Insecticide-Treated Net Coverage in Africa

Global Malaria Epidemiology

ITNs are a crucial malaria prevention tool in Africa, with both malaria policy decisions and quantitative analyses often requiring a detailed understanding of ITN coverage over both space and time. Fully characterizing ITN coverage is challenging: in order to arrive in households, nets must travel through unique supply chain, and once in households they intersect with human behavior and malaria risk in a nuanced way over multiple years. Because nets are such a major malaria commodity, every step of this process has major implications for the cost-effectiveness of this intervention. Additionally, there are a number of different ways to conceptualize ITN coverage: who has access to a net, who actually uses nets they have access to, and how many nets are available in the population as a whole. Each of these metrics is valuable to different stakeholders for different reasons.

In this study, we generate high-resolution maps of ITN access, use, and nets-per-capita annually from 2000 to 2020 across the 40 highest-burden African countries. Our findings support several existing hypotheses: that use is high among those with access, that nets are discarded more quickly than official policy presumes, and that effectively distributing nets grows more difficult as coverage increases. The primary driving factors behind these findings are most likely strong cultural and social messaging around the importance of net use, low physical net durability, and a mixture of inherent commodity distribution challenges and less-than-optimal net allocation policies, respectively.

These results may be used in a number of ways. By filling in gaps in both space and time between surveys, we produce a complete picture of net coverage over the past 20 years that may be valuable for policy-makers at international, national, and subnational scales. When planning future campaigns, these policy-makers may also find utility in our results highlighting important allocative inefficiencies in net distribution. By estimating net retention times on the national level, we lend support to arguments for supply-side reconsiderations of net durability and quality control. Finally, by making all results and code publicly available, we facilitate information-sharing and use of these results by any public health professional or quantitative researcher who may wish to conduct analyses of their own.

#
 
Collaborators

This work was done in collaboration with:

  • The Institute for Disease Modeling, Seattle, WA, USA.
  • Tropical Health, Baltimore, MD, USA
  • Section of Epidemiology, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
  • Department of Infectious Disease Epidemiology, Imperial College London, London, UK
  • Alliance for Malaria Prevention Net Mapping Project
  • African Leaders Malaria Alliance

#
 
Results

Visualise the results using the Exceedance Surfaces Explorer.

Download the surfaces with the following links. Please note that these downloads are large and may take some time to complete.

#
 
Full Citation

Bertozzi-Villa A., Bever CA., Koenker H., Weiss DJ., Vargas-Ruiz C., Nandi AK., Gibson HS., Harris JR., Battle KE., Rumisha SF., Keddie S., Amratia P., Arambepola R., Cameron E., Chestnutt EG., Collins EL., Millar J., Mishra S., Rozier J., Symons TL., Twohig KA., Hollingsworth TD., Gething PW. & Bhatt S., Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020. (2020). Nat Commun 12, 3589 (2021). https://doi.org/10.1038/s41467-021-23707-7