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Research Interests:
Chikungunya virus (CHIKV) is an alphavirus transmitted to humans through the bite of infected Aedes mosquitoes. CHIKV causes fever and usually is not fatal, but can cause debilitating joint pains or, in rare instances, severe illness. The... more
Chikungunya virus (CHIKV) is an alphavirus transmitted to humans through the bite of infected Aedes mosquitoes. CHIKV causes fever and usually is not fatal, but can cause debilitating joint pains or, in rare instances, severe illness. The East/Central/South African strain of chikungunya has been emerging in Asia since 2006, first in the Indian subcontinent, then Thailand. This report describes the characteristics of a local outbreak linked with chikungunya reemergence in a rural Asian setting. Sporadic cases of chikungunya were identified in Cambodia in 2011. Antibodies to CHIKV have been detected in serum collected in Cambodia in 2007, but the strain could not be identified for those cases (U.S. Naval Medical Research Unit 2, unpublished data, 2012). On March 7, 2012, several cases of rash with fever were reported among village residents of Trapeang Roka in Kampong Speu Province, Cambodia. Subsequent field investigation revealed that four of six blood samples from affected persons ...
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Research Interests:
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Human infections with influenza A(H5N1) virus in Cambodia increased sharply during 2013. Molecular characterization of viruses detected in clinical specimens from human cases revealed the presence of mutations associated with the... more
Human infections with influenza A(H5N1) virus in Cambodia increased sharply during 2013. Molecular characterization of viruses detected in clinical specimens from human cases revealed the presence of mutations associated with the alteration of receptor-binding specificity (K189R, Q222L) and respiratory droplet transmission in ferrets (N220K with Q222L). Discovery of quasispecies at position 222 (Q/L), in addition to the absence of the mutations in poultry/environmental samples, suggested that the mutations occurred during human infection and did not transmit further.
Research Interests: Genetics, Technology, Plant Biology, Virology, Agricultural Biotechnology, and 18 moreMultidisciplinary, Biological Sciences, Seasonality, Discriminant Analysis, Crop Science, Genome, PLoS one, Clinical Sciences, PEST, Optometry and Ophthalmology, Molecular Marker, Phenotypic variation, Quantitative Trait Loci, Neurosciences, Interspecific hybrids, Genetic Linkage Map, QTL analysis, and Growing Season
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During the 2012 epidemic of dengue in Vientiane capital, Lao PDR, a major serotype switch from dengue 1 to 3 was observed. A molecular epidemiology study demonstrated that dengue 3 remained the predominant serotype in 2013, but also... more
During the 2012 epidemic of dengue in Vientiane capital, Lao PDR, a major serotype switch from dengue 1 to 3 was observed. A molecular epidemiology study demonstrated that dengue 3 remained the predominant serotype in 2013, but also revealed the co-circulation of two genotypes, supporting the hypothesis of multiple geographic origins of dengue 3 strains circulating in Vientiane capital.
Research Interests: Adolescent, Multidisciplinary, Dengue Virus, Molecular Epidemiology, LAOS, and 12 morePhylogeny, Humans, Child, Female, Male, Young Adult, Dengue, PLoS one, Aged, Middle Aged, Genotype, and Adult
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Research Interests: Computational Biology, Inflammation, Adolescent, Innate immunity, Multidisciplinary, and 18 moreMolecular Mechanics, Prospective studies, Humans, Child, Dengue fever, Female, Male, Polymerase Chain Reaction, Infant, Lipid metabolism, PLoS one, Inflammatory disease, Analysis of Variance, False discovery rate, Dengue Hemorrhagic Fever, Blood cells, Prospective Study, and Gene expression profiling
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Research Interests: Cambodia, Informed Consent, Adolescent, Urban Health, Dengue Virus, and 22 moreBiological Sciences, Rural Health, Seasonality, Humans, Child, Dengue fever, Female, Blood sampling, Male, Young Adult, Infant, Follow-up studies, Dengue, Incidence, Adult, Fever, Surveillance System, Preschool Children, Rural Area, Large Scale, Age Groups, and Urban Area
