The dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes of Plasmodium vivax, as antifolate resistance-associated genes were used for drug resistance surveillance. A total of 375 P. vivax isolates collected from different geographical locations in China in 2009-2019 were used to sequence Pvdhfr and Pvdhps. The majority of the isolates harbored a mutant type allele for Pvdhfr (94.5%) and Pvdhps (68.2%). The most predominant point mutations were S117T/N (77.7%) in Pvdhfr and A383G (66.8%) in Pvdhps. Amino acid changes were identified at nine residues in Pvdhfr. A quadruple-mutant haplotype at 57, 58, 61, and 117 was the most frequent (57.4%) among 16 distinct Pvdhfr haplotypes. Mutations in Pvdhps were detected at six codons, and the double-mutant A383G/A553G was the most prevalent (39.3%). Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China. Most isolates from Yunnan carried multiple mutant haplotypes, while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type. This study indicated that the antifolate resistance levels of P. vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance. Results provided evidence for updating national drug policy and treatment guidelines.
Antimalarials/pharmacology* ; China/epidemiology* ; Drug Combinations ; Drug Resistance/genetics* ; Folic Acid Antagonists/pharmacology* ; Humans ; Mutation ; Plasmodium vivax/genetics* ; Prevalence

In malaria, splenic rupture is a serious complication potentially leading to death. Subcapsular hemorrhage of spleen is thought to be an impending sign of splenic rupture; however, the characteristics of subcapsular hemorrhage are not well known. We report 3 cases of subcapsular hemorrhage of the spleen in vivax malaria, with varying degrees of severity. Case 1 showed subcapsular hemorrhage without splenic rupture, was treated by antimalarial drug without any procedure. The healing process of the patient's spleen was monitored through 6 computed tomography follow-up examinations, over 118 days. Case 2 presented subcapsular hemorrhage with splenic rupture, treated only with an antimalarial drug. Case 3 showed subcapsular hemorrhage with splenic rupture and hypotension, treated using splenic artery embolization. They all recovered from subcapsular hemorrhage without any other complications. These 3 cases reveal the process of subcapsular hemorrhage leading to rupture and a potentially fatal outcome. The treatment plan of subcapsular hemorrhage should be determined carefully considering the vital signs, changes in hemoglobin, and bleeding tendency.
Fatal Outcome ; Follow-Up Studies ; Hemorrhage ; Hypotension ; Malaria ; Malaria, Vivax ; Plasmodium vivax ; Rupture ; Spleen ; Splenic Artery ; Splenic Rupture ; Vital Signs

Plasmodium vivax is usually considered morbidity in endemic areas of Asia, Central and South America, and some part of Africa. In Thailand, previous studies indicated the genetic diversity of P. vivax in malaria-endemic regions such as the western part of Thailand bordering with Myanmar. The objective of the study is to investigate the genetic diversity of P. vivax circulating in Southern Thailand by using 3 antigenic markers and 8 microsatellite markers. Dried blood spots were collected from Chumphon, Phang Nga, Ranong and, Surat Thani provinces of Thailand. By PCR, 3 distinct sizes of PvMSP3α, 2 sizes of PvMSP3β and 2 sizes of PvMSP1 F2 were detected based on the length of PCR products, respectively. PCR/RFLP analyses of these antigen genes revealed high levels of genetic diversity. The genotyping of 8 microsatellite loci showed high genetic diversity as indicated by high alleles per locus and high expected heterozygosity (H(E)). The genotyping markers also showed multiple-clones of infection. Mixed genotypes were detected in 4.8% of PvMSP3α, 29.1% in PvMSP3β and 55.3% of microsatellite markers. These results showed that there was high genetic diversity of P. vivax isolated from Southern Thailand, indicating that the genetic diversity of P. vivax in this region was comparable to those observed other areas of Thailand.
Africa ; Alleles ; Asia, Central ; Genetic Variation ; Genotype ; Malaria ; Microsatellite Repeats ; Myanmar ; Plasmodium vivax ; Plasmodium ; Polymerase Chain Reaction ; South America ; Thailand

