Browsing by Author "Gosling, Roly"

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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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    District‑level approach for tailoring and targeting interventions: A new path for malaria control and elimination
    (2020) Gosling, Roly; Chimumbwa, John; Uusiku, Petrina; Rossi, Sara; Ntuku, Henry; Harvard, Kelly; White, Chris; Tatarsky, Allison; Chandramohan, Daniel; Chen, Ingrid
    Despite huge investments and implementation of effective interventions for malaria, progress has stalled, with transmission being increasingly localized among difficult-to-reach populations and outdoor-biting vectors. Targeting difficult pockets of transmission will require the development of tailored and targeted approaches suited to local context, drawing from insights close to the frontlines. Districts are best placed to develop tailored, locally appropriate approaches. We propose a reorganization of how malaria services are delivered. Firstly, enabling district health officers to serve as conduits between technical experts in national malaria control programmes and local community leaders with knowledge specific to local, at-risk populations; secondly, empowering district health teams to make malaria control decisions. This is a radical shift that requires the national programme to cede some control. Shifting towards a district or provincial level approach will necessitate deliberate planning, and repeated, careful assessment, starting with piloting and learning through experience. Donors will need to alter current practice, allowing for flexible funding to be controlled at sub-national levels, and to mix finances between case management, vector control and surveillance, monitoring and evaluation. System-wide changes proposed are challenging but may be necessary to overcome stalled progress in malaria control and elimination and introduce targeted interventions tailored to the needs of diverse malaria affected populations.
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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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    Malaria risk factors in northern Namibia: The importance of occupation rage and mobility in characterizing high-risk population
    (PLOS ONE, 2021) Smith, Jennifer L.; Mumbengegwi, Davis R.; Haindongo, Erastus H.; Cueto, Carmen; Roberts, Kathryn W.; Gosling, Roly; Uusiku, Petrina; Kleinschmidt, Immo; Bennett, Adam; Sturrock, Hugh J.
    In areas of low and unstable transmission, malaria cases occur in populations with lower access to malaria services and interventions, and in groups with specific malaria risk exposures often away from the household. In support of the Namibian National Vector Borne Disease Program’s drive to better target interventions based upon risk, we implemented a health facility-based case control study aimed to identify risk factors for symptomatic malaria in Zambezi Region, northern Namibia. A total of 770 febrile individuals reporting to 6 health facilities and testing positive by rapid diagnostic test (RDT) between February 2015 and April 2016 were recruited as cases; 641 febrile individuals testing negative by RDT at the same health facilities through June 2016 were recruited as controls. Data on socio-demographics, housing construction, overnight travel, use of malaria prevention and outdoor behaviors at night were collected through interview and recorded on a tablet-based questionnaire. Remotely-sensed environmental data were extracted for geo-located village residence locations. Multivariable logistic regression was conducted to identify risk factors and latent class analyses (LCA) used to identify and characterize high-risk subgroups. The majority of participants (87% of cases and 69% of controls) were recruited during the 2016 transmission season, an outbreak year in Southern Africa. After adjustment, cases were more likely to be cattle herders (Adjusted Odds Ratio (aOR): 4.46 95%CI 1.05–18.96), members of the police or other security personnel (aOR: 4.60 95%CI: 1.16–18.16), and pensioners/unemployed persons (aOR: 2.25 95%CI 1.24–4.08), compared to agricultural workers (most common category). Children (aOR 2.28 95%CI 1.13–4.59) and self-identified students were at higher risk of malaria (aOR: 4.32 95%CI 2.31–8.10). Other actionable risk factors for malaria included housing and behavioral characteristics, including traditional home construction and sleeping in an open structure (versus modern structure: aOR: 2.0195%CI 1.45–2.79 and aOR: 4.76 95%CI: 2.14–10.57); cross border travel in the prior 30days (aOR: 10.55 95%CI 2.94–37.84); and outdoor agricultural work at night (aOR: 2.09 95%CI 1.12–3.87). Malaria preventive activities were all protective and included personal use of an insecticide treated net (ITN) (aOR: 0.61 95%CI 0.42–0.87), adequate household ITN coverage (aOR: 0.63 95%CI 0.42–0.94), and household indoor residual spraying (IRS) in the past year (versus never sprayed: (aOR: 0.63 95%CI 0.44–0.90). A number of environmental factors were associated with increased risk of malaria, including lower temperatures, higher rainfall and increased vegetation for the 30 days prior to diagnosis and residing more than 5 minutes from a health facility. LCA identified six classes of cases, with class membership strongly correlated with occupation, age and select behavioral risk factors. Use of ITNs and IRS coverage was similarly low across classes. For malaria elimination these high-risk groups will need targeted and tailored intervention strategies, for example, by implementing alternative delivery methods of interventions through schools and worksites, as well as the use of specific interventions that address outdoor transmission.
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    Malaria risk in young male travelers but local transmission persists: A case–control study in low transmission Namibia
    (2017) Smith, Jennifer L.; Auala, Joyce R.; Haindongo, Erastus H.; Uusiku, Petrina; Gosling, Roly; Kleinschmidt, Immo; Mumbengegwi, Davis R.; Sturrock, Hugh J.
    Background: A key component of malaria elimination campaigns is the identification and targeting of high risk populations. To characterize high risk populations in north central Namibia, a prospective health facility-based case–control study was conducted from December 2012–July 2014. Cases (n = 107) were all patients presenting to any of the 46 health clinics located in the study districts with a confirmed Plasmodium infection by multi-species rapid diagnostic test (RDT). Population controls (n = 679) for each district were RDT negative individuals residing within a household that was randomly selected from a census listing using a two-stage sampling procedure. Demographic, travel, socio-economic, behavioural, climate and vegetation data were also collected. Spatial patterns of malaria risk were analysed. Multivariate logistic regression was used to identify risk factors for malaria. Results: Malaria risk was observed to cluster along the border with Angola, and travel patterns among cases were comparatively restricted to northern Namibia and Angola. Travel to Angola was associated with excessive risk of malaria in males (OR 43.58 95% CI 2.12–896), but there was no corresponding risk associated with travel by females. This is the first study to reveal that gender can modify the effect of travel on risk of malaria. Amongst non-travellers, male gender was also associated with a higher risk of malaria compared with females (OR 1.95 95% CI 1.25–3.04). Other strong risk factors were sleeping away from the household the previous night, lower socioeconomic status, living in an area with moderate vegetation around their house, experiencing moderate rainfall in the month prior to diagnosis and living <15 km from the Angolan border. Conclusions: These findings highlight the critical need to target malaria interventions to young male travellers, who have a disproportionate risk of malaria in northern Namibia, to coordinate cross-border regional malaria prevention initiatives and to scale up coverage of prevention measures such as indoor residual spraying and long-lasting insecticide nets in high risk areas if malaria elimination is to be realized.
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    Spatial clustering of patent and sub-patent malaria infections in northern Namibia: Implications for surveillance and response strategies for elimination
    (2017) Smith, Jennifer L.; Auala, Joyce R.; Tambo, Munyaradzi; Haindongo, Erastus H.; Katokele, Stark; Uusiku, Petrina; Gosling, Roly; Kleinschmidt, Immo; Mumbengegwi, Davis R.; Sturrock, Hugh J.
    Reactive case detection (RACD) around passively detected malaria cases is a strategy to identify and treat hotspots of malaria transmission. This study investigated the unproven assumption on which this approach is based, that in low transmission settings, infections cluster over small scales.
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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.