Yield-phenology relation is a critical issue affecting rainfed maize field productivity in semiarid east African Plateau (EAP). We first introduced Chinese ridge-furrow mulching (RFM) system to EAP, ...using three maize cultivars with early-, mid- and late-maturing traits as test materials. A two-year field experiment was conducted in a semiarid farm of Kenya from 2012 to 2013. Three treatments were designed: alternative ridge and furrow with transparent plastic mulching (FT), with black plastic mulching (FB) and without mulching (CK). We found that FT and FB significantly increased soil moisture and accelerated crop maturity across two growing seasons. Leaf area and shoot biomass were increased by 30.2% and 67.5% in FT, 35.2% and 73.5% in FB, respectively, compared with CK. Grain yield, water use efficiency and economic output were increased by 55.6%, 57.5% and 26.7% in FT, and 50.8%, 53.3% and 19.8% in FB, respectively. Optimal yield and economic benefit were observed in late-maturing cultivar due to increased topsoil temperature in FT in 2012 (cool), and in early-maturing cultivar owing to cooling effect in FB in 2013 (warm). Our study suggested RFM system, combined with crop phenology selection, be a promising strategy to boost maize productivity and profitability in semiarid EAP.
Malaria transmission is highly heterogeneous, generating malaria hotspots that can fuel malaria transmission across a wider area. Targeting hotspots may represent an efficacious strategy for reducing ...malaria transmission. We determined the impact of interventions targeted to serologically defined malaria hotspots on malaria transmission both inside hotspots and in surrounding communities.
Twenty-seven serologically defined malaria hotspots were detected in a survey conducted from 24 June to 31 July 2011 that included 17,503 individuals from 3,213 compounds in a 100-km2 area in Rachuonyo South District, Kenya. In a cluster-randomized trial from 22 March to 15 April 2012, we randomly allocated five clusters to hotspot-targeted interventions with larviciding, distribution of long-lasting insecticide-treated nets, indoor residual spraying, and focal mass drug administration (2,082 individuals in 432 compounds); five control clusters received malaria control following Kenyan national policy (2,468 individuals in 512 compounds). Our primary outcome measure was parasite prevalence in evaluation zones up to 500 m outside hotspots, determined by nested PCR (nPCR) at baseline and 8 wk (16 June-6 July 2012) and 16 wk (21 August-10 September 2012) post-intervention by technicians blinded to the intervention arm. Secondary outcome measures were parasite prevalence inside hotpots, parasite prevalence in the evaluation zone as a function of distance from the hotspot boundary, Anopheles mosquito density, mosquito breeding site productivity, malaria incidence by passive case detection, and the safety and acceptability of the interventions. Intervention coverage exceeded 87% for all interventions. Hotspot-targeted interventions did not result in a change in nPCR parasite prevalence outside hotspot boundaries (p ≥ 0.187). We observed an average reduction in nPCR parasite prevalence of 10.2% (95% CI -1.3 to 21.7%) inside hotspots 8 wk post-intervention that was statistically significant after adjustment for covariates (p = 0.024), but not 16 wk post-intervention (p = 0.265). We observed no statistically significant trend in the effect of the intervention on nPCR parasite prevalence in the evaluation zone in relation to distance from the hotspot boundary 8 wk (p = 0.27) or 16 wk post-intervention (p = 0.75). Thirty-six patients with clinical malaria confirmed by rapid diagnostic test could be located to intervention or control clusters, with no apparent difference between the study arms. In intervention clusters we caught an average of 1.14 female anophelines inside hotspots and 0.47 in evaluation zones; in control clusters we caught an average of 0.90 female anophelines inside hotspots and 0.50 in evaluation zones, with no apparent difference between study arms. Our trial was not powered to detect subtle effects of hotspot-targeted interventions nor designed to detect effects of interventions over multiple transmission seasons.
Despite high coverage, the impact of interventions targeting malaria vectors and human infections on nPCR parasite prevalence was modest, transient, and restricted to the targeted hotspot areas. Our findings suggest that transmission may not primarily occur from hotspots to the surrounding areas and that areas with highly heterogeneous but widespread malaria transmission may currently benefit most from an untargeted community-wide approach. Hotspot-targeted approaches may have more validity in settings where human settlement is more nuclear.
ClinicalTrials.gov NCT01575613.