No abstract available.
Blood Cell Count* ; Plasmodium vivax* ; Plasmodium*

Molecular techniques have been introduced for malaria diagnosis because they offer greater sensitivity and specificity than microscopic examinations. Therefore, DNA isolation methods have been developed for easy preparation and cost effectiveness. The present study described a simple protocol for Plasmodium DNA isolation from EDTA-whole blood. This study demonstrated that after heating infected blood samples with Tris–EDTA buffer and proteinase K solution, without isolation and purification steps, the supernatant can be used as a DNA template for amplification by PCR. The sensitivity of the extracted DNA of Plasmodium falciparum and Plasmodium vivax was separately analyzed by both PCR and semi-nested PCR (Sn-PCR). The results revealed that for PCR the limit of detection was 40 parasites/μl for P. falciparum and 35.2 parasites/μl for P. vivax, whereas for Sn-PCR the limit of detection was 1.6 parasites/μl for P. falciparum and 1.4 parasites/μl for P. vivax. This new method was then verified by DNA extraction of whole blood from 11 asymptomatic Myanmar migrant workers and analyzed by Sn-PCR. The results revealed that DNA can be extracted from all samples, and there were 2 positive samples for Plasmodium (P. falciparum and P. vivax). Therefore, the protocol can be an alternative method for DNA extraction in laboratories with limited resources and a lack of trained technicians for malaria diagnosis. In addition, this protocol can be applied for subclinical cases, and this will be helpful for epidemiology and control.
Cost-Benefit Analysis ; Diagnosis ; DNA ; Edetic Acid ; Endopeptidase K ; Epidemiology ; Heating ; Hot Temperature ; Humans ; Limit of Detection ; Malaria ; Methods ; Myanmar ; Plasmodium falciparum ; Plasmodium vivax ; Plasmodium ; Polymerase Chain Reaction ; Sensitivity and Specificity ; Transients and Migrants

Malaria is one of the most important public health problems in tropical areas on the globe. Several factors are associated with susceptibility to malaria and disease severity, including innate immunity such as blood group, hemoglobinopathy, and heme oxygenase-1 (HO-1) polymorphisms. This study was carried out to investigate association among ABO blood group, thalassemia types and HO-1 polymorphisms in malaria. The malarial blood samples were collected from patients along the Thai-Myanmar border. Determination of ABO blood group, thalassemia variants, and HO-1 polymorphisms were performed using agglutination test, low pressure liquid chromatography and polymerase chain reaction, respectively. Plasmodium vivax was the major infected malaria species in the study samples. Distribution of ABO blood type in the malaria-infected samples was similar to that in healthy subjects, of which blood type O being most prevalent. Association between blood group A and decreased risk of severe malaria was significant. Six thalassemia types (30%) were detected, i.e., hemoglobin E (HbE), β-thalassemia, α-thalassemia 1, α-thalassemia 2, HbE with α-thalassemia 2, and β-thalassemia with α-thalassemia 2. Malaria infected samples without thalassemia showed significantly higher risk to severe malaria. The prevalence of HO-1 polymorphisms, S/S, S/L and L/L were 25, 62, and 13%, respectively. Further study with larger sample size is required to confirm the impact of these 3 host genetic factors in malaria patients.
Agglutination Tests ; Blood Group Antigens ; Chromatography, Liquid ; Healthy Volunteers ; Heme Oxygenase (Decyclizing) ; Heme Oxygenase-1 ; Heme ; Hemoglobin E ; Hemoglobinopathies ; Hemoglobins ; Humans ; Immunity, Innate ; Malaria ; Plasmodium vivax ; Polymerase Chain Reaction ; Prevalence ; Public Health ; Sample Size ; Thalassemia

Plasmodium vivax is more challenging to control and eliminate than P. falciparum due to its more asymptomatic infections with low parasite densities making diagnosis more difficult, in addition to its unique biological characteristics. The potential re-introduction of incidence cases, either through borders or via human migrations, is another major hurdle to sustained control and elimination. The Republic of Korea has experienced re-emergence of vivax malaria in 1993 but is one of the 32 malaria-eliminating countries to-date. Despite achieving successful nationwide control and elimination of vivax malaria, the evolutionary characteristics of vivax malaria isolates in the Republic of Korea have not been fully understood. In this review, we present an overview of the genetic variability of such isolates to increase understanding of the epidemiology, diversity, and dynamics of vivax populations in the Republic of Korea.
Asymptomatic Infections ; Diagnosis ; Epidemiology ; Genetic Variation ; Human Migration ; Incidence ; Korea ; Malaria ; Malaria, Vivax ; Parasites ; Plasmodium vivax ; Plasmodium ; Population Characteristics ; Republic of Korea

