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NEW THIS THURSDAY: A STICKY SITUATION, THE UNEXPECTED STABILITY OF MALARIA ELIMINATION

Thursday, 11th of July 2013

• A STICKY SITUATION: THE UNEXPECTED STABILITY OF MALARIA ELIMINATION

 

David L. Smith1,2,3,4,5, Justin M. Cohen6, Christinah Chiyaka3,

Geoffrey Johnston1,2,3, Peter W. Gething7, Roly Gosling8, Caroline O. Buckee9,

Ramanan Laxminarayan4, Simon I. Hay5,7 and Andrew J. Tatem5,10

1Department of Epidemiology, and 2Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA

3Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA

4Center for Disease Dynamics, Economics and Policy, Washington, DC, USA

5Fogarty International Center, NIH, Bethesda, MD, USA

6Clinton Health Access Initiative, Boston, MA, USA

7Spatial Ecology, Department of Zoology, University of Oxford, Oxford, UK

8Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, CA, USA

9Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA

10Department of Geography and Environment, University of Southampton, Highfield, Southampton, UK

 

 

Abstract below; full text is at http://rstb.royalsocietypublishing.org/content/368/1623/20120145.full.pdf+html

 

Malaria eradication involves eliminating malaria from every country where transmission occurs. Current theory suggests that the post-elimination challenges

of remaining malaria-free by stopping transmission from imported malaria will have onerous operational and financial requirements. Although

resurgent malaria has occurred in a majority of countries that tried but failed to eliminate malaria, a review of resurgence in countries that successfully

eliminated finds only four such failures out of 50 successful programmes.

 

Data documenting malaria importation and onwards transmission in these countries suggests malaria transmission potential has declined by more

than 50-fold (i.e. more than 98%) since before elimination. These outcomes suggest that elimination is a surprisingly stable state. Elimination’s

‘stickiness’ must be explained either by eliminating countries starting off qualitatively different from non-eliminating countries or becoming different

once elimination was achieved. Countries that successfully eliminated were wealthier and had lower baseline endemicity than those that were unsuccessful,

but our analysis shows that those same variables were at best incomplete predictors of the patterns of resurgence. Stability is reinforced by the loss of immunity to disease and by the health system’s increasing capacity to control malaria transmission after elimination through routine treatment of cases with antimalarial drugs supplemented by malaria outbreak control. Human travel patterns reinforce these patterns; as malaria recedes, fewer people carry malaria from remote endemic areas to remote areas where transmission potential remains high. Establishment of an international resource with backup capacity to control large outbreaks can make elimination stickier, increase the incentives for countries to eliminate, and ensure steady progress towards global eradication. Although available

evidence supports malaria elimination’s stickiness at moderate-to-low transmission in areas with well-developed health systems, it is not yet clear if

such patterns will hold in all areas. The sticky endpoint changes the projected costs of maintaining elimination and makes it substantially more

attractive for countries acting alone, and it makes spatially progressive elimination a sensible strategy for a malaria eradication endgame.

 

2013 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0/, which permits unrestricted use, provided the original author and source are credited.