a cluster-randomised controlled trial at 107 rural health facilities in 11 districts in coastal and western Kenya. With a computer-generated sequence, health facilities were randomly allocated to either the intervention group, in which all health workers received text messages on their personal mobile phones on malaria case-management for 6 months, or the control group, in which health workers did not receive any text messages. Health workers were not masked to the intervention, although patients were unaware of whether they were in an intervention or control facility. The primary outcome was correct management with artemether-lumefantrine, defined as a dichotomous composite indicator of treatment, dispensing, and counselling tasks concordant with Kenyan national guidelines. The primary analysis was by intention to treat. The trial is registered with Current Controlled Trials, ISRCTN72328636. FINDINGS: 119 health workers received the intervention. Case-management practices were assessed for 2269 children who needed treatment (1157 in the intervention group and 1112 in the control group). Intention-to-treat analysis showed that correct artemether-lumefantrine management improved by 23·7 percentage-points (95% CI 7·6-40·0; p=0·004) immediately after intervention and by 24·5 percentage-points (8·1-41·0; p=0·003) 6 months later. INTERPRETATION: In resource-limited settings, malaria control programmes should consider use of text messaging to improve health workers' case-management practices. FUNDING: The Wellcome Trust.

Indigenous evolution of Plasmodium falciparum pyrimethamine resistance multiple times in Africa.

OBJECTIVES: Resistance to pyrimethamine in Plasmodium falciparum is conferred by mutations in the gene encoding dihydrofolate reductase (DHFR). It is known that DHFR double mutants have evolved independently in multiple geographic areas, whereas the triple mutant prevalent in Africa appears to have originated in south-east Asia. In this study, we investigated whether other triple mutants may have evolved independently in Africa. METHODS: We determined the DHFR genotypes and haplotypes of five microsatellite loci flanking the DHFR locus between 4.49 kb upstream and 1.48 kb downstream of 159 isolates collected from three African countries (Republic of Congo, Ghana and Kenya). RESULTS: The CIRNI type of DHFR triple mutant (with mutations underlined at amino acid positions 51, 59 and 108) was predominant in the Republic of Congo (82%) and Ghana (81%) and was the second most prevalent in Kenya (27%), where the CICNI type of DHFR double mutant was dominant. Three distinct microsatellite haplotypes were identified in the DHFR triple mutant. One haplotype was identical to that originating in south-east Asia. The other two haplotypes occurred in Ghana and Kenya, which were unique, previously undescribed and identical to those of the two DHFR double mutants found in the same locations. CONCLUSIONS: This study presents strong evidence for the unique, multiple independent evolution of pyrimethamine resistance in Africa. Indigenous evolution of the triple mutant from the double mutant appears to have occurred in a step-wise manner in Kenya and Ghana or in nearby countries in east and west Africa.

Effect of expanded insecticide-treated bednet coverage on child survival in rural Kenya: a longitudinal study.

BACKGROUND: The potential of insecticide-treated bednets (ITNs) to contribute to child survival has been well documented in randomised controlled trials. ITN coverage has increased rapidly in Kenya from 7% in 2004 to 67% in 2006. We aimed to assess the extent to which this investment has led to improvements in child survival. METHODS: A dynamic cohort of about 3500 children aged 1-59 months were enumerated three times at yearly intervals in 72 rural clusters located in four districts of Kenya. The effect of ITN use on mortality was assessed with Poisson regression to take account of potential effect-modifying and confounding covariates. FINDINGS: 100 children died over 2 years. Overall mortality rates were much the same in the first and second years of the study (14.5 per 1000 person-years in the first year and 15.4 per 1000 person-years in the second). After adjustment for age, time period, and a number of other possible confounding variables, ITN use was associated with a 44% reduction in mortality (mortality rate ratio 0.56, 95% CI 0.33-0.96; p=0.04). This level of protection corresponds to about seven deaths averted for every 1000 ITNs distributed. INTERPRETATION: A combined approach of social marketing followed by mass free distribution of ITNs translated into child survival effects that are comparable with those seen in previous randomised controlled trials.