Historically, Plasmodium vivax malaria has been one of the most highly endemic parasitic diseases in the Korean Peninsula. Until the 1970s, vivax malaria was rarely directly lethal and was controlled through the Korean Government Program administered by the National Malaria Eradication Service in association with the World Health Organization's Global Malaria Eradication Program. Vivax malaria has re-emerged in 1993 near the Demilitarized Zone between South and North Korea and has since become an endemic infectious disease that now poses a serious public health threat through local transmission in the Republic of Korea. This review presents major lessons learned from past and current malaria research, including epidemiological and biological characteristics of the re-emergent disease, and considers some interesting patterns of diversity. Among other features, this review highlights temporal changes in the genetic makeup of the parasitic population, patient demographic features, and spatial distribution of cases, which all provide insight into the factors contributing to local transmission. The data indicate that vivax malaria in Korea is not expanding exponentially. However, continued surveillance is needed to prevent future resurgence.
Communicable Diseases ; Culicidae ; Democratic People's Republic of Korea ; Global Health ; Government Programs ; Humans ; Korea ; Malaria ; Malaria, Vivax ; Parasitic Diseases ; Plasmodium vivax ; Population Characteristics ; Public Health ; Republic of Korea

Vivax malaria reemerged in Korea in 1993 and the outbreak has been continued with fluctuating numbers of annual indigenous cases. Understanding the nature of the genetic population of Plasmodium vivax circulating in Korea is beneficial for the knowledge of the nationwide parasite heterogeneity and in the implementation of malaria control programs in the country. Previously, we analyzed polymorphic nature of merozoite surface protein-1 (MSP-1) and MSP-3α in Korean P. vivax population and identified the Korean P. vivax population has been diversifying rapidly, with the appearance of parasites with new genetic subtypes, despite the recent reduction of the disease incidence. In the present study, we developed simple PCR-RFLP methods for rapid subtyping of MSP-1 and MSP-3α of Korean P. vivax isolates. These PCR-RFLP methods were able to easily distinguish each subtype of Korean P. vivax MSP-1 and MSP-3α with high accuracy. The PCR-RFLP subtyping methods developed here would be easily applied to massive epidemiological studies for molecular surveillance to understand genetic population of P. vivax and to supervise the genetic variation of the parasite circulating in Korea.
Epidemiologic Studies ; Genetic Variation ; Incidence ; Korea ; Malaria ; Malaria, Vivax ; Merozoite Surface Protein 1 ; Parasites ; Plasmodium vivax* ; Plasmodium* ; Population Characteristics

Variant surface antigens (VSAs) encoded by pir families are considered to be the key proteins used by many Plasmodium spp. to escape the host immune system by antigenic variation. This attribute of VSAs is a critical issue in the development of a novel vaccine. In this regard, a population genetic study of vir genes from Plasmodium vivax was performed in the Republic of Korea (ROK). Eighty-five venous blood samples and 4 of the vir genes, namely vir 27, vir 21, vir 12, and vir 4, were selected for study. The number of segregating sites (S), number of haplotypes (H), haplotype diversity (Hd), DNA diversity (π and Θw), and Tajima’s D test value were conducted. Phylogenetic trees of each gene were constructed. The vir 21 (S=143, H=22, Hd=0.827) was the most genetically diverse gene, and the vir 4 (S=6, H=4, Hd=0.556) was the opposite one. Tajima’s D values for vir 27 (1.08530, P>0.1), vir 12 (2.89007, P<0.01), and vir 21 (0.40782, P>0.1) were positive, and that of vir 4 (−1.32162, P>0.1) was negative. All phylogenetic trees showed 2 clades with no particular branching according to the geographical differences and cluster. This study is the first survey on the vir genes in ROK, providing information on the genetic level. The sample sequences from vir 4 showed a clear difference to the Sal-1 reference gene sequence, whereas they were very similar to those from Indian isolates.
Antigenic Variation ; Antigens, Surface ; DNA ; Genetic Variation ; Haplotypes ; Humans ; Immune System ; Plasmodium vivax* ; Plasmodium* ; Republic of Korea* ; Trees ; United Nations