Latest release of Molecular Surveyor with pfcrt and pfmdr1 genes

Plasmodium falciparum parasites have repeatedly evolved to develop resistance against first-line antimalarial drugs, frustrating global efforts to control and eventually eliminate this deadly disease. Resistance to the current frontline antimalarial treatments, artemisinin combination therapies or ACTs, has now emerged or spread in the Mekong region of Southeast Asia.

Fortunately the latest technology can help to track the spread of antimalarial drug resistance by identifying molecular markers, the genetic changes in the DNA of the malaria parasite associated with drug resistance.  Identifying and tracking these molecular markers can provide evidence for public health experts as they develop strategies to slow the spread or emergence of drug resistance and prolong the effectiveness of these important treatments.

WWARN’s Molecular Surveyor is an interactive map that summarises the location and prevalence of the molecular markers associated with resistance to particular drugs throughout the world. This tool allows researchers and policy makers to visualise these data by providing a useful map presentation of the prevalence of molecular markers of resistance in the malaria parasites.  Changes over time in the prevalence of a resistance marker can act as an early warning of reduced susceptibility of those parasites to a particular antimalarial.

The Molecular Surveyor is an interactive map that summarises the location and prevalence of molecular markers associated with antimalarial drug resistance

The surveyor has now been expanded to display markers of antimalarial resistance within the genes pfcrt and pfmdr1. These genetic markers are associated with reduced susceptibility of the malaria parasite to chloroquine, amodiaquine and lumefantrine – two of which are partner drugs in the ACTs, artemether lumefantrine and artesunate- amodiaquine.

 “The latest release of the Molecular Surveyor provides the research community with the most comprehensive picture yet of the spatio-temporal trends of molecular markers of resistance throughout the world – a key surveillance tool in the fight against antimalarial resistance,” says Prof Carol Hopkins Sibley, WWARN’s Scientific Director. “This interactive tool will help to highlight where and how we need to focus our efforts in understanding the spread and emergence of parasites resistant to these widely used ACTs.”

This Molecular Surveyor now summarises data from more than 300 published and unpublished studies since 2006, examining data on these molecular markers of antimalarial resistance from approximately 200 international locations.  The colour code of the pins and the use of filters can give a quick summary of the status of marker prevalence, allowing the output from individual studies to be compared at a glance across the world.

“The updated version of the WWARN Molecular Surveyor is an important tool for the malaria research community. It has the potential to identify the gaps in our knowledge of antimalarial drug resistance,” says Dr Colin Sutherland from the London School of Tropical Medicine and Hygiene. “For certain countries, we know little about the efficacy of malaria drugs in those countries, nor about the prevalence of markers of antimalarial resistance. This tool can be used to help us develop better designed, strategically placed molecular studies so we stay ahead of antimalarial resistance in Africa and across the malaria endemic world.”  

The research community can investigate in more detail, searching by country, drug or type of study.

A previous version of the Molecular Surveyor displayed resistance markers for sulphadoxine pyrimethamine found on genes, dhfr and dhps, and this map is still available.

The data that underlie the Molecular Surveyor  can be downloaded as a fully searchable Access database. The summary and reference tables display further detailed information about all the studies selected within the Surveyor.

The Molecular Surveyor complements the WWARN Explorer, which is powered by individual patient level data. 

Did you know? Access to the code that powers some of our interactive mapping tools - such as the WWARN Molecular Surveyor, Antimalarial Quality Surveyor and the WWARN Explorer  is now open source. Please email our Informatics Team for more information on how to access this open source code: informatics@wwarn.org

Have you read WWARN’s latest pooled analysis on the association between these molecular markers and treatment outcome of two widely used ACTs?

Meera Venkatesan et al.  (And the more than 50 authors in the molecular marker study group) Polymorphisms in Plasmodium falciparum Chloroquine Resistance Transporter and Multidrug Resistance 1 Genes: Parasite Risk Factors that Affect Treatment Outcomes for P. falciparum Malaria after Artemether-Lumefantrine and Artesunate-Amodiaquine Advanced online publication in American Journal of Tropical Medicine doi:10.4269/ajtmh.14-0031