Displaying publications 1 - 20 of 58 in total

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  1. [Is the fight against dengue complicated with the emergence of a new viral serotype?]
    Valero N, Quiroz Y
    Invest Clin, 2014 Sep;55(3):203-5.
    PMID: 25272519
    Dengue is a viral acute febrile illness, currently considered one of the most important arbovirosis worldwide in terms of morbidity, mortality and economic impact. Various theories have been proposed to explain the pathogenesis of severe forms of dengue, involving among other factors, features related to the virus, such as the presence of more virulent strains and/or strains with increased replicative capacity. A crucial point at this time is the discovery of a new viral type, dengue 5, from nonhuman primates in Malaysia-Borneo, which could result in greater difficulties for control and vaccine production (currently in efficacy tests). Once the circulation of this viral type has been demonstrated in the human population, the high risk of infection will have extreme or controversial public health implications. Therefore, a worldwide program to combat dengue should include an urgent need to implement continuous vector elimination, community education and prevention and control of the disease. Only then, we will be aiming to reduce the morbidity and transmission risk of dengue, while new technological and effective alternatives come about.
    Matched MeSH terms: Dengue Virus/classification*
  2. Fulltext Trends of dengue infections in Malaysia, 2000-2010
    Mia MS, Begum RA, Er AC, Abidin RD, Pereira JJ
    Asian Pac J Trop Med, 2013 Jun;6(6):462-6.
    PMID: 23711707 DOI: 10.1016/S1995-7645(13)60075-9
    OBJECTIVE: To analyze trends of dengue incidences and deaths in Malaysia from 2000 to 2010 as well as the predominant dengue virus serotypes during the last decade.

    METHODS: We used the national data on annual reported cases, deaths, incidence rate, mortality rate, and case fatality rate of dengue fever (DF) and dengue hemorrhagic fever (DHF) as well as dengue virus serotypes prevalent in Malaysia during the last decade. Trend/ regression lines were fitted to investigate the trend of dengue incidences and deaths due to the disease for a 11-year period (2000-2010). For the distribution of national incidence rate, mortality rate, and case fatality rate of DF and DHF, descriptive statistics using mean and 95% confidence intervals (CI 39) for means, and range were applied.

    RESULTS: The number of dengue cases and number of deaths have increased, on average, by 14% and 8% per year respectively. The average annual incidence rate of DF per 100 000 populations was higher as compared to that of DHF. Conversely, the yearly mean mortality rate of DHF per 100 000 populations was greater than that of DF. The simultaneous circulation of all four dengue serotypes has been found in Malaysia. But a particular dengue virus serotype predominates for at least two years before it becomes replaced by another serotype.

    CONCLUSIONS: The dengue situation in Malaysia has worsened with an increasing number of reported cases and deaths during the last decade. The increasing trend of dengue highlights the need for a more systematic surveillance and reporting of the disease.

    Matched MeSH terms: Dengue Virus/classification
  3. Micro-anatomical changes in major blood vessel caused by dengue virus (serotype 2) infection
    Priya SP, Sakinah S, Ling MP, Chee HY, Higuchi A, Hamat RA, et al.
    Acta Trop, 2017 Jul;171:213-219.
    PMID: 28427958 DOI: 10.1016/j.actatropica.2017.04.010
    Dengue virus (DENV) has emerged as a major economic concern in developing countries, with 2.5 billion people believed to be at risk. Vascular endothelial cells (ECs) lining the circulatory system from heart to end vessels perform crucial functions in the human body, by aiding gas exchange in lungs, gaseous, nutritional and its waste exchange in all tissues, including the blood brain barrier, filtration of fluid in the glomeruli, neutrophil recruitment, hormone trafficking, as well as maintenance of blood vessel tone and hemostasis. These functions can be deregulated during DENV infection. In this study, BALB/c mice infected with DENV serotype 2 were analyzed histologically for changes in major blood vessels in response to DENV infection. In the uninfected mouse model, blood vessels showed normal architecture with intact endothelial monolayer, tunica media, and tunica adventitia. In the infected mouse model, DENV distorted the endothelium lining and disturbed the smooth muscle, elastic laminae and their supporting tissues causing vascular structural disarrangement. This may explain the severe pathological illness in DENV-infected individuals. The overall DENV-induced damages on the endothelial and it's supporting tissues and the dysregulated immune reactions initiated by the host were discussed.
    Matched MeSH terms: Dengue Virus/classification*
  4. Fulltext Subversion of immunoproteasome subunit expression in dengue virus serotype 2-infected HepG2 cells
    Gan CS, Lim PJ, Razif MF, Yusof R, Othman S
    Rev Soc Bras Med Trop, 2017 Jan-Feb;50(1):99-103.
    PMID: 28327809 DOI: 10.1590/0037-8682-0207-2016
    INTRODUCTION:: Infection with all serotypes of dengue virus (DV) results in augmented antigen presentation by MHC class I molecules. However, the upregulation of immunoproteasome subunits only results from infection with two serotypes. This study aims to elucidate changes in the expression of immunoproteasome subunits resulting from infection with DV, particularly DV serotype 2 (DV2).

