Effect of Age of ITN Owned by Households on Malaria Parasite Infection Among Children Under Five Years of Age in Angola

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Effect of Age of ITN Owned by Households on Malaria Parasite Infection Among Children Under Five Years of Age in Angola

  1. 1. Background Effect of Age of ITN Owned by Households on Malaria Parasite Infection Among Children Under Five Years of Age in Angola Methods Insecticide treated nets (ITNs) are effective for malaria control and provide protection to individuals sleeping under them and those living in households that own them. ITNs are manufactured to have a long lasting protective effect; however, the effect of the age of ITNs in households on malaria parasitemia under country-specific context and programmatic conditions is not well documented, particularly in Angola. Using 2011 malaria indicator survey (MIS) this study examined the association between the age of ITNs in households and malaria parasite prevalence among children under five years of age in Angola. ITNs that were obtained shortly before the survey may not protect children from malaria infection because the infection may have happened before the acquisition of the net. Conversely, ITNs that were obtained a longer time ago may be less protective due to wear and tear of the net, or reduction in efficacy of the insecticide. Results • Angola 2011 MIS was conducted February– May 2011. • Survey sample powered to provide estimates for urban and rural, and four malaria endemicity regions (Figure 2) . • Households interviewed were 8,030 with and 8,512 children under five year of age. • All under five children tested for malaria parasite with microcopy and rapid diagnostic test . • A logistic regression performed to assess the effect of the age of ITNs in households and malaria parasite prevalence among under five children. • Model adjusted for eight covariates: sex of child, age of child, mother’s education, household had been sprayed or not, household size, household wealth quintiles, area of residence, and malaria epidemiologic zones. • All covariates checked for collinearity and interaction. • Only one child per household included in the model to avoid cluster effects. Summary Children from households that had owned ITNs for 2-6 months before the survey were significantly less likely to have malaria parasitemia compared to those from households without ITNs (OR = 0.28, 95% CI: 0.10-0.84). ITNs that had been owned for one month or less, or for more than six months, were not protective. ITNs remain protective against malaria in Angola, however, when assessing their effects on parasite prevalence the age of the net in the household should be considered. These findings provide useful information, particularly when assessing the impact of ITN interventions on the reduction of malaria burden. Acknowledgments The authors would like to acknowledge the President’s Malaria Initiative impact evaluation team for Angola. This study was made possible by support from the U.S. Agency for International Development (USAID) under the terms of Cooperative Agreement GPO-A-00-03-00003-00. The opinions expressed are those of the authors and do not necessarily reflect the views of USAID, or the United States Government. Variables N Odds Ratio (95% CI) p value ITN ownership by age of net No ITN 1,558 1.0 ITN owned for 1 month or less 61 0.27 (0.03-2.31) 0.232 ITN owned for 2-6 months 255 0.28 (0.10-0.84) 0.023 ITN owned for 6-12 months 152 0.44 (0.12-1.60) 0.212 ITN owned for more than 12 months 83 0.29 (0.06-1.40) 0.124 Sex Male 1,032 1.0 <0.001 Female 1,077 0.95 (0.71-1.28) 0.744 Age of child 6-23 months 602 1.0 <0.001 24-59 months 1,507 1.08 (0.96-1.21) 0.207 Mother's Education None 706 1.0 Primary 1,157 0.96 (0.71-1.32) 0.822 Secondary and Higher 246 1.3 (0.44-3.85) 0.642 Household sprayed last 12 months No 1,965 1.0 Yes 144 0.5 (0.23-1.08) 0.077 Household size 3 or less members 193 1.0 <0.001 4-5 members 736 2.34 (1.25-4.36) 0.008 6-7 members 662 1.92 (1.01-3.63) 0.044 8 or more members 518 2.02 (1.04-3.92) 0.038 Wealth quintile Least poor 507 1.0 Second 618 1.98 (1.00-3.86) 0.049 Third 363 6.87 (3.57-13.20) <0.001 Fourth 280 6.57 (3.37-12.82) <0.001 Poorest 341 3.82 (1.94-7.55) <0.001 Residence Rural 1,337 1.0 Urban* 772 0.11 (0.05-0.24) <0.001 Malaria Epidemiologic Zones Hyperendemic 532 1.0 <0.001 Mesoendemic stable 564 0.47 (0.32-0.68) <0.001 Mesoendemic unstable 592 0.24 (0.16-0.37) <0.001 Luanda 421 0.67 (0.21-2.07) 0.482 N = 1937 (Model restricted to one child under-five years per household to avoid cluster effects); Pseudo R2: 0.1925; p < 0.05; CI = Confidence Interval; Figure 1: Location of Angola Data Source Statistical AnalysisFigure 2: Malaria endemicity zones Ana Franka koh1, Rebecca Winter2, Yazoume Ye1 1MEASURE Evaluation/ICF International, 2MEASURE DHS, ICF International 37 35 0 10 20 30 40 50 60 70 80 90 100 any net ITN %householdsownatleastone Figure 3: Household ownership of any nets and ITNs Source: MIS 2011 41 21 0 10 20 30 40 50 60 70 80 90 100 with children under-five without children under-five %householdsownatleastone Source: MIS 2011 Figure 4: ITN ownership in households with and without under five children Table 1: Logistic regression outputs: The effect of ITNs ownership by age of net on malaria parasitemia Figure 5: Household ownership of ITNs, by malaria epidemiologic zone 24 27 27 26 0 10 20 30 40 50 60 70 80 90 100 Hyperendemic Mesoendemic stable Mesoendemic unstable Luanda %sleptunderITNpreviousnight Figure 6: ITN use among under five children by malaria epidemiologic zone 30 36 37 35 0 10 20 30 40 50 60 70 80 90 100 Hyperendemic Mesoendemic stable Mesoendemic unstable Luanda %householdsownatleastone Source: MIS 2011 Source: MIS 2011

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