4 research outputs found

    MEASURING ALLELIC HETEROGENEITY IN PLASMODIUM FALCIPARUM BY A HETERODUPLEX TRACKING ASSAY

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    We developed a novel Plasmodium falciparum genotyping strategy based on the heteroduplex tracking assay (HTA) method commonly used to genotype viruses. Because it can detect both sequence and size polymorphisms, we hypothesized that HTA is more sensitive than current methods. To test this hypothesis, we compared the ability of HTA and a nested polymerase chain reaction (PCR) to detect genetic diversity in 17 Thai samples. The HTA detected more MSP1 sequence variants in eight isolates (47%), less sequence variants in three isolates (18%), and an equal number of sequence variants in six isolates (35%), suggesting that HTA is equal to or more sensitive than the nested PCR. This study is a proof of concept that HTA is a sensitive allelic discrimination method able to determine genetic diversity in P. falciparum and warrants its use in studies of antimalarial drug efficacy

    Molecular screening of Plasmodium infections among migrant workers in Thailand

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    Background & objective: A cross-sectional study was conducted to determine the prevalence of Plasmodiuminfections among migrant workers in Thailand.Methods: A total of 241 migrants at Kanchanaburi, Pathumthani and Nakornpathom provinces of Thailand wererecruited in our surveillance. Blood samples were examined for human malaria parasites by using microscopyand semi-nested multiplex PCR (SnM-PCR).Results: Laboratory diagnosis revealed 6.2% total positive rate. As compared to microscopy (26.7%), SnM-PCRwas more sensitive (93.3%) for malaria. Plasmodium falciparum was predominant than P. vivax (53% : 40%,respectively). The majority of positive cases were from Myanmar workers who had low parasitaemia and withoutsymptoms. The highest prevalence (13.7%) was found among migrant workers from Kanchanaburi province inwestern Thailand.Conclusion: These findings indicate risk of malaria transmission from migrant workers. Malaria surveillanceshould be included in the health-screening program for migrants in Thailand to manage this health risk

    Asymptomatic malaria infections among foreign migrant workers in Thailand

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    AbstractObjectiveTo determine the prevalence of malaria infections among foreign migrant workers in Thailand.MethodsGiemsa-stained thin and thick blood films were prepared from blood samples of 294 foreign migrant workers recruited in the study. Microscopic examination of these blood films was performed for malaria detection.ResultsBlood film examination revealed 1.36% malaria infections in these 294 subjects. All positive cases were male Myanmar workers in which their blood films only ring stage of Plasmodium spp. was found at low parasite density (mean= 144 parasites/μ L of blood). The prevalence of malaria infections was not significantly different among foreign migrant workers classified by age, gender, and resident province (P>0.05). Thin blood films of these workers also showed 78.91% hypochromic erythrocytes and 61.9% relative Eosinophilia.ConclusionsThese findings indicate a high risk of malaria transmission. Therefore active malaria surveillance by using molecular methods with more sensitive and specific than microscopy should be considered for malaria control in foreign migrant workers

    Development of Nested PCR-Heteroduplex Mobility Assay for Determination of Genetic Diversity in the Block 2 Region of the Plasmodium falciparum Merozoite Surface Protein 1 Gene

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    Genetic diversity of Plasmodium parasite has significantly related to malaria control and vaccine development. The P. falciparum merozoite surface protein 1 (Pfmsp1) gene is a commonly used molecular marker to differentiate genetic diversity. This study is aimed at developing a nested PCR-Heteroduplex Mobility Assay (nPCR-HMA) for determination of the block 2 of the Pfmsp1 gene. The MAD20 family allele of P. falciparum was used as a control for optimization of the annealing and polyacrylamide gel electrophoresis conditions. In order to evaluate the developed nPCR-HMA, 8 clinical P. falciparum isolates were examined for allelic variants. The results revealed 9 allelic variants. Our study indicated that the successful nPCR-HMA with good precision and accuracy offers a more rapid, efficient, and cheap method for large-scale molecular epidemiological studies as compared to nucleotide sequencing
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