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Research Interests: Genetics, Polymorphism, Cambodia, Genetic Diversity, Phylogeny, and 13 moreHumans, Haplotypes, South east Asia, Scrub Typhus, Life Cycle, Linkage Disequilibrium, Genetic Recombination, Genetic variation, Orientia tsutsugamushi, Vertical Transmission, Mortality rate, DNA polymorphism, and Multilocus sequence typing
The Dengue National Control Program was established in Cambodia in 2000 and has reported between 10,000 and 40,000 dengue cases per year with a case fatality rate ranging from 0.7 to 1.7. In this study 39 DENV-2 and 57 DENV-3 viruses... more
The Dengue National Control Program was established in Cambodia in 2000 and has reported between 10,000 and 40,000 dengue cases per year with a case fatality rate ranging from 0.7 to 1.7. In this study 39 DENV-2 and 57 DENV-3 viruses isolated from patients between 2000 and 2008 were fully sequenced. Five DENV2 and four DENV3 distinct lineages with different dynamics were identified. Each lineage was characterized by the presence of specific mutations with no evidence of recombination. In both DENV-2 and DENV-3 the lineages present prior to 2003 were replaced after that date by unrelated lineages. After 2003, DENV-2 lineages D2-3 and D2-4 cocirculated until 2007 when they were almost completely replaced by a lineage D2-5 which emerged from D2-3 Conversely, all DENV-3 lineages remained, diversified and cocirculated with novel lineages emerging. Years 2006 and 2007 were marked by a high prevalence of DENV-3 and 2007 with a large dengue outbreak and a high proportion of patients with severe disease. Selective sweeps in DENV-1 and DENV-2 were linked to immunological escape to a predominately DENV-3-driven immunological response. The complex dynamic of dengue in Cambodia in the last ten years has been associated with a combination of stochastic climatic events, cocirculation, coevolution, adaptation to different vector populations, and with the human population immunological landscape.
Research Interests: Genetics, Cambodia, Climate, Adolescent, Dengue Virus, and 14 morePhylogeny, Disasters, Humans, Child, Mutation, Young Adult, Infant, Dengue, Aged, Middle Aged, Adult, Amino Acid Sequence, Base Sequence, and Serotyping
Research Interests: Genetics, Cambodia, Medical Microbiology, China, Vietnam, and 28 moreAdolescent, Rodentia, Genetic Diversity, Molecular Epidemiology, Ticks, Phylogeny, Humans, Child, Raw materials, Infectious Disease, Mice, Female, Animals, Scrub Typhus, Cluster Analysis, Young Adult, Infant, Phylogenetic analysis, Aged, Middle Aged, Spectrum, Adult, Public health systems and services research, Tick Infestations, Genetic variation, Orientia tsutsugamushi, Open Reading Frame, and Molecular Diagnosis
In Cambodia, dengue virus (DENV) was first isolated in 1963 and has become endemic with peak epidemic during raining season. Since 2000, the Dengue National Control Program has reported from 10,000 to 40,000 cases per year with fatality... more
In Cambodia, dengue virus (DENV) was first isolated in 1963 and has become endemic with peak epidemic during raining season. Since 2000, the Dengue National Control Program has reported from 10,000 to 40,000 cases per year with fatality rates ranging from 0.7 to 1.7. All four dengue serotypes are found circulating in Cambodia with alternative predominance of serotypes DENV-2 and DENV-3. The DENV-1 represents from 5% to 20% of all circulating viruses, depending upon the year. In this work, 79 clinical strains of DENV-1 were isolated between 2000 and 2009 and their genome fully sequenced. Four distinct lineages with different dynamics were identified. The main evolutionary drive was negative selective pressure but each lineage was characterized by the presence of specific mutations acquired through evolution. Coexistence, extinction and replacement of lineages occurred over the 10-year period. Lineages 1, 2 and 3 were all detected since 2000-2002 and disappeared in 2003, 2004-2005 and 2007, respectively. Lineages 1 and 2 displayed different dynamics. Lineage 1 was very diverse whereas lineage 2 was very homogeneous. Lineage 4 which derived from lineage 3 in 2003 remained the only one at the end of the sampling period in 2008-2009 owing to a selective sweep. The lineages dynamic of DENV-1 viruses and consequences for molecular epidemiology are discussed.