    METHODS:: HepG2 cells were grown in various culture milieu. Total cellular RNA and proteins were extracted and quantified.

    RESULTS:: Results demonstrated sequestration of immunoproteasome subunits LMP2 and LMP7 in DV2-infected cells.

    CONCLUSIONS:: This study provides insights into the mechanisms underlying immune evasion by DV.
    Matched MeSH terms: Dengue Virus/classification
  5. Fulltext Isolation of ancestral sylvatic dengue virus type 1, Malaysia
    Teoh BT, Sam SS, Abd-Jamil J, AbuBakar S
    Emerg Infect Dis, 2010 Nov;16(11):1783-5.
    PMID: 21029545 DOI: 10.3201/eid1611.100721
    Ancestral sylvatic dengue virus type 1, which was isolated from a monkey in 1972, was isolated from a patient with dengue fever in Malaysia. The virus is neutralized by serum of patients with endemic DENV-1 infection. Rare isolation of this virus suggests a limited spillover infection from an otherwise restricted sylvatic cycle.
    Matched MeSH terms: Dengue Virus/classification*
  6. Fulltext Sylvatic dengue virus type 4 in Aedes aegypti and Aedes albopictus mosquitoes in an urban setting in Peninsular Malaysia
    Johari NA, Voon K, Toh SY, Sulaiman LH, Yap IKS, Lim PKC
    PLoS Negl Trop Dis, 2019 Nov;13(11):e0007889.
    PMID: 31730672 DOI: 10.1371/journal.pntd.0007889
    Dengue fever is endemic in Malaysia, contributing to significant economic and health burden in the country. Aedes aegypti and Ae. albopictus are the main vectors of the dengue virus (DENV), which circulates in sylvatic and human transmission cycles and has been present in Malaysia for decades. The study investigated the presence and distribution of DENV in urban localities in the Klang Valley, Peninsular Malaysia. A total of 364 Ae. aegypti and 1,025 Ae. albopictus larvae, and 10 Ae. aegypti and 42 Ae. albopictus adult mosquitoes were screened for the presence of DENV. In total, 31 (2.2%) samples were positive, of which 2 Ae. albopictus larvae were co-infected with two serotypes, one with DENV-2 and DENV-3 and the other with DENV-3 and DENV-4. Phylogenetic analysis determined that the isolates belonged to DENV-1 genotype I (1 Ae. aegypti adult), DENV-2 (1 Ae. albopictus larva), DENV-3 genotype V (3 Ae. aegypti larvae and 10 Ae. albopictus larvae) and DENV-4 genotype IV (6 Ae. aegypti larvae and 12 Ae. albopictus larvae), a sylvatic strain of DENV-4 which was most closely related with sylvatic strains isolated from arboreal mosquitoes and sentinel monkeys in Peninsular Malaysia in the 1970s. All four DENV serotypes were co-circulating throughout the study period. The detection of a sylvatic strain of DENV-4 in Ae. aegypti and Ae. albopictus mosquitoes in urban areas in Peninsular Malaysia highlights the susceptibility of these vectors to infection with sylvatic DENV. The infectivity and vector competence of these urban mosquitoes to this strain of the virus needs further investigation, as well as the possibility of the emergence of sylvatic virus into the human transmission cycle.
    Matched MeSH terms: Dengue Virus/classification
  7. Fulltext Epidemiology of dengue disease in Malaysia (2000-2012): a systematic literature review
    Mohd-Zaki AH, Brett J, Ismail E, L'Azou M
    PLoS Negl Trop Dis, 2014;8(11):e3159.
    PMID: 25375211 DOI: 10.1371/journal.pntd.0003159
    A literature survey and analysis was conducted to describe the epidemiology of dengue disease in Malaysia between 2000 and 2012. Published literature was searched for epidemiological studies of dengue disease, using specific search strategies for each electronic database; 237 relevant data sources were identified, 28 of which fulfilled the inclusion criteria. The epidemiology of dengue disease in Malaysia was characterized by a non-linear increase in the number of reported cases from 7,103 in 2000 to 46,171 in 2010, and a shift in the age range predominance from children toward adults. The overall increase in dengue disease was accompanied by a rise in the number, but not the proportion, of severe cases. The dominant circulating dengue virus serotypes changed continually over the decade and differed between states. Several gaps in epidemiological knowledge were identified; in particular, studies of regional differences, age-stratified seroprevalence, and hospital admissions.