In this randomized, placebo-controlled trial in children younger than 5 years of age with severe anemia in an area in which malaria is endemic, dihydroartemisinin–piperaquine administered after ...hospital discharge resulted in a lower incidence of readmission or death in the 3 months after discharge than placebo.
A recent meta-analysis of 14 clinical trials indicated that daily compared with intermittent iron supplementation resulted in significantly greater hematological improvement in pregnant women. No ...such definitive beneficial effect was demonstrated in preschool children. We compared the efficacy of daily and twice weekly iron supplementation for 6 wk under supervised and unsupervised conditions in the treatment of mild and moderate anemia hemoglobin (Hb) 50-109 g/L in children aged 2-59 mo living in a malaria-endemic area of western Kenya. The study was a cluster-randomized trial using a factorial design; participants were aware of the treatment assigned. All children (n = 1049) were administered a single dose of sulfadoxine-pyrimethamine at enrollment followed by 6 wk of daily supervised iron supplementation 3-6 mg/(kg . d), twice weekly supervised iron supplementation 6-12 mg/(kg . wk), daily unsupervised iron supplementation, or twice weekly unsupervised iron supplementation. In the supervised groups, Hb concentrations at 6 and 12 wk (6 wk postsupplementation) were significantly higher in children given iron daily rather than twice weekly mean (95% CI) difference at 6-wk: 4.2 g/L (2.1, 6.4); 12-wk: 4.4 g/L (1.8, 7.0). Among the unsupervised groups, Hb concentrations were not different at 6 wk mean (95% CI) difference: 0.86 g/L (-1.4, 3.1), but significantly higher at 12 wk for those assigned daily iron mean (95% CI) difference: 3.4 g/L (0.79, 6.0), P = 0.02. In this malarious area and after initial antimalarial treatment, 6 wk of daily iron supplementation results in better hematological responses than twice weekly iron supplementation in the treatment of anemia in preschool children, regardless of whether adherence can be ensured. J. Nutr. 134:1167-1174, 2004. PUBLICATION ABSTRACT KEY WORDS: * iron * daily * anemia * children * Kenya
We performed an economic analysis of a new technology used in antenatal care (ANC) clinics, the ANC panel. Introduced in 2019-2020 in five Rwandan districts, the ANC panel screens for four infections ...hepatitis B virus (HBV), human immunodeficiency virus (HIV), malaria, and syphilis using blood from a single fingerstick. It increases the scope and sensitivity of screening over conventional testing.
We developed and applied an Excel-based economic and epidemiologic model to perform cost-effectiveness and cost-benefit analyses of this technology in Kenya, Rwanda, and Uganda. Costs include the ANC panel itself, its administration, and follow-up treatment. Effectiveness models predicted impacts on maternal and infant mortality and other outcomes. Key parameters are the baseline prevalence of each infection and the effectiveness of early treatment using observations from the Rwanda pilot, national and international literature, and expert opinion. For each parameter, we found the best estimate (with 95% confidence bound).
The ANC panel averted 92 (69-115) disability-adjusted life years (DALYs) per 1,000 pregnant women in ANC in Kenya, 54 (52-57) in Rwanda, and 258 (156-360) in Uganda. Net healthcare costs per woman ranged from $0.53 ($0.02-$4.21) in Kenya, $1.77 ($1.23-$5.60) in Rwanda, and negative $5.01 (-$6.45 to $0.48) in Uganda. Incremental cost-effectiveness ratios (ICERs) in dollars per DALY averted were $5.76 (-$3.50-$11.13) in Kenya, $32.62 ($17.54-$46.70) in Rwanda, and negative $19.40 (-$24.18 to -$15.42) in Uganda. Benefit-cost ratios were $17.48 ($15.90-$23.71) in Kenya, $6.20 ($5.91-$6.45) in Rwanda, and $25.36 ($16.88-$33.14) in Uganda. All results appear very favorable and cost-saving in Uganda.
Though subject to uncertainty, even our lowest estimates were still favorable. By combining field data and literature, the ANC model could be applied to other countries.
