Strengthening the practical value of molecular resistance markers in public health

A two-year collaboration involving scientists from Oxford, London, Bangkok, Durban, Bogota and Maryland has resulted in an innovative way of viewing molecular markers of antimalarial resistance.

The WWARN Molecular Surveyor brings into one place summary molecular data from hundreds of publications across several decades.  For each resistance marker, the sample size and number of isolates carrying that marker are presented, along with the site name, year of data collection and link to the publication. The search function displays results in interactive maps, which can be filtered by time and sample size.  The tool complements WWARN Explorer, which is powered by individual patient level data.  

Covering Africa, Asia and Latin America, Molecular Surveyor includes data on resistance markers for sulphadoxine-pyrimethamine (SP) found in Plasmodium falciparum dhfr and dhps genes. The current focus is on the use of SP in intermittent preventive therapy, recently recommended by the WHO for infants in sub-Saharan Africa, specifically in regions below a defined molecular resistance threshold.  

The project is coordinated by researchers from WWARN's Molecular Module, based at the University of Maryland, and Informatics Module, based in Oxford.  The research was initiated by Drs Cally Roper and Inbarani Naidoo at the London School of Hygiene and Tropical Medicine and the South African Medical Research Council, who systematically compiled data on resistance markers throughout Africa. This collaboration expanded to include data collected by Dr Mallika Imwong at Mahidol University, Thailand and Dr Vladimir Corredor at the Universidad Nacional de Colombia.  

“From the outset, our aim was to demonstrate the practical value of molecular resistance markers in public health", explains Dr Roper.  "There was a wealth of information in the literature describing molecular surveys carried out at hundreds of malaria endemic locations, but it is only by summarising and mapping this information, that the practical utility for national malaria control programs and policy makers can be realised."

Plans for expansion of Molecular Surveyor include the addition of other markers of antimalarial resistance including pfcrt and pfmdr1 haplotypes. dhfr/dhps haplotypes will also be added when they are available in the literature, in addition to the current maps of individual dhfr and dhps mutations.  

Molecular Surveyor can be viewed through the WWARN website. Scientists interested in joining this project should contact molecular@wwarn.org