| Hyeong-Woo Lee | 13 Articles |
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 make-up 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 expo- nentially. However, continued surveillance is needed to prevent future resurgence.
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Echinostoma cinetorchis is an oriental intestinal fluke causing significant pathological damage to the small intestine. The aim of this study was to determine a full-length cDNA sequence of E. cinetorchis endoribonuclease (RNase H; EcRNH) and to elucidate its molecular biological characters. EcRNH consisted of 308 amino acids and showed low similarity to endoribonucleases of other parasites (<40%). EcRNH had an active site centered on a putative DDEED motif instead of DEDD conserved in other species. A recombinant EcRNH produced as a soluble form in Escherichia coli showed enzymatic activity to cleave the 3'-O-P bond of RNA in a DNA-RNA duplex, producing 3'-hydroxyl and 5'-phosphate. These findings may contribute to develop antisense oligonucleotides which could damage echinostomes and other flukes.
During civil engineering construction near Sejong-ro, Jongro-ku, Seoul, cultural sites were found that are thought to have been built in the 15th century. This area was home to many different people as well as the leaders of the Yi dynasty. To gain further insight into the life styles of the inhabitants of the old capital, soil samples were collected from various areas such as toilets, water foundations, and drainage ways. Parasite eggs were examined by microscopy after 5 g soil samples were rehydrated in 0.5% trisodium phosphate solution. A total of 662 parasite eggs from 7 species were found. Species with the highest number of eggs found were Ascaris lumbricoides (n=483), followed by Trichuris trichiura (138), Trichuris vulpis (21), Fasciola hepatica (8), Clonorchis sinensis (6), Paragonimus westermani (4), and Metagonimus yokogawai (2). These findings indirectly indicate the food habits of the people in Yi dynasty.
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The relationship between anti-Plasmodium vivax circumsporozoite protein (CSP) antibody levels and the prevalence of malaria in epidemic areas of South Korea was evaluated. Blood samples were collected from inhabitants of Gimpo-si (city), Paju-si, and Yeoncheon-gun (county) in Gyeonggi-do (province), as well as Cheorwon-gun in Gangwon-do from November to December 2004. Microscopic examinations were used to identify malaria parasites. ELISA was used to quantitate anti-circumsporozoite protein (CSP) antibodies against P. vivax. A total of 1,774 blood samples were collected. The overall CSP-ELISA-positive rate was 7.7% (n=139). The annual parasite incidences (APIs) in these areas gradually decreased from 2004 to 2005 (1.09 and 0.80, respectively). The positive rate in Gimpo (10.4%, 44/425) was the highest identified by CSP-ELISA. The highest API was found in Yeoncheon, followed by Cheorwon, Paju, and Gimpo in both years. The positive rates of CSP-ELISA were closely related to the APIs in the study areas. These results suggest that seroepidemiological studies based on CSP may be helpful in estimating the malaria prevalence in certain areas. In addition, this assay can be used to establish and evaluate malaria control and eradication programs in affected areas.
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A family of calcium-dependent protein kinases (CDPKs) is a unique enzyme which plays crucial roles in intracellular calcium signaling in plants, algae, and protozoa. CDPKs of malaria parasites are known to be key regulators for stage-specific cellular responses to calcium, a widespread secondary messenger that controls the progression of the parasite. In our study, we identified a gene encoding Citations Citations to this article as recorded by
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In order to develop tools for an early serodiagnosis of Citations Citations to this article as recorded by
The plasmepsins are the aspartic proteases of malaria parasites. Treatment of aspartic protease inhibitor inhibits hemoglobin hydrolysis and blocks the parasite development in vitro suggesting that these proteases might be exploited their potentials as antimalarial drug targets. In this study, we determined the genetic variations of the aspartic proteases of Citations Citations to this article as recorded by
In order to study the range of flight and feeding activity of Citations Citations to this article as recorded by
Attempts were made to isolate and identify Korean bovine Citations Citations to this article as recorded by
Three anopheline mosquitoes in Korea were studied for their abilities as vectors for Citations Citations to this article as recorded by
A result of national malaria surveillance in Korean civilians was described. Since a case of indigenous vivax malaria was detected in 1993, a total of 2,198 cases was confirmed by blood smear up to 1997. Of them, 1,548 cases were soldiers serving in the demilitarized zone (DMZ), while 650 cases were civilians. Number of civilian cases was 3 in 1994, 19 in 1995, 71 in 1996, and 557 in 1997. Of them, 239 were ex-soldiers who discharged after military service in the prevalent areas such as Paju, Yonchon, Kimpo, Kangwha, Tongduchon in Kyonggi-do and Chorwon in Kangwon-do while 308 patients were civilian residents in the prevalent areas. Seventy-two patients, living nationwide, had a history of visiting the prevalent areas during transmission season. Only 32 civilian patients denied any relation with the prevalent areas. As a whole, a half of the civilian cases was diagnosed when living in non-prevalent areas. Male patients in their twenties was the highest in number. Annual parasite index is steadily elevated in residents living in the prevalent areas. Monthly incidence showed an unimodal distribution, forming a peak in August. Ex-soldiers exhibited a delayed incubation ranging from 153 to 452 days (279 ± 41 days). The time required for diagnosis was shortened from 23.6 days in 1995 to 13.7 days in 1997. Although the current epidemic of vivax malaria started as a border malaria, it seems highly probable that vivax malaria is established in the local areas and responsible for at least a part of transmission. Citations Citations to this article as recorded by
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