Plasmodium vivax is the most geographically widespread malaria parasite, with an estimated 2.5 billion people living at risk of infection in 2010. Primaquine and tafenoquine are the only antimalarial drugs that target the liver-stage parasites of P. vivax. Without treatment, these dormant parasites can trigger relapses of clinical disease in the weeks to months after the original infection. These relapses cause a cumulative burden of harm associated with increased risks of morbidity and mortality, as well as sustaining onward transmission.
Without treating the parasite liver reservoir, progress towards P. vivax elimination will remain elusive. Access to these important drugs is highly restricted by fears of triggering haemolysis in patients with a genetic glucose-6-phosphate dehydrogenase deficiency (G6PDd). To date, point-of-care access to G6PDd screening remains rare, meaning that treatment coverage is grossly insufficient. G6PDd is highly variable across malaria endemic populations, both in prevalence (commonness within a population) and severity (ranging from very mild to severe), with varied implications for the risks associated with P. vivax therapy. Documenting the characteristics of G6PDd across areas where P. vivax treatment is needed can support risk-benefit assessments for primaquine use in the absence of G6PDd testing.
MAP’s last effort to document the spatial epidemiology of G6PDd was in 2011-2013. Since then, interest in characterising G6PDd has grown substantially as the hurdles to P. vivax control have become more evident and urgent. This G6PDd data collection effort aims to build on earlier efforts, focussing both on its prevalence and genetic variants in malaria-endemic zones. Surveys are being assembled which document the characteristics of G6PDd in community-surveys as well as in malaria patients. These will inform updated geostatistical mapping of the prevalence of G6PDd.
Contributors of unpublished data to this database assembly effort are gratefully acknowledged on our site. Both the curated evidence-base and the resulting maps will be hosted in an open-access online data explorer. Funding for this programme comes from the Vivax Working Group of the Asia-Pacific Malaria Elimination Network (APMEN), itself funded by the Bill & Melinda Gates Foundation.
Two student interns contributed to this data gathering effort in July-September 2018: Jia Wei was an NDM summer intern from Peking University in Beijing, and Jonas Sandbrink is a Medical Student from Trinity College, Oxford University.