Molecular and epidemiological characterization of imported malaria cases in Chile

Background Chile is one of the South American countries certified as malaria-free since 1945. However, the recent increase of imported malaria cases and the presence of the vectorAnopheles pseudopunctipennisin previously endemic areas in Chile require an active malaria surveillance programme. Methods Specimens from 268 suspected malaria cases-all imported-collected between 2015 and 2018 at the Public Health Institute of Chile (ISP), were diagnosed by microscopy and positive cases were included for epidemiological analysis. A photo-induced electron transfer fluorogenic primer real-time PCR (PET-PCR) was used to confirm the presence of malaria parasites in available blood samples. Sanger sequencing of drug resistance molecular markers (pfk13,pfcrt and pfmdr1) and microsatellite (MS) analysis were performed in confirmedPlasmodium falciparumsamples and results were related to origin of infection. Results Out of the 268 suspected cases, 65 werePlasmodiumspp. positive by microscopy. A total of 63% of the malaria patients were male and 37% were female; 43/65 of the patients acquired infections in South American endemic countries. Species confirmation of available blood samples by PET-PCR revealed that 15 samples were positive forP. falciparum, 27 forPlasmodium vivaxand 4 were mixed infections. TheP. falciparumsamples sequenced contained four mutantpfcrtgenotypes (CVMNT, CVMET, CVIET and SVMNT) and three mutantpfmdr1genotypes (Y184F/S1034C/N1042D/D1246Y, Y184F/N1042D/D1246Y and Y184F). MS analysis confirmed that allP. falciparumsamples presented different haplotypes according to the suspected country of origin. Four patients withP. vivaxinfection returned to the health facilities due to relapses. Conclusion The timely detection of polymorphisms associated with drug resistance will contribute to understanding if current drug policies in the country are appropriate for treatment of imported malaria cases and provide information about the most frequent resistant genotypes entering Chile.