• Parasites, Hosts and Diseases
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• v.54 no.4
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• pp.399-405
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• 2016

Poor subsistence farmers who live in a semi-arid area of northern Ethiopia build irrigation systems to overcome water shortages. However, there is a high risk of malaria transmission when increased standing water provides more favorable habitats for mosquito breeding. This is a serious problem because there are many barriers to malaria control measures and health care systems in the area. Using a causal loop diagram and computer simulations, the author attempted to visually illustrate positive and negative feedbacks between mosquito and human populations in the context of Simret, which is a small village located in northern Ethiopia and is generally considered a malaria-free area. The simulation results show that the number of infectious mosquitos increases to 17,215 at its peak, accounting for 3.5% of potentially dangerous mosquitos. At the same time, the number of sick people increases to 574 at its peak, accounting for 15% of local population. The malaria outbreak is controlled largely because of a fixed number of vulnerable people or local population that acts as an intermediate host.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.295-299
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• 2022

Malaria elimination and control require prompt and accurate diagnosis for treatment plan. Since microscopy and rapid diagnostic test (RDT) are not sensitive particularly for diagnosing low parasitemia, highly sensitive diagnostic tools are required for accurate treatment. Molecular diagnosis of malaria is commonly carried out by nested polymerase chain reaction (PCR) targeting 18S rRNA gene, while this technique involves long turnaround time and multiple steps leading to false positive results. To overcome these drawbacks, we compared highly sensitive cytochrome oxidase gene-based single-step multiplex reaction with 18S rRNA nested PCR. Cytochrome oxidase (cox) genes of P. falciparum (cox-III) and P. vivax (cox-I) were compared with 18S rRNA gene nested PCR and microscopy. Cox gene multiplex PCR was found to be highly specific and sensitive, enhancing the detection limit of mixed infections. Cox gene multiplex PCR showed a sensitivity of 100% and a specificity of 97%. This approach can be used as an alternative diagnostic method as it offers higher diagnostic performance and is amenable to high throughput scaling up for a larger sample size at low cost.

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.72-77
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• 1984

A case of congenital malaria infection has been studied in a 46-day old female Korean infant. Her mother suffered from malaria infection during pregnancy in Uppervolta, Africa, and returned to Korea at the 9th month of gestation for delivery. At 39 days of age, the clinical features characterized by fever, irritability, pallor, jaundice and hepatosplenomegaly were developed. The laboratory data revealed a hemolytic anemia with thronbocytopenia, hyperbilirubinemia and increased hepatic enzyme values. A peripheral blood smear demonstrated intraerythrocytic malarial parasites and gametocytes of Plasmodium falciparum. She was successfully treated with quinine solfate (25mg/kg/day in three doses for 5 days) and trimethoprimejsulfamethoxazole (8mg/kg/day in two doses for 5 days) orally, and repeated blood smear had been negative for malaria. This report also signifies the first description of congenital malaria in Korea imported from Uppervolta in Africa. A brief review of related literature was made.

• 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.

• Korean Journal of Pharmacognosy
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• v.43 no.3
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• pp.239-242
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• 2012

This study was carried out to investigate the anti-malarial activity of Juniperus chinensis by in vitro and in vivo system using Plasmodium falciparum chloroquine-sensitive(3D7) and P. falciparum chloroquine-resistant(S20) strains. According to cytotoxicty test on NIH 3T3 cell, the ethanol extract(EtOH), ethylacetate(EtOAc) fraction and aqueous fraction possessed significant anti-malarial activity against both 3D7 and S20 strains at non-toxic concentrations(<100 /). In vitro assay, EtOAc fraction showed notable activity against 3D7 and S20 strains of P. falciparum with $IC_{50}$ values of $37{\pm}2{\mu}g/ml$ and $36{\pm}6{\mu}g/ml$. In animal test using P. falciparum infected human erythrocytes, the treatment of EtOAc fraction significantly inhibited parasitaemia in mice in a dose-dependent manner that is parasitaemia of 42%, 34% and 31% in doses of 10 mg/kg, 20 mg/kg and 40 mg/kg, respectively. The study provides data to support the medicinal importance of the J. chinensis.

• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.253-259
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• 2016

In the era of (pre) elimination setting, the prevalence of malaria has been decreasing in most of the previously endemic areas. Therefore, effective cost- and time-saving validated pooling strategy is needed for detection of malaria in low transmission settings. In this study, optimal pooling numbers and lowest detection limit were assessed using known density samples prepared systematically, followed by genomic DNA extraction and nested PCR. Pooling strategy that composed of 10 samples in 1 pool, $20{\mu}l$ in 1 sample, was optimal, and the parasite density as low as $2p/{\mu}l$ for both falciparum and vivax infection was enough for detection of malaria. This pooling method showed effectiveness for handling of a huge number of samples in low transmission settings (<9% positive rate). The results indicated that pooling of the blood samples before DNA extraction followed by usual nested PCR is useful and effective for detection of malaria in screening of hidden cases in low-transmission settings.

• Parasites, Hosts and Diseases
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• v.44 no.1 s.137
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• pp.49-54
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• 2006

In order to develop tools for an early serodiagnosis of Plasmodium falciparum infection, we evaluated the usefulness of P. falciparum liver stage antigen-3 (LSA-3) as a serodiagnostic antigen. A portion of LSA-3 gene was cloned, and its recombinant protein (rLSA-3) was expressed in Escherichia coli and purified by column chromatography. The purified rLSA-3 and 120 test blood/serum samples collected from inhabitants in malaria-endemic areas of Mandalay, Myanmar were used for this study. In microscopic examinations of blood samples, P. falciparum positive rate was $39.1\%$ (47/120) in thin smear trials, and $33.3\%$ (40/120) in thick smear trials. Although the positive rate associated with the rLSA-3 $(30.8\%)$ was lower than that of the blood stage antigens $(70.8\%)$, rLSA-3 based enzyme-linked immunosorbent assay could detect 12 seropositive cases $(10.0\%),$ in which blood stage antigens were not detected. These results indicate that the LSA-3 is a useful antigen for an early serodiagnosis of P. falciparum infection.

• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.261-264
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• 2016

As endemic malaria is not commonly seen in the United States, most of the cases diagnosed and reported are associated with travel to and from the endemic places of malaria. As the number of imported cases of malaria has been increasing since 1973, it is important to look into these cases to study the morbidity and mortality associated with this disease in the United States. In this study, we would like to share our experience in diagnosing and treating these patients at our institution. We did a retrospective chart review of 37 cases with a documented history of imported malaria from 1998 to 2012. Among them, 16 patients had complicated malaria during that study period, with a mean length of hospital stay of 3.5 days. Most common place of travel was Africa, and chemoprophylaxis was taken by only 11% of patients. Travel history plays a critical role in suspecting the diagnosis and in initiating prompt treatment.

• Parasites, Hosts and Diseases
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• v.61 no.4
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• pp.455-462
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• 2023

Since 2015, countries in the Sahel region have implemented large-scale seasonal malaria chemoprevention (SMC). However, the mass use of sulfadoxine-pyrimethamine (SP) plus amodiaquine impacts the genetic diversity of malaria parasites and their sensitivity to antimalarials. This study aimed to describe and compare the genetic diversity and SP resistance of Plasmodium falciparum strains in Mali and Niger. We collected 400 blood samples in Mali and Niger from children aged 3-59 months suspected of malaria. Of them, 201 tested positive (Niger, 111, 55.2%; Mali, 90, 44.8%). Polymorphism of merozoite surface protein 1 (msp1) genetic marker showed 201 allotypes. The frequency of the RO33 allotype was significantly higher in Niger (63.6%) than in Mali (39.3%). There was no significant difference in the frequency of the K1 and MAD20 allotypes between the 2 countries. The multiplicity of infection was 2 allotypes per patient in Mali and one allotype per patient in Niger. The prevalence of strains with the triple mutants Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H and Pfdhfr51I/Pfdhfr59R/Pfdhps437G was 18.1% and 30.2%, respectively, and 7.7% carried the quadruple mutant Pfdhfr51I/Pfdhfr59R/Pfdhps436A/F/H/Pfdhps437G. Despite the significant genetic diversity of parasite populations, the level of SP resistance was comparable between Mali and Niger. The frequency of mutations conferring resistance to SP still allows its effective use in intermittent preventive treatment in pregnant women and in SMC.

• 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.