• Pediatric Infection and Vaccine
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• 제4권2호
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• pp.282-287
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• 1997

Malaria due to Plasmodium vivax had been known as an indigenous protozoan disease in Korea. However, massive use of insecticides and improvement of sanitation for several decades have led to rapid reduction of malaria incidence, then it was recognized to have been almost eradicated in recent years. However in 1993, one case was reported in Phajoo, Kyungki-do, and then, reported cases have been increasing annually. Recently we encountered one case of malaria in a 3 year old male child living in Dorim-dong, Seoul, who had never been abroad and had no history of transfusion, drug abuse, and travel to endemic area in Korea. He had characteristic fever, chill and splenomegaly and was confirmed as Plasmodium vivax malaria with peripheral blood smear finding. He was successfully treated with hydroxy chloroquine and primaquine. We report this case with brief review of related literature.

• Safety and Health at Work
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• 제10권1호
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• pp.122-124
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• 2019

Simian malaria is a zoonotic disease caused by Plasmodium knowlesi infection. The common natural reservoir of the parasite is the macaque monkey and the vector is the Anopheles mosquito. Human cases of P. knowlesi infection has been reported in all South East Asian countries in the last decade, and it is currently the most common type of malaria seen in Malaysia and Brunei. Between 2007-2017, 73 cases of P. knowlesi infection were notified and confirmed to the Ministry of Health in Brunei. Of these, 15 cases (21%) were documented as work-related, and 28 other cases (38%) were classified as probably related to work (due to incomplete history). The occupations of those with probable and confirmed work related infections were border patrol officers, Armed Forces and security personnel, Department of Forestry officers, boatmen and researchers. The remaining cases classified as most likely not related to work were possibly acquired via peri-domestic transmission. The risk of this zoonotic infection extends to tourists and overseas visitors who have to travel to the jungle in the course of their work. It can be minimised with the recommended use of prophylaxis for those going on duty into the jungles, application of mosquito/insect repellants, and use of repellant impregnated uniforms and bed nets in jungle camp sites.

• Parasites, Hosts and Diseases
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• 제60권2호
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• pp.109-116
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• 2022

Drug resistance is an important problem hindering malaria elimination in tropical areas. Point mutations in Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes confer resistance to antifolate drug, sulfadoxine-pyrimethamine (SP) while P. falciparum chloroquine-resistant transporter (Pfcrt) genes caused resistance to chloroquine (CQ). Decline in Pfdhfr/Pfdhps and Pfcrt mutations after withdrawal of SP and CQ has been reported. The aim of present study was to investigate the prevalence of Pfdhfr, Pfdhps, and Pfcrt mutation from 2 endemic areas of Thailand. All of 200 blood samples collected from western area (Thai-Myanmar) and southern area (Thai-Malaysian) contained multiple mutations in Pfdhfr and Pfdhps genes. The most prevalent haplotypes for Pfdhfr and Pfdhps were quadruple and double mutations, respectively. The quadruple and triple mutations of Pfdhfr and Pfdhps were common in western samples, whereas low frequency of triple and double mutations was found in southern samples, respectively. The Pfcrt 76T mutation was present in all samples examined. Malaria isolated from 2 different endemic regions of Thailand had high mutation rates in the Pfdhfr, Pfdhps, and Pfcrt genes. These findings highlighted the fixation of mutant alleles causing resistance of SP and CQ in this area. It is necessary to monitor the re-emergence of SP and CQ sensitive parasites in this area.

• Parasites, Hosts and Diseases
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• 제60권6호
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• pp.393-400
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• 2022

Human infection with simian malaria Plasmodium knowlesi is a cause for concern in Southeast Asian countries, especially in Malaysia. A previous study on Peninsular Malaysia P. knowlesi rhoptry associated protein-1 (PkRAP1) gene has discovered the existence of dimorphism. In this study, genetic analysis of PkRAP1 in a larger number of P. knowlesi samples from Malaysian Borneo was conducted. The PkRAP1 of these P. knowlesi isolates was PCR-amplified and sequenced. The newly obtained PkRAP1 gene sequences (n=34) were combined with those from the previous study (n=26) and analysed for polymorphism and natural selection. Sequence analysis revealed a higher genetic diversity of PkRAP1 compared to the previous study. Exon II of the gene had higher diversity (π=0.0172) than exon I (π=0.0128). The diversity of the total coding region (π=0.0167) was much higher than those of RAP1 orthologues such as PfRAP-1 (π=0.0041) and PvRAP1 (π=0.00088). Z-test results indicated that the gene was under purifying selection. Phylogenetic tree and haplotype network showed distinct clustering of Peninsular Malaysia and Malaysian Borneo PkRAP1 haplotypes. This geographical-based clustering of PkRAP1 haplotypes provides further evidence of the dimorphism of the gene and possible existence of 2 distinct P. knowlesi lineages in Malaysia.

