Resistance screening and trend analysis of imported falciparum malaria in NSW, Australia (2010 to 2016)

BACKGROUND: The World Health Organization currently recommends artemisinin (along with a partner drug) as the global frontline treatment for Plasmodium falciparum malaria. Artemisinin resistant P. falciparum are now found throughout the greater Mekong subregion of South East Asia. Several polymorphisms in the parasite’s kelch gene have been demonstrated to confer artemisinin resistance. While genotypes within the greater Mekong subregion are thoroughly examined in the literature, P. falciparum populations within several areas that do not (yet) have endemic resistance are underrepresented. RESULTS: This investigation characterised the Pfkelch13 propeller domains from 153 blood samples of 140 imported cases of P. falciparum malaria in New South Wales from 2010 to 2016. A low level of propeller domain diversity was observed, including the C580Y coding mutation most strongly associated with artemisinin resistance in South East Asia. The resistance genotype was found in a sample originating in Papua New Guinea, where this mutation, or artemisinin treatment failure, have not been previously reported. Sequencing a panel of geographically informative polymorphisms within the organellar genomes identified the C580Y parasite as having Oceanic origins. Patient data analysis revealed that New South Wales, Australia, P. falciparum malaria cases often originated from regions with limited drug resistance screening. CONCLUSIONS: The C580Y finding from outside of the greater Mekong subregion supports the consensus to upscale molecular surveillance of artemisinin resistance outside of South East Asia. The genetic screening results identify a risk of importing resistant falciparum malaria to Australia, supporting an ongoing surveillance protocol to pre-empt treatment failure and contribute to global data gathering.