• Parasites, Hosts and Diseases
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• v.53 no.5
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• pp.575-581
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• 2015

Malaria is a tropical disease caused by protozoans of the Plasmodium genus. Delayed diagnosis and misdiagnosis are strongly associated with higher mortality. In recent years, a greater importance is attributed to Plasmodium knowlesi, a species found mainly in Southeast Asia. Routine parasitological diagnostics are associated with certain limitations and difficulties in unambiguous determination of the parasite species based only on microscopic image. Recently, molecular techniques have been increasingly used for predictive diagnosis. The aim of the study is to draw attention to the risk of travelling to knowlesi malaria endemic areas and to raise awareness among personnel involved in the therapeutic process.

• Parasites, Hosts and Diseases
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• v.60 no.6
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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.

• Safety and Health at Work
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• v.10 no.1
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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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• v.57 no.4
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• pp.445-450
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• 2019

Human infections due to the monkey malaria parasite Plasmodium knowlesi is increasingly being reported from most Southeast Asian countries specifically Malaysia. The parasite causes severe and fatal malaria thus there is a need for urgent measures for its control. In this study, the level of polymorphisms, haplotypes and natural selection of full-length pkmsp8 in 37 clinical samples from Malaysian Borneo along with 6 lab-adapted strains were investigated. Low levels of polymorphism were observed across the full-length gene, the double epidermal growth factor (EGF) domains were mostly conserved, and non-synonymous substitutions were absent. Evidence of strong negative selection pressure in the non-EGF regions were found indicating functional constrains acting at different domains. Phylogenetic haplotype network analysis identified shared haplotypes and indicated geographical clustering of samples originating from Peninsular Malaysia and Malaysian Borneo. This is the first study to genetically characterize the full-length msp8 gene from clinical isolates of P. knowlesi from Malaysia; however, further functional characterization would be useful for future rational vaccine design.

• Parasites, Hosts and Diseases
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• v.59 no.2
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• pp.113-119
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• 2021

The computer vision diagnostic approach currently generates several malaria diagnostic tools. It enhances the accessible and straightforward diagnostics that necessary for clinics and health centers in malaria-endemic areas. A new computer malaria diagnostics tool called the malaria scanner was used to investigate living malaria parasites with easy sample preparation, fast and user-friendly. The cultured Plasmodium parasites were used to confirm the sensitivity of this technique then compared to fluorescence-activated cell sorting (FACS) analysis and light microscopic examination. The measured percentage of parasitemia by the malaria scanner revealed higher precision than microscopy and was similar to FACS. The coefficients of variation of this technique were 1.2-6.7% for Plasmodium knowlesi and 0.3-4.8% for P. falciparum. It allowed determining parasitemia levels of 0.1% or higher, with coefficient of variation smaller than 10%. In terms of the precision range of parasitemia, both high and low ranges showed similar precision results. Pearson's correlation test was used to evaluate the correlation data coming from all methods. A strong correlation of measured parasitemia (r²=0.99, P<0.05) was observed between each method. The parasitemia analysis using this new diagnostic tool needs technical improvement, particularly in the differentiation of malaria species.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.187-188
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• 2016

열대열 말라리아(Plasmodium falciparum, P. falciparum, P. f) 신속진단키트의 경우, P. falciparum에 특이적인 단백질로써 Histidine Rich Protein 2 (PfHRP2)가 사용되고 있다. 그러나 최근 연구에서 남아메리카와 중앙아메리카를 중심으로 pfhrp2/pfhrp3 유전자가 결여된 P. falciparum 열원충이 나타나는 것으로 보고된 바 있다. 본 연구에서는 생물정보학을 기반으로 PfHRP2 항원 단백질을 대체할 수 있는 새로운 P. falciparum 특이 항원 단백질을 선정하고자, PlasmoDB에서 5,777개의 P. falciparum 관련 단백질 리스트를 얻었다. 이후 NCBI BLAST를 통해 단백질 아미노산 서열을 분석하고 정상인에게 존재하지 않으며, 동시에 다른 말라리아 열원충(P. vivax, P. ovale, P. malariae, P. knowlesi)에도 존재하지 않는 P. falciparum 특이 아미노산 서열을 가진 단백질 15개를 추출하였다. IEDB analysis를 이용하여 에피토프, 수용성, 베타-턴, 접근성, 유연성, 면역원성을 분석하여 높은 평균값을 갖는 상위 3개 단백질을 선별하였다. KEGG pathway와 EMBL-EBI를 통해 선별된 3개 단백질의 혈액내 검출 가능성 및 아미노산 서열의 보존성을 분석하여 최종적으로 Glutamate-Rich Protein (GLURP)을 선정하였다. AIDA를 통해 단백질 아미노산 서열을 이용한 3차 구조 예측으로 GLURP의 구조 및 항체와의 결합을 도식화하였다. 최종적으로 선정한 GLURP는 pfhrp2/pfhrp3 유전자 결여 P. falciparum까지 특이적으로 진단이 가능하여 차세대 P. falciparum 특이 신속진단키트 개발에 도움이 될 수 있을 것으로 기대한다.