Background. Although children <5 years old in sub-Saharan Africa are vulnerable to both malaria and influenza, little is known about coinfection. Methods. This retrospective, cross-sectional study in ...rural western Kenya examined outpatient visits and hospitalizations associated with febrile acute respiratory illness (ARI) during a 2-year period (July 2009-June 2011) in children <5 years old. Results. Across sites, 45% (149/331) of influenza-positive patients were coinfected with malaria, whereas only 6% (149/2408) of malaria-positive patients were coinfected with influenza. Depending on age, coinfection was present in 4%–8% of outpatient visits and 1%–3% of inpatient admissions for febrile ARI. Children with influenza were less likely than those without to have malaria (risk ratio RR, 0.57–0.76 across sites and ages), and children with malaria were less likely than those without to have influenza (RR, 0.36–0.63). Among coinfected children aged 24–59 months, hospital length of stay was 2.7 and 2.8 days longer than influenza-only-infected children at the 2 sites, and 1.3 and 3.1 days longer than those with malaria only (all P < .01). Conclusions. Coinfection with malaria and influenza was uncommon but associated with longer hospitalization than single infections among children 24–59 months of age.
BACKGROUND: It has been speculated that widespread and sustained use of insecticide treated bed nets (ITNs) for over 10 years in Asembo, western Kenya, may have selected for changes in the location ...(indoor versus outdoor) and time (from late night to earlier in the evening) of biting of the predominant species of human malaria vectors (Anopheles funestus, Anopheles gambiae sensu stricto, and Anopheles arabiensis). METHODS: Mosquitoes were collected by human landing catches over a six week period in June and July, 2011, indoors and outdoors from 17 h to 07 h, in 75 villages in Asembo, western Kenya. Collections were separated by hour of the night, and mosquitoes were identified to species and tested for sporozoite infection with Plasmodium falciparum. A subset was dissected to determine parity. Human behavior (time going to bed and rising, time spent indoors and outdoors) was quantified by cross-sectional survey. Data from past studies of a similar design and in nearby settings, but conducted before the ITN scale up commenced in the early 2000s, were compared with those from the present study. RESULTS: Of 1,960 Anopheles mosquitoes collected in 2011, 1,267 (64.6%) were morphologically identified as An. funestus, 663 (33.8%) as An. gambiae sensu lato (An. gambiae s.s. and An. arabiensis combined), and 30 (1.5%) as other anophelines. Of the 663 An. gambiae s.l. collected, 385 were successfully tested by PCR among which 235 (61.0%) were identified as An. gambiae s.s. while 150 (39.0%) were identified as An. arabiensis. Compared with data collected before the scale-up of ITNs, daily entomological inoculation rates (EIRs) were consistently lower for An. gambiae s.l. (indoor EIR = 0.432 in 1985–1988, 0.458 in 1989–1990, 0.023 in 2011), and An. arabiensis specifically (indoor EIR = 0.532 in 1989–1990, 0.039 in 2009, 0.006 in 2011) but not An. funestus (indoor EIR = 0.029 in 1985–1988, 0.147 in 1989–1990, 0.010 in 2009 and 0.103 in 2011). Sporozoite rates were lowest in 2009 but rose again in 2011. Compared with data collected before the scale-up of ITNs, An. arabiensis and An. funestus were more likely to bite outdoors and/or early in the evening (p < 0.001 for all comparisons). However, when estimates of human exposure that would occur indoors (πᵢ) or while asleep (πₛ) in the absence of an ITN were generated based on human behavioral patterns, the changes were modest with >90% of exposure of non-ITN users to mosquito bites occurring while people were indoors in all years. The proportion of bites occurring among non-ITN users while they were asleep was ≥90% for all species except for An. arabiensis. For this species, 97% of bites occurred while people were asleep in 1989–1990 while in 2009 and 2011, 80% and 84% of bites occurred while people were asleep for those not using ITNs. Assuming ITNs prevent a theoretical maximum of 93.7% of bites, it was estimated that 64-77% of bites would have occurred among persons using nets while they were asleep in 1989–1990, while 20-52% of bites would have occurred among persons using nets while they were asleep in 2009 and 2011. CONCLUSIONS: This study found no evidence to support the contention that populations of Anopheles vectors of malaria in Asembo, western Kenya, are exhibiting departures from the well-known pattern of late night, indoor biting characteristic of these typically highly anthropophilic species. While outdoor, early evening transmission likely does occur in western Kenya, the majority of transmission still occurs indoors, late at night. Therefore, malaria control interventions such as ITNs that aim to reduce indoor biting by mosquitoes should continue to be prioritized.
