• Parasites, Hosts and Diseases
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• v.48 no.2
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• pp.175-177
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• 2010

Mixed infections of Plasmodium falciparum and Plasmodium vivax is high (~ 30%) in some malaria hypoendemic areas where the patients present with P. falciparum malaria diagnosed by microscopy. Conventional treatment of P. falciparum with concurrent chloroquine and 14 days of primaquine for all falciparum malaria patients may be useful in areas where mixed falciparum and vivax infections are high and common and also with mild or moderate G6PD deficiency in the population even with or without subpatent vivax mixed infection. It will be possibly cost-effective to reduce subsequent vivax illness if the patients have mixed vivax infection. Further study to prove this hypothesis may be warranted.

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.465-472
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• 2017

Recent trends of malaria in Thailand illustrate an increasing proportion of Plasmodium vivax, indicating the importance of P. vivax as a major causative agent of malaria. P. vivax malaria is usually considered a benign disease so the knowledge of this parasite has been limited, especially the genetic diversity and genetic structure of isolates from different endemic areas. The aim of this study was to examine the population genetics and structure of P. vivax isolates from 4 provinces with different malaria endemic settings in Thailand using 6 microsatellite markers. Total 234 blood samples from P. vivax mono-infected patients were collected. Strong genetic diversity was observed across all study sites; the expected heterozygosity values ranged from 0.5871 to 0.9033. Genetic variability in this study divided P. vivax population into 3 clusters; first was P. vivax isolates from Mae Hong Son and Kanchanaburi Provinces located on the western part of Thailand; second, Yala isolates from the south; and third, Chanthaburi isolates from the east. P. vivax isolates from patients having parasite clearance time (PCT) longer than 24 hr after the first dose of chloroquine treatment had higher diversity when compared with those having PCT within 24 hr. This study revealed a clear evidence of different population structure of P. vivax from different malaria endemic areas of Thailand. The findings provide beneficial information to malaria control programme as it is a useful tool to track the source of infections and current malaria control efforts.

• Clinical and Experimental Pediatrics
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• v.53 no.1
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• pp.85-88
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• 2010

Malaria caused by Plasmodium species is characterized by paroxysms of fever, chills, fatigue, anemia, and splenomegaly. Vivax malaria has lately re-emerged as an infectious disease and has exhibited high transmission rate in northern Gyeonggi-do province. We encountered a case of malaria in a child presenting with fever and thrombocytopenia who had recently made a school excursion to Pocheon-gun, Gyeonggi-do. The child was diagnosed with Plasmodium vivax malaria and treated with hydroxychloroquine and primaquine. Here, we present this case with a brief review of the literature.

• Parasites, Hosts and Diseases
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• v.54 no.6
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• pp.733-742
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• 2016

Acquaintance is scanty on primaquine (PQ) efficacy and Plasmodium vivax recurrence in Udupi district, Karnataka, India. We assessed the efficacy of 14 days PQ regimen (0.25 mg/kg/day) to prevent P. vivax recurrence. Microscopically, aparasitemic adults (${\geq}18years$) after acute vivax malaria on day 28 were re-enrolled into 15 months' long follow-up study. A peripheral blood smear examination was performed with participants at every 1-2 month interval. A nested PCR test was performed to confirm the mono-infection with P. vivax. Of 114 participants, 28 (24.6%) recurred subsequently. The median (IQR) duration of the first recurrence was 3.1 (2.2-5.8) months which ranged from 1.2 to 15.1 months, including initial 28 days. Participants with history of vivax malaria had significantly higher risk of recurrence, with hazard ratio (HR) (95% CI) of 2.62 (1.24-5.54) (P=0.012). Severity of disease (11.4%, 13/114) was not associated (P=1.00) with recurrence. Of 28 recurrence cases, the nPCR proved that P. vivax mono-infection recurrence rate was at least 72.7% (16/22) at first recurrence. In Udupi district, PQ dose of 0.25 mg/kg/day over 14 days seems inadequate to prevent recurrence in substantial proportion of vivax malaria. Patients with a history of vivax malaria are at high risk of recurrences.

