Failure of Antimalarials in Cambodia
With new mosquito-borne diseases such as Zika and Mayaro grabbing headlines, malaria gets little attention in 2016. In the last 15 years new cases have dropped 37% globally and global deaths have dropped by 60%1. Sri Lanka made the news in September as the most recent country to successfully eliminate malaria. But what perhaps is not getting enough attention is the growing resistance to antimalarial drugs.
The current frontline treatment for p.falciparum, the most deadly malaria parasite, is artemisinin combination therapies (ACTs). P.faciparum resistance to artemisinin is not a new problem, and has been emerged independently in several countries in Southeast Asia1. The combinations of drugs used in ACTs are usually still effective in killing the malaria parasite. But in Cambodia, p.falciparum has now developed resistance to piperaquine, a powerful complement combination drug. The newly developed resistance results in a failure of malaria treatments and drastically increases the threat of spreading resistance. Piperaquine efficacy in Cambodia declined quickly after its introduction. The rapid spread in resistance is alarming to neighboring countries and could be catastrophic if it reaches Africa where 90% of malaria deaths occur. There is additional concern that artemisinin resistance will accelerate resistance to partner drugs.
Scientists have discovered that resistant parasites seem to be susceptible to mefloquine, an older antimalarial drug that is currently suggested as the new frontline treatment in areas with documented piperaquine resistance. Cycling of various combination therapies as well as new antimalarial compounds are urgently needed to prevent growing resistance.
Unique genetic markers have been identified in the resistant parasites that should be useful in tracking resistance and aiding in the creation of data mapping and visualization tools for improved surveillance strategies. Improved rapid tests detecting resistance will also allow physicians to prescribe the correct antimalarial regime and combat spreading resistance.
1 http://www.who.int/mediacentre/factsheets/fs094/en/
2 http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(15)00487-9/fulltext
3 http://www.bbc.com/news/health-37859264