Molecular and epidemiological characterization of imported malaria cases in Chile

Abstract

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 vector Anopheles pseudopunctipennis in 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 confirmed Plasmodium falciparum samples and results were related to origin of infection. Results: Out 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. 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.

A cross-sectional study of the prevalence, density, and risk factors associated with malaria transmission in urban communities of Ibadan, Southwestern Nigeria

“…Additionally, the sex pattern of infection in this study shows that males have higher malaria prevalence and mean parasite density than their female colleagues. This is related to previous reports from other studies in malaria-endemic areas such as Ethiopia and Chile [ 28 , 29 ]. This could be because males usually get involved in outdoor activities, stay late until night outside, have a lackadaisical attitude towards malaria prevention and farming, which inadvertently exposes them to high mosquito bites than females.…”

A cross-sectional study of the prevalence, density and risk factors associated with malaria transmission in urban communities of Ibadan, Southwestern Nigeria

“…Additionally, the sex pattern of infection in this study showed that males had higher malaria prevalence and mean parasite density compared to their female colleagues. This is related and comparable to previous reports from other studies in malaria endemic areas [25,26]. This could be due to the fact that males usually get involve in outdoor activities, staying late until night outside, have lackadaisical attitude towards malaria prevention and farming which inadvertently expose them to high mosquito bites than females.…”

Diagnostic Methods for Non-Falciparum Malaria

“…The limits of detection were 5.8 parasites/mL for Po, 3.5 parasites/mL for Pm and 5 parasites/mL for Pv using the genus-specific primer set (Lucchi et al, 2013). The sensitivity and specificity of this method were field-validated with samples from different regions, demonstrating similar performance to nested-PCR, while less expensive and easier to use (Talundzic et al, 2014;Escobar et al, 2020).…”