Centromeres are specified by a centromere specific histone 3 (CENH3) protein, which exists in a complex environment, interacting with conserved proteins and rapidly evolving satellite DNA sequences. ...The interactions may become more challenging if multiple CENH3 versions are introduced into the zygote as this can affect post-zygotic mitosis and ultimately sexual reproduction. Here, we characterize
variant transcripts expressed in cultivated triploid and wild diploid progenitor bananas. We describe both splice- and allelic-Single Nucleotide Polymorphisms (SNP) variants and their effects on the predicted secondary structures of protein. Expressed
transcripts from six banana genotypes were characterized and clustered into three groups (
-1A,
-1B, and
-2) based on similarity. The
groups differed with SNPs as well as presence of indels resulting from retained and/or skipped exons. The
transcripts from different banana genotypes were spliced in either 7/6, 5/4 or 6/5 exons/introns. The 7/6 and the 5/4 exon/intron structures were found in both diploids and triploids, however, 7/6 was most predominant. The 6/5 exon/introns structure was a result of failure of the 7/6 to splice correctly. The various transcripts obtained were predicted to encode highly variable N-terminal tails and a relatively conserved C-terminal histone fold domain (HFD). The SNPs were predicted in some cases to affect the secondary structure of protein by lengthening or shorting the affected domains. Sequencing of banana
transcripts predicts SNP variations that affect amino acid sequences and alternatively spliced transcripts. Most of these changes affect the N-terminal tail of CENH3.
Identifying asymptomatic reservoirs of malaria parasites using index cases as entry points into the community is potentially a cost-effective way towards achieving malaria elimination.
Within 1 year, ...1430 confirmed malaria cases were identified in Marani hospital, western Kenya. Fifty cases were followed up, and 108 index case household members and 612 neighbours within a 100 m radius were screened. As controls, samples were collected from 510 individuals matched with index cases and located at a distance of ≥ 500 m from them. Infections were diagnosed by microscopy and PCR while simultaneously collecting malaria vectors indoor using pyrethrum spray catches.
In the index case and neighbour households, the prevalence of infection was approximately twice as high as in control households (by PCR: index cases households: 28.9%, neighbours: 25.3%, matched controls: 12.9%). In index case households, the indoor vector density (Anopheles gambiae and Anopheles funestus) was higher (0.46 female/house/night) than in neighbouring (0.31 f/h/n) and control houses (0.29 f/h/n).
Screening index case households and neighbours approximately doubles the chance to detect asymptomatic infections compared to randomly selected households. However, even if all cases were followed up, only a small proportion (˂ 10%) of the asymptomatic reservoir in the population would have been identified. Control programmes need to weigh the increased chance to find cases around index cases vs. the logistical challenges to target this subgroup within the population.
Iron supplementation has been associated with greater susceptibility to malaria and lower hematologic responses in pregnant Gambian women with sickle cell trait (HbAS) than in similar women with the ...normal (HbAA) phenotype. It is not known whether a similar interaction exists in children.
Our aim was to determine the influence of the HbAS phenotype on hematologic responses and malaria after iron supplementation in anemic (hemoglobin: 70-109 g/L) children aged 2-35 mo.
We conducted a double-blind, randomized, placebo-controlled trial (HbAS, n = 115; HbAA, n = 408) of intermittent preventive treatment with sulfadoxine pyrimethamine (IPT-SP) at 4 and 8 wk and daily supervised iron for 12 wk.
The mean difference in hemoglobin concentrations at 12 wk between children assigned iron and placebo iron, after adjustment for the effect of IPT-SP, was 9.1 g/L (95% CI: 6.4, 11.8) and 8.2 g/L (4.0, 12.4) in HbAA and HbAS children, respectively (P for interaction = 0.68). Although malaria parasitemia and clinical malaria occurred more often in HbAS children in the iron group than in those in the placebo iron group, this difference was not significant; incidence rate ratios were 1.23 (95% CI: 0.64, 2.34) and 1.41 (0.39, 5.00), respectively. The corresponding incidence rate ratios in HbAA children in the same groups were 1.07 (95% CI: 0.77, 1.48) and 0.59 (0.35, 1.01), respectively. The corresponding interactions between the effects of iron and hemoglobin phenotype were not significant.
There was no evidence for a clinically relevant modification by the hemoglobin S phenotype of the effects of iron supplementation in the treatment of mild anemia. The benefits of iron supplementation are likely to outweigh possible risks associated with malaria in children with the HbAA or HbAS phenotype.
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