Browsing by Author "Ngara, Mtakai."

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    Evaluation of the protective efficacy of Olyset®Plus ceiling net on reducing malaria prevalence in children in Lake Victoria Basin, Kenya: study protocol for a cluster-randomized controlled trial
    (Springer Nature, 2023-05-25) Kagaya, Wataru.; Chan, Chim W.; Kongere, James.; Kanoi, Bernard N.; Ngara, Mtakai.; Omondi, Protus.; Osborne, Ashley.; Barbieri, Laura.; Kc, Achyut.; Minakawa, Noboru.; Gitaka, Jesse.; Kaneko, Akira.
    Background In the Lake Victoria Basin of western Kenya, malaria remains highly endemic despite high coverage of interventions such as insecticide-impregnated long-lasting insecticidal nets (LLIN). The malaria-protective effect of LLINs is hampered by insecticide resistance in Anopheles vectors and its repurposing by the community. Ceiling nets and LLIN with synergist piperonyl butoxide (PBO-LLIN) are novel tools that can overcome the problems of behavioral variation of net use and metabolic resistance to insecticide, respectively. The two have been shown to reduce malaria prevalence when used independently. Integration of these two tools (i.e., ceiling nets made with PBO-LLIN or Olyset®Plus ceiling nets) appears promising in further reducing the malaria burden. Methods A cluster-randomized controlled trial is designed to assess the effect of Olyset®Plus ceiling nets on reducing malaria prevalence in children on Mfangano Island in Homa Bay County, where malaria transmission is moderate. Olyset®Plus ceiling nets will be installed in 1315 residential structures. Malaria parasitological, entomological, and serological indicators will be measured for 12 months to compare the effectiveness of this new intervention against conventional LLIN in the control arm. Discussion Wider adoption of Olyset®Plus ceiling nets to complement existing interventions may benefit other malaria-endemic counties and be incorporated as part of Kenya’s national malaria elimination strategy.
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    Non-Random Distribution of Plasmodium Species Infections and Associated Clinical Features in Children in The Lake Victoria Region, Kenya, 2012-2018
    (Research square, 2024-06-10) Omondi, Protus.; Musyoka, Brian.; Okai, Takatsugu.; Kongere, James.; Kagaya, Wataru.; Chan, Chim.; Ngara, Mtakai.; Kanoi, Bernard.; Kido, Yasutoshi.; Gitaka, Jesse.; Kaneko, Akira.
    Background While Plasmodium falciparum (Pf) stands out as the most lethal malaria parasite species in humans, the impact of other species should not be dismissed. Moreover, there is a notable lack of understanding of mixed-species infections and their clinical implications. Methods We conducted eight school-based cross-sectional malariometric surveys in the Lake Victoria region of western Kenya between 2012 and 2018. Plasmodium infection was determined by microscopy and nested polymerase chain reaction (PCR). The multiple-kind lottery (MKL) model calculated the expected distribution of Plasmodium infections in the population and compared it to observed values using a chi-squared test (χ2). Results The Plasmodium prevalence by PCR was 51.1% (4969/9724). Among all infections, Pf, P. malariae (Pm), and P. ovale (Po) mono-infections were 58.6%, 3.0%, and 1.7%, respectively. Pf/Pm, Pf/Po, Pm/Po, and Pf/Pm/Po co-infections were 23.5%, 4.3%, 0.1%, and 8.6%, respectively. MKL modelling revealed non-random distributions with frequencies of Pf/Pm and Pf/Pm/Po co-infections higher than expected (χ2 = 3385.60, p < 0.001). Pf co-infections with Pm and Po were associated with a decreased risk of fever (aOR 0.64, 95% CI 0.46–0.83; p = 0.01) and increased risks of splenomegaly (aOR 12.79, 95% CI 9.69–16.9; p < 0.001) and anaemia (aOR 2.57, 95% CI 2.09–3.15; p < 0.001), compared to single-species infections. Conclusion This study sheds light on the potential interaction between Pf and Pm and/or Po. Given the clinical significance of mixed-species infections, improved diagnostics, and case management of Pm and Po are urgently needed.
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    Unraveling the “indirect effects” of interventions against malaria endemicity: A systematic scoping review
    (Cold spring harbor laboratory, 2024-05-08) Kagaya, Wataru.; Chan, Chim W.; Kanamori, Mariko.; Mbugua, Samuel M.; Rotich, Alex K.; Kanoi, Bernard N.; Ngara, Mtakai.; Gitaka, Jesse.; Kaneko, Akira.
    There is an urgent need to maximize the effectiveness of existing malaria interventions and optimize the deployment of novel countermeasures. When assessing the effects of interventions against malaria, it is imperative to consider the interdependence of people and the resulting indirect effects, without which the impact on health outcomes and their cost-effectiveness may be miscalculated. Here, we conducted a scoping review of existing literature on the indirect effects of malaria interventions. We observed a recent increase in both the number of reports and the variety of terms used to denote indirect effects. We further classified eight categories of comparative analysis to identify the indirect effects, proposed common terms for the indirect effects, and highlighted the potential benefits of mathematical models in estimating indirect effects. Improving the study design and reporting the indirect effects of malaria interventions will lead to better informed decisions by policymakers.