Risk Factors and Geospatial Associations With Plasmodium falciparum Malaria Infection and IgG Seroprevalence: Nigeria, 2018.

BACKGROUND

Nigeria consistently shows the greatest population burden of Plasmodium falciparum (Pf) malaria. While rapid diagnostic tests and microscopy offer valuable information for clinical decisions and prevalence estimates, serological tools provide more nuanced information on exposure history, enhancing the ability to assess and track malaria burden at a population level.

METHODS

Blood samples (n = 89 438) from a nationwide 2018 human immunodeficiency virus household survey in Nigeria were assayed for active/recent infection by testing for the Pf HRP2 and LDH antigens, and for Pf exposure by immunoglobulin G carriage against a panel of antigens. Risk factors for Pf infection and exposure were assessed using logistic regression and geospatial analyses.

RESULTS

By blood antigenemia, current/recent Pf prevalence was 38.3% (95% CI: 37.2%-39.5%), and seroprevalence among the panel of 5 Pf antigens ranged from 48% to 87%. In multivariate regression models, participants age 5-14 years had the highest odds of active infection versus children <5 years. Compared with the lowest wealth category, the wealthiest category showed a 5-fold reduction in odds of active infection, and urban living was associated with a 30% reduction. In estimating a longer window of Pf exposure, serology recapitulated these associations with the highest wealth category showing a 10-fold reduction, and urban living a 60% reduction, in exposure.

CONCLUSIONS

Geospatial findings underscored Nigeria's hyperendemic but heterogeneous malaria epidemiology with infection and exposure are not unequally distributed among the populace. Serological data can provide greater insights into malaria risk factor analyses and augment examination of spatial heterogeneities in transmission.