A randomized, open-label, comparative efficacy trial of artemether-lumefantrine suspension versus artemether-lumefantrine tablets for treatment of uncomplicated Plasmodium falciparum malaria in children in western Kenya.

BACKGROUND: Artemether/lumefantrine (AL) has been adopted as the treatment of choice for uncomplicated malaria in Kenya and other countries in the region. Six-dose artemether/lumefantrine tablets are highly effective and safe for the treatment of infants and children weighing between five and 25 kg with uncomplicated Plasmodium falciparum malaria. However, oral paediatric formulations are urgently needed, as the tablets are difficult to administer to young children, who cannot swallow whole tablets or tolerate the bitter taste of the crushed tablets. METHODS: A randomized, controlled, open-label trial was conducted comparing day 28 PCR corrected cure-rates in 245 children aged 6-59 months, treated over three days with either six-dose of artemether/lumefantrine tablets (Coartem) or three-dose of artemether/lumefantrine suspension (Co-artesiane) for uncomplicated falciparum malaria in western Kenya. The children were followed-up with clinical, parasitological and haematological evaluations over 28 days. RESULTS: Ninety three percent (124/133) and 90% (121/134) children in the AL tablets and AL suspension arms respectively completed followed up. A per protocol analysis revealed a PCR-corrected parasitological cure rate of 96.0% at Day 28 in the AL tablets group and 93.4% in the AL suspension group, p = 0.40. Both drugs effectively cleared gametocytes and were well tolerated, with no difference in the overall incidence of adverse events. CONCLUSION: The once daily three-dose of artemether-lumefantrine suspension (Co-artesiane(R)) was not superior to six-dose artemether-lumefantrine tablets (Coartem) for the treatment of uncomplicated malaria in children below five years of age in western Kenya.

Increasing coverage and decreasing inequity in insecticide-treated bed net use among rural Kenyan children.

BACKGROUND: Inexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs). In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups. METHODS AND FINDINGS: We undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0-4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni) annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004), the introduction of heavily subsidized nets through clinics (2005), and the introduction of free mass distributed ITNs (2006). The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281); 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131), and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000). The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of the least poor, and the commercial social marketing favoured the least poor. CONCLUSIONS: Rapid scaling up of ITN coverage among Africa's poorest rural children can be achieved through mass distribution campaigns. These efforts must form an important adjunct to regular, routine access to ITNs through clinics, and each complimentary approach should aim to make this intervention free to clients to ensure equitable access among those least able to afford even the cost of a heavily subsidized net.

In-hospital morbidity and mortality due to severe malarial anemia in western Kenya.

Severe malarial anemia (SMA) is a leading cause of pediatric morbidity, hospitalization, and mortality in sub-Saharan Africa, and yet its contribution to malaria-specific mortality is not well documented. We retrospectively reviewed the clinical records of 1,116 children < 5 years of age admitted to Siaya district hospital, western Kenya, to assess the contribution of SMA to overall in-hospital mortality. Of 1,116 admissions, 86% were under 3 years, 83% had malaria parasitemia, 86% were anemic, 21% were severely anemic, and 20% were transfused. Severe anemia was associated with parasitemia in 85% of the admissions and contributed to 53% of malaria-related deaths. Overall, 83 (7.5%) children died; 66% of those deaths were malaria-related, 12% had severe anemia, and 89% were under 3 years. Transfusion did not lower mortality rates. In areas of high malaria transmission, children below 3 years are a high-risk group for malaria, anemia, blood transfusion, and mortality.

The challenges of changing national malaria drug policy to artemisinin-based combinations in Kenya.

