Force Health Protection and Preventive Medicine

Seoul, South Korea

Force Health Protection and Preventive Medicine

Seoul, South Korea
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Takhampunya R.,U.S. Army | Kim H.-C.,5th Medical Detachment | Tippayachai B.,U.S. Army | Kengluecha A.,U.S. Army | And 4 more authors.
Virology Journal | Year: 2011

Background: Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of Culex tritaeniorhynchus and 1 pool of Cx. bitaeniorhynchus) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 2010. Findings. Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of Culex tritaeniorhynchus and one pool of Cx. bitaeniorhynchus were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from Cx. bitaeniorhynchus showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952. Conclusion: This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in Cx. bitaeniorhynchus, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies. © 2011 Takhampunya et al; licensee BioMed Central Ltd.

Suh S.J.,Kyungpook National University | Kim H.C.,5th Medical Detachment | Choi C.Y.,National Park Service | Nam H.Y.,National Park Service | And 3 more authors.
Journal of Medical Entomology | Year: 2012

One genus, Ornithoica Rondani, and two species, Ornithoica momiyamai Kishida, and O. unicolor Speiser, are reported for the first time from the Republic of Korea. A total of six species, including two new records, of louse flies were collected from 78 birds belonging to 35 species from Seoul and Incheon Metropolitan Areas and Gyeonggi, Gangwon, Gyeongsangbuk, Jeollabuk, and Jeollanam Provinces, 2005-2010. An updated checklist of Korean hippoboscids consisting of seven genera (Hippobosca L., Icosta Speiser, Lipoptena Nitzsch, Ornithoica Rondani, Ornithoctona Speiser, Ornithomya Lattreille, and Ornithophila Rondani) and 11 species is presented, including hosts, collection records, and repositories. © 2012 Entomological Society of America.

Kim H.C.,Fifth Medical Detachment | Chong S.T.,Fifth Medical Detachment | Chae J.-S.,Seoul National University | Lee H.,Seoul National University | And 2 more authors.
Journal of Medical Entomology | Year: 2010

This is the first confirmed record of the genus Lipoptena Nitzsch and its species, Lipoptena cervi (Linnaeus), from the Republic of Korea. A total of five females and 10 males was collected from eight of 29 Korean water deer, Hydropotes inermis argyropus Swinhoe, from Gangwon and Gyeongsangbuk Provinces and Ulsan Metropolitan Area from May through October 2008. An updated checklist of Korean hippoboscids contains nine species in six genera (Hippobosca Linnaeus, Icosta Speiser, Lipoptena, Ornithoctona. Speiser, Ornithomya Lattreille, and Ornithophila Rondani). Hosts, collection records, and repositories are also noted.

Seo H.-J.,Plant and Fisheries Quarantine and Inspection Agency | Kim H.C.,5th Medical Detachment | Klein T.A.,Force Health Protection and Preventive Medicine | Ramey A.M.,U.S. Geological Survey | And 7 more authors.
PLoS ONE | Year: 2013

Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen, is one of the major causes of viral encephalitis. To reduce the impact of Japanese encephalitis among children in the Republic of Korea (ROK), the government established a mandatory vaccination program in 1967. Through the efforts of this program only 0-7 (mean 2.1) cases of Japanese encephalitis were reported annually in the ROK during the period of 1984-2009. However, in 2010 there was an outbreak of 26 confirmed cases of Japanese encephalitis, including 7 deaths. This represented a >12-fold increase in the number of confirmed cases of Japanese encephalitis in the ROK as compared to the mean number reported over the last 26 years and a 3.7-fold increase over the highest annual number of cases during this same period (7 cases). Surveillance of adult mosquitoes was conducted during the 2010 outbreak of Japanese encephalitis in the ROK. A total of 6,328 culicine mosquitoes belonging to 12 species from 5 genera were collected at 6 survey sites from June through October 2010 and assayed by reverse-transcription polymerase chain reaction (RT-PCR) for the presence of JEV. A total of 34/371 pooled samples tested positive for JEV (29/121 Culex tritaeniorhynchus, 4/64 Cx. pipiens, and 1/26 Cx. bitaeniorhynchus) as confirmed by sequencing of the pre-membrane and envelope protein coding genes. The maximum likelihood estimates of JEV positive individuals per 1,000 culicine vectors for Cx. tritaeniorhynchus, Cx. pipiens, and Cx. bitaeniorhynchus were 11.8, 5.6, and 2.8, respectively. Sequences of the JEV pre-membrane and envelope protein coding genes amplified from the culicine mosquitoes by RT-PCR were compared with those of JEV genotypes I-V. Phylogenetic analyses support the detection of a single genotype (I) among samples collected from the ROK in 2010. © 2013 Seo et al.