    PROTOCOL REGISTRATION: PROSPERO #CRD42012002293.

    Matched MeSH terms: Dengue Virus/classification*
  8. [A possible fifth dengue virus serotype]
    da Silva Voorham JM
    Ned Tijdschr Geneeskd, 2014;158:A7946.
    PMID: 25227888
    Sylvatic dengue viruses are both evolutionarily and ecologically distinguishable from the human dengue virus (DENV). Sporadic episodes of sylvatic human infections in West Africa and Southeast Asia suggest that sylvatic DENV regularly come into contact with human beings. Following a study on the sylvatic transmission cycle in Malaysia in 2007, researchers announced that a new DENV serotype, DENV-5, had been discovered. Scientists are still sceptical about these new findings, and indicate that more data is necessary to determine whether this 'new' virus really is a different serotype or whether it is a variant of one of the four DENV serotypes already known. The good news is that this new variant has not yet established itself in the human transmission cycle. However, if it really is a new serotype this will have implications for the long-term control of dengue using vaccines currently under development.
    Matched MeSH terms: Dengue Virus/classification*
  9. Phylogenetic analysis of dengue virus types 1 and 3 isolated in Jakarta, Indonesia in 1988
    Sjatha F, Takizawa Y, Yamanaka A, Konishi E
    Infect Genet Evol, 2012 Dec;12(8):1938-43.
    PMID: 22959957 DOI: 10.1016/j.meegid.2012.08.006
    Dengue viruses are mosquito-borne viruses that cause dengue fever and dengue hemorrhagic fever, both of which are globally important diseases. These viruses have evolved in a transmission cycle between human hosts and mosquito vectors in various tropical and subtropical environments. We previously isolated three strains of dengue type 1 virus (DENV1) and 14 strains of dengue type 3 virus (DENV3) during an outbreak of dengue fever and dengue hemorrhagic fever in Jakarta, Indonesia in 1988. Here, we compared the nucleotide sequences of the entire envelope protein-coding region among these strains. The isolates were 97.6-100% identical for DENV1 and 98.8-100% identical for DENV3. All DENV1 isolates were included in two different clades of genotype IV and all DENV3 isolates were included in a single clade of genotype I. For DENV1, three Yap Island strains isolated in 2004 were the only strains closely related to the present isolates; the recently circulated Indonesian strains were in different clades. Molecular clock analyses estimated that ancestors of the genotype IV strains of DENV1 have been indigenous in Indonesia since 1948. We predict that they diverged frequently around 1967 and that their offspring distributed to Southeast Asia, the Western Pacific, and Africa. For DENV3, the clade containing all the present isolates also contained strains isolated from other Indonesian regions and other countries including Malaysia, Singapore, China, and East Timor from 1985-2010. Molecular clock analyses estimated that the common ancestor of the genotype I strains of DENV3 emerged in Indonesia around 1967 and diverged frequently until 1980, and that their offspring distributed mainly in Southeast Asia. The first dengue outbreak in 1968 and subsequent outbreaks in Indonesia might have influenced the divergence and distribution of the DENV1 genotype IV strains and the DENV3 genotype I strains in many countries.
    Matched MeSH terms: Dengue Virus/classification*
  10. Evolutionary history of Dengue virus type 4: insights into genotype phylodynamics
    Villabona-Arenas CJ, Zanotto PM
    Infect Genet Evol, 2011 Jul;11(5):878-85.
    PMID: 21335103 DOI: 10.1016/j.meegid.2011.02.007
    Dengue virus type 4 (DENV-4) circulates in tropical and subtropical countries from Asia and the Americas. Despite the importance of dengue virus distribution, little is known about the worldwide viral spread. Following a Bayesian phylogenetic approach we inferred the evolutionary history of 310 isolates sampled from 37 countries during the time period 1956-2008 and the spreading dynamics for genotypes I and II. The region (tropical rainforest biome) comprised by Malaysia-Thailand was the most likely ancestral area from which the serotype has originated and spread. Interestingly, cross-correlation analysis on demographic time series with the Asian sequences showed a statistically significant negative correlation that could be suggestive of competition among genotypes within the same serotype.
    Matched MeSH terms: Dengue Virus/classification*
  11. Molecular typing of dengue viruses circulating on the East Coast of Peninsular Malaysia from 2005 to 2009
    Vinomarlini G, Rogayah T, Saraswathy TS, Thayan R, Apandi M, Fauziah MK, et al.
    Southeast Asian J. Trop. Med. Public Health, 2011 Jan;42(1):94-9.
    PMID: 21323170
