Abstract
BackgroundChile 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 vector Anopheles pseudopunctipennis in previously endemic areas in Chile require an active malaria surveillance programme.MethodsSpecimens 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 confirmed Plasmodium falciparum samples and results were related to origin of infection.ResultsOut of the 268 suspected cases, 65 were Plasmodium spp. 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 for P. falciparum, 27 for Plasmodium vivax and 4 were mixed infections. The P. falciparum samples sequenced contained four mutant pfcrt genotypes (CVMNT, CVMET, CVIET and SVMNT) and three mutant pfmdr1 genotypes (Y184F/S1034C/N1042D/D1246Y, Y184F/N1042D/D1246Y and Y184F). MS analysis confirmed that all P. falciparum samples presented different haplotypes according to the suspected country of origin. Four patients with P. vivax infection returned to the health facilities due to relapses.ConclusionThe 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.
Highlights
Chile is one of the South American countries certified as malaria-free since 1945
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
Plasmodium species identified and origin of cases Microscopy analysis at the Public Health Institute of Chile (ISP) confirmed that 65 of the 268 suspected cases were positive for malaria (24.3%), 16 (24.6%) were positive for P. falciparum, 44 (67.7%) for P. vivax, 2 (3.1%) for P. ovale, and 3 (4.6%) were mixed infections (P. falciparum and P. vivax) (Fig. 1)
Summary
Chile is one of the South American countries certified as malaria-free since 1945. The four species of Plasmodium that commonly infect humans are Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. The fifth human malaria species is Plasmodium knowlesi, known to cause simian. In 2017, there were 219 million estimated cases of malaria worldwide, resulting in 435,000 deaths [3]. In South America, the most prevalent species are P. vivax and P. falciparum, with 773,000 malaria cases estimated in 2017; 97% of these cases were found in Brazil, Colombia, Peru, and Venezuela [1, 4]. Colombia and Brazil reported more confirmed cases compared to previous years, which shows an increase of the transmission in the region for this period [3, 6, 7]
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