BACKGROUND: Sulphadoxine/sulphalene-pyrimethamine (SP) was adopted in Kenya as first line therapeutic for uncomplicated malaria in 1998. By the second half of 2003, there was convincing evidence that SP was failing and had to be replaced. Despite several descriptive investigations of policy change and implementation when countries moved from chloroquine to SP, the different constraints of moving to artemisinin-based combination therapy (ACT) in Africa are less well documented. METHODS: A narrative description of the process of anti-malarial drug policy change, financing and implementation in Kenya is assembled from discussions with stakeholders, reports, newspaper articles, minutes of meetings and email correspondence between actors in the policy change process. The narrative has been structured to capture the timing of events, the difficulties and hurdles faced and the resolutions reached to the final implementation of a new treatment policy. RESULTS: Following a recognition that SP was failing there was a rapid technical appraisal of available data and replacement options resulting in a decision to adopt artemether-lumefantrine (AL) as the recommended first-line therapy in Kenya, announced in April 2004. Funding requirements were approved by the Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) and over 60 million US$ were agreed in principle in July 2004 to procure AL and implement the policy change. AL arrived in Kenya in May 2006, distribution to health facilities began in July 2006 coincidental with cascade in-service training in the revised national guidelines. Both training and drug distribution were almost complete by the end of 2006. The article examines why it took over 32 months from announcing a drug policy change to completing early implementation. Reasons included: lack of clarity on sustainable financing of an expensive therapeutic for a common disease, a delay in release of funding, a lack of comparative efficacy data between AL and amodiaquine-based alternatives, a poor dialogue with pharmaceutical companies with a national interest in antimalarial drug supply versus the single sourcing of AL and complex drug ordering, tendering and procurement procedures. CONCLUSION: Decisions to abandon failing monotherapy in favour of ACT for the treatment of malaria can be achieved relatively quickly. Future policy changes in Africa should be carefully prepared for a myriad of financial, political and legislative issues that might limit the rapid translation of drug policy change into action.

Anemia and malaria at different altitudes in the western highlands of Kenya.

Malaria associated severe anemia in children is the most important complication of Plasmodium falciparum infection in sub-Saharan Africa. To evaluate anemia and malaria in an area with recurrent malaria epidemics in the western highlands of Kenya, we conducted cross-sectional surveys in four "lowland" (1440-1660 m) and two "highland" (1960 and 2040 m) villages in 2002. Among 1314 subjects randomly selected from all age groups, the overall prevalence of anemia (hemoglobin, Hb < 11 g/dl) was 14% and P. falciparum infection 17%. In children < or =5 years, anemia prevalence ranged from 57% at 1440 m to 11% at 2040 m and correlated with altitude (r = -0.88, P < 0.05). Similarly, P. falciparum prevalence ranged from 31 to 0% and correlated with altitude (r = -0.93, P < 0.01). Malnutrition defined by a body mass index <15th percentile characterized 39% of the population and the hookworm prevalence was 3.9%. In the lowland villages, anemia was most common in children < or =5 years of age (34%) followed by women of childbearing age (16%). A similar pattern was also observed in the highland villages. In these vulnerable populations, hemoglobin concentration was significantly associated with malaria infection, but not with malnutrition or hookworm infestation and comparisons of anemia prevalence between highland and lowland villages revealed that two-thirds of anemia could be attributed to malaria infection. The prevalence of severe anemia (Hb < 8 g/dl) was 1.5%; of these, 90% resided in lowland villages, 70% were under-fives, while 20% were women of childbearing age. In severely anemic subjects, the Hb concentration decreased further with malnutrition (P < 0.05). Anemia was more prevalent in the lowland villages characterized by high prevalence of P. falciparum infection. We conclude that malaria may also be the main cause of anemia in the highland fringe areas of sub-Saharan Africa. Measures that reduce the prevalence of malaria will consequently reduce anemia in both, young children and adult women and the need for blood transfusions associated with the risk of HIV-transmission.

Evaluating different dimensions of programme effectiveness for private medicine retailer malaria control interventions in Kenya.

