Estimating the burden of malaria and soil-transmitted helminth co-infection in sub-Saharan Africa: a geospatial study
Authors: Afolabi Muhammed O. , Adebiyi Adekola , Cano Jorge , Sartorius Benn , Greenwood Brian , Johnson Olatunji , Wariri Oghenebrume 
Published: March 2022

Background

Limited understanding exists about the interactions between malaria and soil-transmitted helminths (STH), their potential geographical overlap and the factors driving it. This study characterised the geographical and co-clustered distribution patterns of malaria and STH infections among vulnerable populations in sub-Saharan Africa (SSA).

Methodology/Principal findings

We obtained continuous estimates of malaria prevalence from the Malaria Atlas Project and STH prevalence surveys from the WHO-driven Expanded Special Project for the Elimination of NTDs (ESPEN) covering 2000-2018 and used spatial autocorrelation methods to identify statistically significant clusters for both diseases across SSA. We used the inverse distance weighted kriging (interpolation) methods to estimate STH prevalence. We calculated the population-weighted prevalence of malaria and STH co-infection, and used the bivariate local indicator of spatial association (LISA analysis) to explore potential co-clustering of both diseases at the implementation unit levels.

Our analysis shows spatial variations in the estimates of the prevalence of Plasmodium falciparum-STH co-infections and identified hotspots across many countries in SSA with inter-and intra-country variations. High P. falciparum and high hookworm co-infections were more prevalent in West and Central Africa, whereas high P. falciparum, high Ascaris lumbricoides, high P. falciparum, and high Trichuris trichiura co-infections were more predominant in Central Africa, compared to other sub-regions in SSA.

Conclusions/Significance

Wide spatial heterogeneity exists in the prevalence of malaria and STH co-infection within the regions and within countries in SSA. The geographical overlap and spatial co-existence of malaria and STH could be exploited to achieve effective control and elimination agendas through the integration of the vertical programmes designed for malaria and STH into a more comprehensive and sustainable community-based paradigm.

Author Summary

Malaria and worms frequently co-exist together among children living in the poorest countries of the world, but little is known about the specific locations of the combined infections involving the two major parasitic diseases and how they interact and change over the years.

We used open access data collected by two public registries, that is, the Malaria Atlas Project and Expanded Special Project for the Elimination of NTDs, to understand the overlap of the two diseases in different parts of Africa, where their burden are more predominant.

We found significant differences in the distributions of the combined diseases across different parts of Africa, with large concentrations identified in Central and West Africa. For example, double infections with malaria and hookworm were more common in West and Central Africa, whereas malaria and roundworm, and malaria and whipworm were predominantly found in Central Africa. A large collection of the dual infections was also found in some localities within the countries which appeared to have low burden of the two diseases.

These findings provide a useful insight into the areas which could be serving as a reservoir to propagating the transmission of the two diseases. The results of this study could also be used to develop and implement integrated control programmes for malaria and worms, and this could help to achieve the WHO NTD roadmap to ending the neglect to attain Sustainable Development Goals by 2030.