• Parasites, Hosts and Diseases
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• v.49 no.1
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• pp.33-38
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• 2011

Prompt and accurate diagnosis of malaria is the key to prevent disease morbidity and mortality. This study was carried out to evaluate diagnostic performance of 3 commercial rapid detection tests (RDTs), i.e., Malaria Antigen Pf/Pan$^{TM}$, Malaria Ag-Pf$^{TM}$, and Malaria Ag-Pv$^{TM}$ tests, in comparison with the microscopic and PCR methods. A total of 460 blood samples microscopically positive for Plasmodium falciparum (211 samples), P. vivax (218), mixed with P. falciparum and P. vivax (30), or P. ovale (1), and 124 samples of healthy subjects or patients with other fever-related infections, were collected. The sensitivities of Malaria Ag-Pf$^{TM}$ and Malaria Antigen Pf/Pan$^{TM}$ compared with the microscopic method for P. falciparum or P. vivax detection were 97.6% and 99.0%, or 98.6% and 99.0%, respectively. The specificities of Malaria Ag-Pf$^{TM}$, Malaria Ag-Pv$^{TM}$, and Malaria Antigen Pf/Pan$^{TM}$ were 93.3%,98.8%, and 94.4%, respectively. The sensitivities of Malaria Ag-Pf$^{TM}$, Malaria Antigen Pf/Pan$^{TM}$, and microscopic method, when PCR was used as a reference method for P. falciparum or P. vivax detection were 91.8%, 100%, and 96.7%, or 91.9%,92.6%, and 97.3%, respectively. The specificities of Malaria Ag-Pf$^{TM}$, Malaria Ag-Pv$^{TM}$, Malaria Antigen Pf/Pan$^{TM}$, and microscopic method were 66.2%, 92.7%, 73.9%, and 78.2%, respectively. Results indicated that the diagnostic performances of all the commercial RDTs are satisfactory for application to malaria diagnosis.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.1.1-1.6
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• 2011

Plasmodium vivax malaria has occurred annually in the Republic of Korea (ROK) since its re-emergence in 1993. P. vivax malaria in ROK has been strongly influenced by infected mosquitoes originating from the Democratic People's Republic of Korea. Korean P. vivax malaria has shown typical characteristics of unstable malaria transmitted only during the summer season, and displays short and long incubation periods. The changing pattern of the transmission period can be predicted by analyzing the seasonal characteristics of early primary attack cases with a short incubation period. Such cases began to gradually occur earlier in the 1990s after the re-emergence. Most of the malaria cases after mid-August are presumed to be early primary attack, short incubation period cases. Only primary transmission was possible until the early 2000s, whereas up to fourth or fifth transmission occurred in the mid-2000s. The results indicate that the length of transmission period has been gradually extending, which may be ascribed to a climate change-mediated temperature rise. Malaria and climate data should be integrated to analyze and predict the influence of climate change on malaria occurrence in ROK.

• Parasites, Hosts and Diseases
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• v.53 no.3
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• pp.265-270
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• 2015

Hemoglobinopathy and malaria are commonly found worldwide particularly in malaria endemic areas. Thalassemia, the alteration of globin chain synthesis, has been reported to confer resistance against malaria. The prevalence of thalassemia was investigated in 101 malaria patients with Plasmodium falciparum and Plasmodium vivax along the Thai-Myanmar border to examine protective effect of thalassemia against severe malaria. Hemoglobin typing was performed using low pressure liquid chromatography (LPLC) and ${\alpha}$-thalassemia was confirmed by multiplex PCR. Five types of thalassemia were observed in malaria patients. The 2 major types of thalassemia were Hb E (18.8%) and ${\alpha}$-thalassemia-2 (11.9%). There was no association between thalassemia hemoglobinopathy and malaria parasitemia, an indicator of malaria disease severity. Thalassemia had no significant association with P. vivax infection, but the parasitemia in patients with coexistence of P. vivax and thalassemia was about 2-3 times lower than those with coexistence of P. falciparum and thalassemia and malaria without thalassemia. Furthermore, the parasitemia of P. vivax in patients with coexistence of Hb E showed lower value than coexistence with other types of thalassemia and malaria without coexistence. Parasitemia, hemoglobin, and hematocrit values in patients with coexistence of thalassemia other than Hb E were significantly lower than those without coexistence of thalassemia. Furthermore, parasitemia with coexistence of Hb E were 2 times lower than those with coexistence of thalassemia other than Hb E. In conclusion, the results may, at least in part, support the protective effect of thalassemia on the development of hyperparasitemia and severe anemia in malaria patients.

