Spatial Distribution of Plasmodium falciparum and Plasmodium vivax in Northern Ethiopia by Microscopic, Rapid Diagnostic Test, Laboratory Antibody, and Antigen Data

Assessing the spatial distribution of malaria exposure using multiple metrics can improve understanding of malaria transmission dynamics in a region. In low-transmission areas, antibody data provide a useful marker to assess malaria exposure and indicate areas for further study. Background Determining malaria transmission within regions of low, heterogenous prevalence is difficult. A variety of malaria tests exist and range from identification of diagnostic infection to testing for prior exposure. This study describes the concordance of multiple malaria tests using data from a 2015 household survey conducted in Ethiopia. Methods Blood samples (n=2279) from 3 regions in northern Ethiopia were assessed for Plasmodium falciparum and Plasmodium vivax by means of microscopy, rapid diagnostic test, multiplex antigen assay, and multiplex assay for immunoglobulin G (IgG) antibodies. Geospatial analysis was conducted with spatial scan statistics and kernel density estimation to identify malaria hot spots by different test results. Results The prevalence of malaria infection was low (1.4% by rapid diagnostic test, 1.0% by microscopy, and 1.8% by laboratory antigen assay). For P. falciparum, overlapping spatial clusters for all tests and an additional 5 unique IgG clusters were identified. For P. vivax, clusters identified with bead antigen assay, microscopy, and IgG partially overlapped. Conclusions Assessing the spatial distribution of malaria exposure using multiple metrics can improve the understanding of malaria transmission dynamics in a region. The relative abundance of antibody clusters indicates that in areas of low transmission, IgG antibodies are a more useful marker to assess malaria exposure.

Automated summary

Assessing the spatial distribution of malaria exposure using multiple metrics can improve understanding of malaria transmission dynamics in a region. In low-transmission areas, antibody data provide a useful marker to assess malaria exposure. This study conducted blood sample assessments in three regions in Ethiopia, showing low prevalence of malaria infection.