BACKGROUND: Private medicine retailers (PMRs) are key partners in the home management of fevers in many settings. Current evidence on effectiveness for PMR interventions at scale is limited. This study presents evaluation findings of two different programs implemented at moderate scale targeting PMRs for malaria control in the Kisii and Kwale districts of Kenya. Key components of this evaluation were measurement of program performance, including coverage, PMR knowledge, practices, and utilization based on spatial analysis. METHODOLOGY/PRINCIPAL FINDINGS: The study utilized mixed quantitative methods including retail audits and surrogate client surveys based on post-intervention cross-sectional surveys in intervention and control areas and mapping of intervention outlets. There was a large and significant impact on PMR knowledge and practices of the program in Kisii, with 60.5% of trained PMRs selling amodiaquine medicines in adequate doses compared to 2.8% of untrained ones (OR; 53.5: 95% CI 6.7, 428.3), a program coverage of 69.7% targeted outlets, and a potential utilization of about 30,000 children under five. The evaluation in Kwale also indicates a significant impact with 18.8% and 2.3% intervention and control PMRs selling amodiaquine with correct advice, respectively (OR; 9.4: 95% CI 1.1, 83.7), a program coverage of 25.3% targeted outlets, and a potential utilization of about 48,000 children under five. A provisional benchmark of 7.5 km was a reasonable threshold distance for households to access PMR services. CONCLUSIONS/SIGNIFICANCE: This evaluation show that PMR interventions operationalized in the district level settings are likely to impact PMR knowledge and practices and lead to increased coverage of appropriate treatment to target populations. There is value of evaluating different dimensions of public health programs, including quality, spatial access, and implementation practice. This approach strengthens the potential contribution of pragmatic study designs to evaluating public health programs in the real world.

Performance of malaria rapid diagnostic tests as part of routine malaria case management in Kenya.

Data on malaria rapid diagnostic test (RDT) performance under routine program conditions are limited. We assessed the attributes of RDTs performed by study and health facility (HF) staffs as part of routine malaria case management of patients > or = 5 years of age in Kenya. Expert microscopy was used as our gold standard. A total of 1,827 patients were enrolled; 191 (11.6%) were parasitemic by expert microscopy. Sensitivity and specificity of RDTs performed by study staff were 86.6% (95% confidence interval [CI]: 79.8-93.5%) and 95.4% (95% CI: 93.9-96.9%), respectively. Among tests performed by HF staff, RDTs were 91.7% (95% CI: 80.8-100.0%) sensitive and 96.7% (95% CI: 92.8-100.0%) specific, whereas microscopy was 52.5% (95% CI: 33.2-71.9%) sensitive and 77.0% (95% CI: 67.9-86.2%) specific. Our findings suggest that RDTs perform better than microscopy under routine conditions. Further efforts are needed to maintain this high RDT performance over time.

Effect of malaria rapid diagnostic tests on the management of uncomplicated malaria with artemether-lumefantrine in Kenya: a cluster randomized trial.

Shortly after Kenya introduced artemether-lumefantrine (AL) for first-line treatment of uncomplicated malaria, we conducted a pre-post cluster randomized controlled trial to assess the effect of providing malaria rapid diagnostic tests (RDTs) on recommended treatment (patients with malaria prescribed AL) and overtreatment (patients without malaria prescribed AL) in outpatients >/= 5 years old. Sixty health facilities were randomized to receive either RDTs plus training, guidelines, and supervision (TGS) or TGS alone. Of 1,540 patients included in the analysis, 7% had uncomplicated malaria. The provision of RDTs coupled with TGS emphasizing AL use only after laboratory confirmation of malaria reduced recommended treatment by 63%-points (P = 0.04), because diagnostic test use did not change (-2%-points), but health workers significantly reduced presumptive treatment with AL for patients with a clinical diagnosis of malaria who did not undergo testing (-36%-points; P = 0.03). Health workers generally adhered to RDT results when prescribing AL: 88% of RDT-positive and 9% of RDT-negative patients were treated with AL, respectively. Overtreatment was low in both arms and was not significantly reduced by the provision of RDTs (-12%-points, P = 0.30). RDTs could potentially improve malaria case management, but we urgently need to develop more effective strategies for implementing guidelines before large scale implementation.