• Parasites, Hosts and Diseases
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• v.45 no.1 s.141
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• pp.55-58
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• 2007

Splenic infarction is a rare complication in malaria cases, and is caused primarily by Plasmodium falciparum. Recently in South Korea, only P. vivax has prevailed since 1993. Although the probability that symptomatic splenic infarction may occur in vivax malaria cases is considered relatively high, there have never been any case reports describing the occurrence of symptomatic splenic infarction in cases of vivax malaria. A 34-year-old man presented with fever that had persisted for 5 days. P. vivax infection was verified using a peripheral blood smear, and chloroquine was utilized to treat the fever successfully. Six days later, the patient developed pain in the left upper abdomen, which was diagnosed as splenic infarction by computed tomography.

• Journal of Microbiology
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• v.37 no.4
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• pp.234-242
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• 1999

To obtain the recombinant circumsporozoite (CS) protein for the diagnosis of patients and seroepidemiology of Plasmodium vivax malaria which have been prevalent in northern part of Kyonggido, the CS protein gene was amplified by the polymerase chain reaction (PCR) from genomic DNA of the Korean vivax malaria patient. The gene consists of 1,123 nucleotides except signal peptide sequences and had an uninterrupted reading frame encoding a protein of 374 amino acids with a central region of 20 tandem repeats of the nonapeptide. The CS protein gene was expressed in Escherichia coli and purified, the molecular weight of recombinant CS protein was about 44 kDa (monomer) under denaturing purification and about 65 kDa (dimer) under native purification by SDS-PAGE. The purified recombinant CS protein which has antigenicity to malaria patients in Western blot analysis and Enzyme-linked immunosorbent assay, reacted only with the serum of P. vivax (PV210) infected malaria patients with no cross reaction to the P. falciparum malaria patient. The recombinant CS protein purified in this study will serve as a useful antigen to support the diagnosis of malaria patients and seroepidemiology.

• Parasites, Hosts and Diseases
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• v.49 no.2
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• pp.125-131
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• 2011

The use of sulfadoxine and pyrimethamine (SP) for treatment of vivax malaria is uncommon in most malarious areas, but Plasmodium vivax isolates are exposed to SP because of mixed infections with other Plasmodium species. As P. vivax is the most prevalent species of human malaria parasites in Iran, monitoring of resistance of the parasite against the drug is necessary. In the present study, 50 blood samples of symptomatic patients were collected from 4 separated geographical regions of south-east Iran. Point mutations at residues 57, 58, 61, and 117 were detected by the PCR-RFLP method. Polymorphism at positions 58R, 117N, and 117T of P. vivax dihydrofolate reductase (Pvdhfr) gene has been found in 12%, 34%, and 2% of isolates, respectively. Mutation at residues F57 and T61 was not detected. Five distinct haplotypes of the Pvdhfr gene were demonstrated. The 2 most prevalent haplotypes were F57S58T61S117 (62%) and F57S58T61N117 (24%). Haplotypes with 3 and 4 point mutations were not found. The present study suggested that P. vivax in Iran is under the pressure of SP and the sensitivity level of the parasite to SP is diminishing and this fact must be considered in development of malaria control programs.