Browsing by Author "Hsiang, M."

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    Assessing malaria risk at night-time venues in a low-transmission setting: A time-location sampling study in Zambezi, Namibia
    (2011) Jacobson, Jerry O.; Smith, Jennifer L.; Cueto, Carmen; Chisenga, Mukosha; Roberts, Kathryn W.; Hsiang, M.; Gosling, Roly; Mumbengegwi, Davis R.; Bennett, Adam
    Background:Identifying efficient and effective strategies to reach and monitor populations at greatest risk of malaria in low-transmission settings is a key challenge for malaria elimination. In Namibia’s Zambezi Region, transmis-sion is ongoing yet its drivers remain poorly understood. A growing literature suggests that night-time social activities may lead to malaria exposure that is beyond the reach of conventional preventive interventions, such as insecticide treated bed nets and indoor residual spraying.Methods:Formative research was conducted with community members in March, 2015 in the catchment areas of six randomly selected health facilities in the western Zambezi Region to identify night-time locations where large numbers of individuals regularly congregate. Using time-location sampling, a survey was conducted between March and May, 2015 at community-identified venues (bars and evening church services) to develop representative esti-mates of the prevalence of parasite infection and risk factors among venue-goers.Results:When compared to a contemporaneous household survey of the general population aged 15 and older (N =1160), venue-goers (N =480) were more likely to have spent the night away from their home recently (17.3% vs. 8.9%, P =0.008), report recent fever (65.2% vs. 36.9%, P < 0.001), and were less likely to have sought care for fever (37.9% vs. 52.1%, P =0.011). Venue-goers had higher, but not significantly different, rates of malaria infection (4.7% vs. 2.8%, P =0.740). Risk factors for malaria infection among venue-goers could not be determined due to the small number of infections identified, however self-reported fever was positively associated with outdoor livelihood activi-ties (adjusted odds ratio [AOR] =1.9, 95% CI 1.0–3.3), not wearing protective measures at the time of the survey (AOR =6.8, 9% CI 1.4–33.6) and having been bothered by mosquitos at the venue (AOR =2.7, 95% CI 1.5–4).Conclusions:Prevention measures and continued surveillance at night-time venues may be a useful complement to existing malaria elimination efforts.
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    Is there a correlation between malaria incidence and IRS coverage in western Zambezi region, Namibia?
    (2018) Mumbengegwi, Davis R.; Sturrock, Hugh J.; Hsiang, M.; Roberts, Kathryn W.; Kleinschmidt, Immo; Nghipumbwa, M.H.; Uusiku, Petrina; Smith, Jennifer L.; Bennet, A.; Kizito, W.; Takarinda, K.C.; Ade, S.; Gosling, Roly
    Setting: A comparison of routine Namibia National Malaria Programme data (reported) vs. household survey data (administrative) on indoor residual spraying (IRS) in western Zambezi region, Namibia, for the 2014–2015 malaria season. Objectives: To determine 1) IRS coverage (administrative and reported), 2) its effect on malaria incidence, and 3) reasons for non-uptake of IRS in western Zambezi region, Namibia, for the 2014–2015 malaria season. Design: This was a descriptive study. Results: IRS coverage in western Zambezi region was low, ranging from 42.3% to 52.2% for administrative coverage vs. 45.9–66.7% for reported coverage. There was no significant correlation between IRS coverage and malaria incidence for this region (r = –0.45, P = 0.22). The main reasons for households not being sprayed were that residents were not at home during spraying times or that spray operators did not visit the households. Conclusions: IRS coverage in western Zambezi region, Namibia, was low during the 2014–2015 malaria season because of poor community engagement and awareness of times for spray operations within communities. Higher IRS coverage could be achieved through improved community engagement. Better targeting of the highest risk areas by the use of malaria surveillance will be required to mitigate malaria transmission.
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    Study protocol for a cluster randomised controlled factorial design trial to assess the effectiveness and feasibility of reactive focal mass drug administration and vector control to reduce malaria transmission in the low endemic setting of Namibia
    (2017) Medzihradsky, Oliver F.; Kleinschmidt, Immo; Mumbengegwi, Davis R.; Roberts, Kathryn W.; McCreesh, Patrick; Dufour, Mi-Suk Kang; Uusiku, Petrina; Katokele, Stark; Bennet, A.; Smith, Jennifer L.; Sturrock, Hugh J.; Prach, Lisa M.; Nkutu, Henry; Tambo, Munyaradzi; Didier, Bradley; Greenhouse, Bryan; Gani, Zaahira; Aerts, Ann; Gosling, Roly; Hsiang, M.
    Introduction To interrupt malaria transmission, strategies must target the parasite reservoir in both humans and mosquitos. Testing of community members linked to an index case, termed reactive case detection (RACD), is commonly implemented in low transmission areas, though its impact may be limited by the sensitivity of current diagnostics. Indoor residual spraying (IRS) before malaria season is a cornerstone of vector control efforts. Despite their implementation in Namibia, a country approaching elimination, these methods have been met with recent plateaus in transmission reduction. This study evaluates the effectiveness and feasibility of two new targeted strategies, reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) in Namibia. Methods and analysis This is an open-label cluster randomised controlled trial with 2×2 factorial design. The interventions include: rfMDA (presumptive treatment with artemether-lumefantrine (AL)) versus RACD (rapid diagnostic testing and treatment using AL) and RAVC (IRS with Acellic 300CS) versus no RAVC. Factorial design also enables comparison of the combined rfMDA+RAVC intervention to RACD. Participants living in 56 enumeration areas will be randomised to one of four arms: rfMDA, rfMDA+RAVC, RACD or RACD+RAVC. These interventions, triggered by index cases detected at health facilities, will be targeted to individuals residing within 500 m of an index. The primary outcome is cumulative incidence of locally acquired malaria detected at health facilities over 1 year. Secondary outcomes include seroprevalence, infection prevalence, intervention coverage, safety, acceptability, adherence, cost and costeffectiveness.