Relationship between unimproved household sanitation facilities and malaria infection among under-five children in Nigeria: insights from Malaria Indicator Survey 2021

Background: Malaria is a leading cause of illness and death among children under-five in sub-Saharan Africa, with Nigeria bearing the highest global malaria burden. Despite interventions such as insecticide-treated nets and indoor residual spraying, malaria prevalence remains high. While housing structure and sanitation are recognized as risk factors in other African countries, their relationship with malaria infection among under-five children in Nigeria remains underexplored. This study investigates this association using nationally representative data from the 2021 Nigeria Malaria Indicator Survey (NMIS). Methods: This study analysed data from the 2021 NMIS, including 1833 children aged 5–59 months (weighted sample size: 1,784,805,486) tested for malaria using rapid tests. Data on malaria prevention practices, household characteristics, and children’s blood samples were collected. The primary outcome was malaria test results (rapid diagnostic test, RDT), with the type of toilet facility as the main predictor. Covariates included age, sex, wealth index, maternal education, residence type, household construction materials, drinking water sources, type of mosquito nets, and mosquito net usage. Descriptive statistics and logistic regression analyses were conducted to assess associations, reporting adjusted odds ratios (aORs), 95% confidence intervals (CIs), and p-values < 0.05. Results: Children from the poorest (aOR = 3.412, 95% CI: 1.798–6.477, p = 0.0002) and poorer households (aOR = 3.103, 95% CI: 1.714–5.617, p = 0.0002) had significantly higher malaria risk. Rural residence (aOR = 1.898, 95% CI: 1.318–2.734, p = 0.0006) and no maternal education (aOR = 2.003, 95% CI: 1.153–3.480, p = 0.0139) were also associated with increased malaria prevalence. Additionally, unimproved wall materials (aOR = 1.604, 95% CI: 1.061–2.425, p = 0.025) increased malaria risk. However, unimproved sanitation facilities were not significantly associated with malaria risk (p = 0.166). Conclusion: Malaria risk among under-five children in Nigeria is strongly associated with socioeconomic factors, rural residence, and maternal education, but not unimproved sanitation alone. Efforts to reduce malaria prevalence should target broader social determinants through health education and socioeconomic interventions in Nigeria and other endemic regions.