• Parasites, Hosts and Diseases
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• 제61권1호
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• pp.78-83
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• 2023

The use of an effective antimalarial drug is the cornerstone of malaria control. However, the development and spread of resistant Plasmodium falciparum strains have placed the global eradication of malaria in serious jeopardy. Molecular marker analysis constitutes the hallmark of the monitoring of Plasmodium drug-resistance. This study included 96 P. falciparum PCR-positive samples from southern Somalia. The P. falciparum chloroquine resistance transporter gene had high frequencies of K76T, A220S, Q271E, N326S, and R371I point mutations. The N86Y and Y184F mutant alleles of the P. falciparum multidrug resistance 1 gene were present in 84.7 and 62.4% of the isolates, respectively. No mutation was found in the P. falciparum Kelch-13 gene. This study revealed that chloroquine resistance markers are present at high frequencies, while the parasite remains sensitive to artemisinin (ART). The continuous monitoring of ART-resistant markers and in vitro susceptibility testing are strongly recommended to track resistant strains in real time.

• Parasites, Hosts and Diseases
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• 제62권1호
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• pp.42-52
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• 2024

Antimalarial drugs are an urgently need and crucial tool in the campaign against malaria, which can threaten public health. In this study, we examined the cytotoxicity of the 9 antimalarial compounds chemically synthesized using SKM13-2HCl. Except for SKM13-2HCl, the 5 newly synthesized compounds had a 50% cytotoxic concentration (CC₅₀) >100 μM, indicating that they would be less cytotoxic than SKM13-2HCl. Among the 5 compounds, only SAM13-2HCl outperformed SKM13-2HCl for antimalarial activity, showing a 3- and 1.3-fold greater selective index (SI) (CC₅₀/IC₅₀) than SKM13-2HCl in vitro against both chloroquine-sensitive (3D7) and chloroquine -resistant (K1) Plasmodium falciparum strains, respectively. Thus, the presence of morpholine amide may help to effectively suppress human-infectious P. falciparum parasites. However, the antimalarial activity of SAM13-2HCl was inferior to that of the SKM13-2HCl template compound in the P. berghei NK65-infected mouse model, possibly because SAM13-2HCl had a lower polarity and less efficient pharmacokinetics than SKM13-2HCl. SAM13-2HCl was more toxic in the rodent model. Consequently, SAM13-2HCl containing morpholine was selected from screening a combination of pharmacologically significant structures as being the most effective in vitro against human-infectious P. falciparum but was less efficient in vivo in a P. berghei-infected animal model when compared with SKM13-2HCl. Therefore, SAM13-2HCl containing morpholine could be considered a promising compound to treat chloroquine-resistant P. falciparum infections, although further optimization is crucial to maintain antimalarial activity while reducing toxicity in animals.

• 한국미생물·생명공학회지
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• 제33권2호
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• pp.148-153
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• 2005

말라리아는 세계적으로 다시 발생하는 감염성 질환으로 모기에 의해 옮겨지는 말라리아 원충에 의해서 발병한다. 말라리아 원충을 검출하기 위하여 혈액 도말법 등 여러 가지 정량적인 assay가 활용 되고 있다. Real time PCR 은 반응이 일어나는 동안 PCR 산물의 생성을 계속적으로 모니터링 할 수 있는 방법으로서 최근 많은 환자들의 말라리아 원충을 한번에 탐지 하는데 적용되고 있다. 본 연구에서는 말라리아 원충 중 한국에서 질환을 일으키는 Plasmodium vivax를 탐지하기 위해 26명의 환자 혈액에서 분리 정제한 genomic DNA를 가지고 SYBR Green based-real time PCR을 수행하였다. 특히, 기존의 real time PCR에 사용한 18S rRNA와는 달리 DBP 유전자를 사용하여 새로운 말라리아 검출방법을 정량적이면서도 간편하고 경제적인 방법으로 개발하였다. 특히, real time PCR로 나온 결과를 임상적인 titer로 바꾸어 주기 위해서 reference 유전자로는 말라리아 환자의 상태와 관계없이 ACTB이 안정하다는 것을 real time PCR로 입증하였고 ACTB 유전자를 reference 유전자로 사용하였다. 본 연구에서는 real time PCR assay에 DBP라는 유전자를 처음 사용하였을 뿐 아니라 titer 보정을 위한 reference 유전자, ACTB를 real time PCR assay을 통해 확보하여 더 정확한 titer 값을 얻고자 했다. 이런 결과를 바탕으로 Taqman based-real time PCR과 본 연구의 결과를 정량비교를 하였다. 특히, 26명의 말라리아 환자 샘플을 3 group(Group I, II, III)로 나누어서 그 결과 정량적인 경향성 일치를 나타내었다. 특히, 높은 titer을 갖는 말라리아 샘플(Group I)에서 가장 많은 정량적인 차이를 보였지만, 간편하고 경제적인 SYBR Green-based real time PCR을 이용하여 DBP 유전자를 증폭하는 새로운 방법으로 말라리아를 Semi-quantitative 하게 검출할 수 있음을 보였다.

• 한국응용곤충학회:학술대회논문집
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• 한국응용곤충학회 2004년도 춘계 학술발표회
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• pp.33-33
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• 2004

• 한국응용곤충학회:학술대회논문집
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• 한국응용곤충학회 2002년도 추계 합동 특강 및 학술발표대회
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• pp.25-25
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• 2002

• Parasites, Hosts and Diseases
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• 제61권3호
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• pp.338-339
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• 2023