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Background: Malaria remains a major threat to some 3.2 billion persons globally. Malaria contributes heavily to the overall disease burden in Mozambique and is considered endemic. A cornerstone of Mozambique’s vector control strategy has been to strive for universal coverage of insecticide-treated nets (ITN). Methods: The study is a population-based cross-sectional survey of female heads-of-household in Zambézia Province, Mozambique conducted during August-September, 2010 and April-May, 2014. Analyses accounted for a stratified two-stage cluster sample design. Outcomes of interest included sleeping under a mosquito net during the previous night. Descriptive statistics were calculated for three oversampled districts and for the entire province. Multivariable logistic regression analysis was used to estimate factors associated with both changes over time and increased mosquito bed net usage. Results: Of the 3916 households interviewed in 2010 and 3906 households in 2014, 64.3 % were in possession of at least one mosquito bed net. A higher proportion of households in Namacurra (90 %) reported possession of a mosquito net, compared to Alto Molócuè (77 %) and Morrumbala (34 %), respectively in 2014. Of pregnant respondents, 58.6 % reported sleeping under a mosquito net the previous night in 2010 compared to 68.4 % in 2014. Fifty percent of children 0-59 months slept under a mosquito net the previous night in 2010 compared to 60 % in 2014. Factors associated with use of a mosquito net for female head-of-household respondents were higher education, understanding Portuguese, larger household size, having electricity in the household, and larger household monthly income. As travel time to a health facility increased (per 1 h), respondents had 13 % lower odds of sleeping under a mosquito net (OR 0.87; 95 % CI 0.74-1.01, p = 0.07). Pregnant women in 2014 had a 2.4 times higher odds of sleeping under a bed net if they lived in Namacurra compared to Alto Molócuè (95 % CI 0.91-6.32, p = 0.002 for district). Higher maternal education, living in Namacurra, and acquisition of mosquito bed nets were associated with a child 0-59 months reporting sleeping under the net in the previous night in 2014. Conclusions: Intensified focus on the poorest, least educated, and most distant from health services is needed to improve equity of ITN availability and usage. Additionally, while some districts have already surpassed goals in terms of coverage and utilization of ITN, renewed emphasis should be placed on bringing all geographic regions of the province closer to meeting these targets.
The design and implementation of this study are detailed elsewhere [19–22]. Briefly, survey teams completed interviews in 262 enumeration areas (EA) across Zambézia Province. A large representative sample (201 EA) was obtained from three diverse districts (Alto Molócuè, Namacurra, and Morrumbala) in order to increase the precision of survey results while minimizing costs. To further maintain a degree of generalizability across the province, a sample of households were selected for interview throughout the remaining 14 districts (Fig. 1). Map of Zambézia Province with enumeration areas surveyed. *Oversampled districts highlighted, Alto Molócuè, Morrumbala, and Namacurra Map credit: Charlotte Buehler; May 27 2015; Vanderbilt Institute for Global Health; Projection: WGS 1984 Web Mercator Auxiliary Sphere At both baseline and endline the same questionnaire was utilized. While survey responses were not collected from the same households in both surveys, the same sampling methodology was utilized with interviewers returning to the same EAs as in baseline. The Ogumaniha survey tool collects information on over 500 variables in eight dimensions and was developed by a multi-disciplinary team of researchers from Vanderbilt University and the University Eduardo Mondlane in Maputo. The survey designers borrowed many questions and scales deemed appropriate from previous national surveys in Mozambique and other international surveys such as the Demographic Health Survey (DHS) and Multiple Indicator Cluster Survey (MICS). Survey questions covered household demographics; economic status; health knowledge, attitudes and practices; access to health and malaria-related services and products; access to improved water and sanitation; nutritional intake; and others. In both surveys, fourteen mobile teams consisting of a team leader and four interviewers administered the survey face-to-face using mobile phones with an electronic questionnaire installed for data collection. Local authorities were notified prior to the arrival of the survey team. From topographic maps, the survey teams divided the EAs into four quadrants. Starting in the center of the assigned quadrant, interviewers selected a direction, then chose the first household in that direction (i.e. starting point), and approached the nearest four households for interview. Female interviewers conducted the survey with female heads-of-household, defined as the only or principal wife of the immediate family of the household. The female head-of-household was chosen as it was felt she was the most likely person to be familiar with the health and care taking of the entire family. In polygamous families, the eldest wife was selected. Interviewers were trained to conduct interviews in Portuguese or in one of the five predominant local languages. Household surveys were conducted at the end of rainy season, representing the peak malaria transmission period for that year. All analyses accounted for a stratified two-stage cluster sample design. The three outcomes of interest included whether the female heads-of-household, pregnant female heads-of-household, or children aged 0–59 months slept under a mosquito bed net during the previous night. Descriptive statistics were calculated for three oversampled districts and for the entire province. Continuous variables were reported as weighted estimates of median (interquartile range [IQR]) and categorical variables were reported as weighted percentages, with each observation being weighted by the inverse of the household or child sampling probability. Multivariable logistic regression analysis with robust covariance estimation to account for clustering was used to estimate factors associated with bed net usage for the three groups of interest. Only households from the oversampled districts were included in the regressions. Covariates were identified a priori and they included: age, education, Portuguese understanding, household size, district, whether all bed nets were donations, whether all bed nets were purchased, monthly income, travel time to health facility, household electricity, bed net distribution at current pregnancy (pregnant group only), and recent fever in child (child group only). Family income was reported in meticais (MZN) (1USD ≈ 36MZN in August 2010 and 1USD ≈ 31MZN in April 2014). If there was evidence of non-linearity (Wald test p < 0.10), continuous variables were modeled using restricted cubic splines [23, 24]. Missing values of covariates were accounted for using multiple imputation techniques. R-software 3.2.2 was used for analyses. Participation in the household surveys was completely voluntary, no incentive was provided for participation. At enrollment written informed consent was obtained. Approvals for study implementation were obtained at the national level from the National Directorate for Public Health of the Ministry of Health (Direcção Nacional de Saúde Publica) and at the Provincial level from the Provincial Health Directorate of Zambézia Province (Direcção Provincial de Saúde-Zambézia). Survey protocol, questionnaires, and informed consent documents were approved by both the Inter-institutional Committee for Bioethics in Health-Zambézia (Comité Inter-institucional de Bioética em Saude-Zambézia) and the Vanderbilt University Institutional Review Board (IRB).
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