Miller R.H.,Uniformed Services University of the Health Sciences | Masuoka P.,Uniformed Services University of the Health Sciences | Klein T.A.,Force Health Protection and Preventive Medicine | Kim H.-C.,168th Multifunctional Medical Battalion | And 2 more authors.
PLoS Neglected Tropical Diseases | Year: 2012

Background: Culex tritaeniorhynchus is the primary vector of Japanese encephalitis virus (JEV), a leading cause of encephalitis in Asia. JEV is transmitted in an enzootic cycle involving large wading birds as the reservoirs and swine as amplifying hosts. The development of a JEV vaccine reduced the number of JE cases in regions with comprehensive childhood vaccination programs, such as in Japan and the Republic of Korea. However, the lack of vaccine programs or insufficient coverage of populations in other endemic countries leaves many people susceptible to JEV. The aim of this study was to predict the distribution of Culex tritaeniorhynchus using ecological niche modeling. Methods/Principal Findings: An ecological niche model was constructed using the Maxent program to map the areas with suitable environmental conditions for the Cx. tritaeniorhynchus vector. Program input consisted of environmental data (temperature, elevation, rainfall) and known locations of vector presence resulting from an extensive literature search and records from MosquitoMap. The statistically significant Maxent model of the estimated probability of Cx. tritaeniorhynchus presence showed that the mean temperatures of the wettest quarter had the greatest impact on the model. Further, the majority of human Japanese encephalitis (JE) cases were located in regions with higher estimated probability of Cx. tritaeniorhynchus presence. Conclusions/Significance: Our ecological niche model of the estimated probability of Cx. tritaeniorhynchus presence provides a framework for better allocation of vector control resources, particularly in locations where JEV vaccinations are unavailable. Furthermore, this model provides estimates of vector probability that could improve vector surveillance programs and JE control efforts.

Seong K.M.,Seoul National University | Lee D.-Y.,Amherst Regional High School | Yoon K.S.,University of Massachusetts Amherst | Kwon D.H.,Seoul National University | And 4 more authors.
Journal of Medical Entomology | Year: 2010

Two point mutations (V419L and L925I) in the voltage-sensitive sodium channel -subunit gene have been identified in deltamethrin-resistant bed bugs. A quantitative sequencing (QS) protocol was developed to establish a population-based genotyping method as a molecular resistance-monitoring tool based on the frequency of the two mutations. The nucleotide signal ratio at each mutation site was generated from sequencing chromatograms and plotted against the corresponding resistance allele frequency. Frequency prediction equations were generated from the plots by linear regression, and the signal ratios were shown to highly correlate with resistance allele frequencies (r2 > 0.9928). As determined by QS, neither mutation was found in a bed bug population collected in 1993. Populations collected in recent years (20072009), however, exhibited completely or nearly saturating L925I mutation frequencies and highly variable frequencies of the V419L mutation. In addition to QS, the filter contact vial bioassay (FCVB) method was established and used to determine the baseline susceptibility and resistance of bed bugs to deltamethrin and -cyhalothrin. A pyrethroid-resistant strain showed >9,375- and 6,990-fold resistance to deltamethrin and -cyhalothrin, respectively. Resistance allele frequencies in different bed bug populations predicted by QS correlated well with the FCVB results, confirming the roles of the two mutations in pyrethroid resistance. Taken together, employment of QS in conjunction with FCVB should greatly facilitate the detection and monitoring of pyrethroid-resistant bed bugs in the field. The advantages of FCVB as an on-site resistance-monitoring tool are discussed. © 2010 Entomological Society of America.

Kim H.C.,Medical Detachment 5th | Lee I.Y.,Yonsei University | Chong S.T.,Medical Detachment 5th | Richards A.L.,Naval Medical Research Center | And 4 more authors.
Korean Journal of Parasitology | Year: 2010

