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  • 1
    Online Resource
    Online Resource
    Effectiveness of screened ceilings over the current best practice in reducing malaria prevalence in western Kenya: a cluster randomized-controlled trial
    Cambridge University Press (CUP) ; 2022
    In:  Parasitology Vol. 149, No. 7 ( 2022-06), p. 944-955
    Details
    In: Parasitology, Cambridge University Press (CUP), Vol. 149, No. 7 ( 2022-06), p. 944-955
    Abstract: Increases in bed net coverage and antimalarial treatment have reduced the risk of malaria in sub-Saharan Africa. However, the pace of reduction has slowed, and new tools are needed to reverse this trend. We evaluated houses screened with insecticide-treated ceiling nets using a cluster randomized-controlled trial in western Kenya. The primary endpoints were Plasmodium falciparum PCR-positive prevalence (PCR Pf PR) of children from 7 months to 10 years old and anopheline density. Ceiling nets and bed nets were provided to 1073 houses, and 1162 houses were provided with bed nets only. The treatment and control arms each had four clusters. We conducted three epidemiological and entomological post-intervention surveys over the course of a year and a half. Each epidemiological survey targeted 150 children per cluster, and entomological surveys targeted 25 houses. When the three surveys were combined, the median PCR Pf PRs were 23% (IQR 8%) in the intervention arm and 42% (IQR 12%) in the control arm. The adjusted risk ratio (RR) was 0.53 [95% confidence interval (CI) 0.41–0.71; P = 0.029]. The median anopheline densities were 0.4 (IQR 0.4) and 2.0 (IQR 1.4), respectively. The adjusted RR was 0.41 (95% CI 0.29–0.90; P = 0.029). The present study indicates additional protection from insecticide-screened ceilings over the current best practice.
    Type of Medium: Online Resource
    ISSN: 0031-1820 , 1469-8161
    URL: Article
    DOI: 10.1017/S0031182022000415
    RVK:
    WA 15000
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1491287-9
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    A preliminary study on designing a cluster randomized control trial of two new mosquito nets to prevent malaria parasite infection
    Springer Science and Business Media LLC ; 2020
    In:  Tropical Medicine and Health Vol. 48, No. 1 ( 2020-12)
    Details
    In: Tropical Medicine and Health, Springer Science and Business Media LLC, Vol. 48, No. 1 ( 2020-12)
    Abstract: Although long-lasting insecticidal nets (LLINs) are the most effective tool for preventing malaria parasite transmission, the nets have some limitations. For example, the increase of LLIN use has induced the rapid expansion of mosquito insecticide resistance. More than two persons often share one net, which increases the infection risk. To overcome these problems, two new mosquito nets were developed, one incorporating piperonyl butoxide and another covering ceilings and open eaves. We designed a cluster randomized controlled trial (cRCT) to evaluate these nets based on the information provided in the present preliminary study. Results Nearly 75% of the anopheline population in the study area in western Kenya was Anopheles gambiae s. l. , and the remaining was Anopheles funestus s. l . More female anophelines were recorded in the western part of the study area. The number of anophelines increased with rainfall. We planned to have 80% power to detect a 50% reduction in female anophelines between the control group and each intervention group. The between-cluster coefficient of variance was 0.192. As the number of clusters was limited to 4 due to the size of the study area, the estimated cluster size was 7 spray catches with an alpha of 0.05. Of 1619 children tested, 626 (48%) were Plasmodium falciparum positive using a rapid diagnostic test (RDT). The prevalence was higher in the northwestern part of the study area. The number of children who slept under bed nets was 929 (71%). The P. falciparum RDT-positive prevalence (RDTpfPR) of net users was 45%, and that of non-users was 55% (OR 0.73; 95% CI 0.56, 0.95). Using 45% RDTpfPR of net users, we expected each intervention to reduce prevalence by 50%. The intracluster correlation coefficient was 0.053. With 80% power and an alpha of 0.05, the estimated cluster size was 116 children. Based on the distribution of children, we modified the boundaries of the clusters and established 300-m buffer zones along the boundaries to minimize a spillover effect. Conclusions The cRCT study design is feasible. As the number of clusters is limited, we will apply a two-stage procedure with the baseline data to evaluate each intervention.
    Type of Medium: Online Resource
    ISSN: 1349-4147
    URL: Article
    DOI: 10.1186/s41182-020-00276-x
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2209835-5
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  • 3
    Online Resource
    Online Resource
    Long-Lasting Insecticidal Nets Incorporating Piperonyl Butoxide Reduce the Risk of Malaria in Children in Western Kenya: A Cluster Randomized Controlled Trial
    American Society of Tropical Medicine and Hygiene ; 2021
    In:  The American Journal of Tropical Medicine and Hygiene Vol. 105, No. 2 ( 2021-08-11), p. 461-471
    Details
    In: The American Journal of Tropical Medicine and Hygiene, American Society of Tropical Medicine and Hygiene, Vol. 105, No. 2 ( 2021-08-11), p. 461-471
    Abstract: Malaria vectors have acquired an enzyme that metabolizes pyrethroids. To tackle this problem, we evaluated long-lasting insecticidal nets incorporating piperonyl butoxide (PBO-LLINs) with a community-based cluster randomized control trial in western Kenya. The primary endpoints were anopheline density and Plasmodium falciparum polymerase chain reaction (PCR)-positive prevalence (PCRpfPR) of children aged 7 months to 10 years. Four clusters were randomly selected for each of the treatment and control arms (eight clusters in total) from 12 clusters, and PBO-LLINs and standard LLINs were distributed in February 2011 to 982 and 1,028 houses for treatment and control arms, respectively. Entomological surveys targeted 20 houses in each cluster, and epidemiological surveys targeted 150 children. Cluster-level permutation tests evaluated the effectiveness using the fitted values from individual level regression models adjusted for baseline. Bootstrapping estimated 95% confidence intervals (CIs). The medians of anophelines per house were 1.4 (interquartile range [IQR]: 2.3) and 3.4 (IQR: 3.7) in the intervention and control arms after 3 months, and 0.4 (IQR: 0.2) and 1.6 (IQR: 0.5) after 10 months, respectively. The differences were –2.5 (95% CI: –6.4 to –0.6) and –1.3 (95% CI: –2.0 to –0.7), respectively. The datasets of 861 and 775 children were analyzed in two epidemiological surveys. The median PCRpfPRs were 25% (IQR: 11%) in the intervention arm and 52% (IQR: 11%) in the control arm after 5 months and 33% (IQR: 11%) and 45% (IQR: 5%) after 12 months. The PCRpfPR ratios were 0.67 (95% CI: 0.38, 0.91) and 0.74 (95% CI: 0.53, 0.90), respectively. We confirmed the superiority of PBO-LLINs.
    Type of Medium: Online Resource
    ISSN: 0002-9637 , 1476-1645
    URL: Article
    DOI: 10.4269/ajtmh.20-1069
    Language: Unknown
    Publisher: American Society of Tropical Medicine and Hygiene
    Publication Date: 2021
    detail.hit.zdb_id: 1491674-5
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