Comprehensive quarterly serosurveillance on scrub typhus in small mammals collected from military training sites located near the Demilitarized Zone (DMZ), northern Gyeonggi-do (Province), ROK was conducted to determine the potential rodent-borne and associated ectoparasite disease risks to military personnel. A total of 1,196 rodents and insec- tivores representing 8 species, Apodemus agrarius (87.3%, n = 1,044), Mus musculus (5.4%, n = 65), Crocidura lasiura (3.3%, n = 40), Microtus fortis (2.6%, n = 31), Micromys minutus (0.3%, n = 4), Tscherskia triton (0.3%, n = 4), Rattus norvegicus (0.3%, n = 4), and Myodes regulus (0.3%, n = 4) were assayed for the presence of antibodies to Orientia tsut- sugamushi. O. tsutsugamushi antibodies were detected in 6 of 8 species and seroprevalence determined; A. agrarius (45.6%), M. musculus (23.1%), M. fortis (48.4%), M. minutus (50.0%), T. triton (50.0%), and R. norvegicus (25.0%). A total of 31,184 chigger mites collected from 508 rodents and insectivores were slide-mounted and 10 species belonging to 4 genera were identified. Leptotrombidium pallidum (53.4%) was the most frequently collected, followed by L. palpale (15.7%), Neotrombicula tamiyai (14.3%), L. orientale (10.7%), L. zetum (3.1%), Walchia fragilis (2.1%), and L. gemiticu- lum (0.8%), while the remaining 3 species, L. subintermedium, N. gardellai, and Euschoengastia koreaensis were rarely observed (prevalence < 10%). In contrast to previous surveys, higher chigger indices of the primary scrub typhus vectors, L. pallidum (165.4), L. orientale (45.0), and L. palpale (21.4), were observed during the spring season.

Foley D.H.,U.S. Army | Klein T.A.,Force Health Protection and Preventive Medicine | Kim H.C.,168th Multifunctional Medical Battalion | Brown T.,U.S. Army | And 2 more authors.
Journal of the American Mosquito Control Association | Year: 2010

Data on molecularly identified adult and larval mosquitoes collected from 104 sites from the Republic of Korea (ROK) in 2007 were used to test the predictive ability of recently reported ecological niche models (ENMs) for 8 potential malaria vectors. The ENMs, based on the program Maxent and the least presence threshold criterion, predicted 100 of new collection locations for Anopheles sinensis, An. belenrae, An. pullus, and An. sineroides; 96 of locations for An. kleini; and 83 for An. lesteri, but were relatively unsuccessful for the infrequently collected non-Hyrcanus group species An. koreicus and An. lindesayi japonicas. The ENMs produced with the use of Maxent had fewer omission errors than those using the Genetic Algorithm for Rule-Set Prediction program. The results emphasize the importance of independent test data for validation and improvement of ENMs, and lend support for the further development of ENMs for predicting the distribution of malaria vectors in the ROK. © 2010 by The American Mosquito Control Association, Inc.

Rueda L.M.,U.S. Army | Rueda L.M.,Smithsonian Institution | Li C.,U.S. Army | Kim H.C.,5th Medical Detachment | And 3 more authors.
Journal of the American Mosquito Control Association | Year: 2010

The malarial parasite, Plasmodium vivax, was detected in 4 species of Anopheles (Hyrcanus Group) mosquitoes, namely An. kleini, An. pullus, An. belenrae, and An. sinensis, from Gyeonggi Province, Republic of Korea (ROK). This study confirmed that An. belenrae was infected by P. vivax, and implicated this species as a potential vector of vivax malaria in the ROK. © 2010 by The American Mosquito Control Association, Inc.

Richards E.E.,Bethesda University | Masuoka P.,Bethesda University | Brett-Major D.,Bethesda University | Brett-Major D.,U.S. Navy | And 5 more authors.
International Journal of Health Geographics | Year: 2010

Background: Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is endemic to the Republic of Korea (ROK) where unvaccinated United States (U.S.) military Service members, civilians and family members are stationed. The primary vector of the JEV in the ROK is Culex tritaeniorhynchus. The ecological relationship between Culex spp. and rice fields has been studied extensively; rice fields have been shown to increase the prevalence of Cx. tritaeniorhynchus. This research was conducted to determine if the quantification of rice field land cover surrounding U.S. military installations in the ROK should be used as a parameter in a larger risk model that predicts the abundance of Cx. tritaeniorhynchus populations.Mosquito data from the U.S. Forces Korea (USFK) mosquito surveillance program were used in this project. The average number of female Cx. tritaeniorhynchus collected per trap night for the months of August and September, 2002-2008, was calculated. Rice fields were manually digitized inside 1.5 km buffer zones surrounding U.S. military installations on high-resolution satellite images, and the proportion of rice fields was calculated for each buffer zone.Results: Mosquito data collected from seventeen sample sites were analyzed for an association with the proportion of rice field land cover. Results demonstrated that the linear relationship between the proportion of rice fields and mosquito abundance was statistically significant (R2= 0.62, r = .79, F = 22.72, p < 0.001).Conclusions: The analysis presented shows a statistically significant linear relationship between the two parameters, proportion of rice field land cover and log10of the average number of Cx. tritaeniorhynchus collected per trap night. The findings confirm that agricultural land cover should be included in future studies to develop JE risk prediction models for non-indigenous personnel living at military installations in the ROK. © 2010 Richards et al; licensee BioMed Central Ltd.

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