    From 2005 to 2009, the Institute for Medical Research (IMR), Kuala Lumpur, Malaysia received 488 serum and blood samples from hospitalized patients on the East Coast of Peninsular Malaysia, suspected of having dengue infection. In this study we determined the prevailing dengue serotypes using a real time polymerase chain reaction assay (RT-PCR). All 4 dengue virus serotypes were found circulating during the study period; however the predominant serotype varied. In 2005 and 2006, the predominant serotypes circulating were DENV-1 and DENV-3, in 2007, DENV-1 and DENV-2 were predominant, and in 2008 and 2009, DENV-3 was the predominant serotype.
    Matched MeSH terms: Dengue Virus/classification*
  12. [Identification and sequence analysis of E gene of Dengue virus type 2 strain isolated from patient serum in Shenzhen]
    Yang F, He JF, Xian HX, Zhang HL, He YQ, Yang H, et al.
    Zhonghua Yu Fang Yi Xue Za Zhi, 2009 Sep;43(9):798-802.
    PMID: 20137564
    To isolate and identify the pathogen of Dengue fever from Shenzhen city in 2005 - 2006, and to analyze the molecular characteristics of the isolated Dengue virus strain as well as to explore its possible origin.
    Matched MeSH terms: Dengue Virus/classification
  13. Outlook of dengue in Malaysia: a century later
    Abubakar S, Shafee N
    Malays J Pathol, 2002 Jun;24(1):23-7.
    PMID: 16329552
    Dengue continues to be a major health threat to Malaysia a century after its first reported outbreak in 1902. Examination of the available outbreak data suggested that a major DF/DHF outbreak occurred in Malaysia in a cyclical pattern of approximately every 8 years. All four dengue virus serotypes are found co-circulating in Malaysia, but after the first and only major outbreak involving DEN-4 in 1960's, only DEN-1, DEN-2 and DEN-3 were associated with DF/DHF outbreaks. It is argued that perhaps the spread of the later dengue virus serotypes followed the pattern of spread of the mosquito vector Aedes aegypti, whereas the former was associated with Aedes albopictus, the outdoor and rural area dwelling mosquito. Estimating from the trend and pattern of dengue and the associated dengue virus serotypes, unless there is a major breakthrough in dengue vaccine development, it is likely that dengue outbreaks will continue to occur in Malaysia throughout the 21st century.
    Matched MeSH terms: Dengue Virus/classification
  14. Divergence of the dengue virus type 2 Cosmopolitan genotype associated with two predominant serotype shifts between 1 and 2 in Surabaya, Indonesia, 2008-2014
    Kotaki T, Yamanaka A, Mulyatno KC, Churrotin S, Sucipto TH, Labiqah A, et al.
    Infect Genet Evol, 2016 Jan;37:88-93.
    PMID: 26553170 DOI: 10.1016/j.meegid.2015.11.002
    Indonesia is one of the biggest dengue endemic countries, and, thus, is an important place to investigate the evolution of dengue virus (DENV). We have continuously isolated DENV in Surabaya, the second biggest city in Indonesia, since 2008. We previously reported sequential changes in the predominant serotype from DENV type 2 (DENV-2) to DENV type 1 (DENV-1) in November 2008 and from DENV-1 to DENV-2 in July 2013. The predominance of DENV-2 continued in 2014, but not in 2015. We herein phylogenetically investigated DENV-2 transitions in Surabaya between 2008 and 2014 to analyze the divergence and evolution of DENV-2 concomitant with serotype shifts. All DENV-2 isolated in Surabaya were classified into the Cosmopolitan genotype, and further divided into 6 clusters. Clusters 1-3, dominated by Surabaya strains, were defined as the "Surabaya lineage". Clusters 4-6, dominated by strains from Singapore, Malaysia, and many parts of Indonesia, were the "South East Asian lineage". The most recent common ancestor of these strains existed in 1988, coinciding with the time that an Indonesian dengue outbreak took place. Cluster 1 appeared to be unique because no other DENV-2 isolate was included in this cluster. The predominance of DENV-2 in 2008 and 2013-14 were caused by cluster 1, whereas clusters 2 and 3 sporadically emerged in 2011 and 2012. The characteristic amino acids of cluster 1, E-170V and E-282Y, may be responsible for its prevalence in Surabaya. No amino acid difference was observed in the envelope region between strains in 2008 and 2013-14, suggesting that the re-emergence of DENV-2 in Surabaya was due to the loss or decrease of herd immunity in the 5-year period when DENV-2 subsided. The South East Asian lineage primarily emerged in Surabaya in 2014, probably imported from other parts of Indonesia or foreign countries.
    Matched MeSH terms: Dengue Virus/classification*
  15. Fulltext The Role of Serotype Interactions and Seasonality in Dengue Model Selection and Control: Insights from a Pattern Matching Approach
    Ten Bosch QA, Singh BK, Hassan MR, Chadee DD, Michael E
    PLoS Negl Trop Dis, 2016 05;10(5):e0004680.
    PMID: 27159023 DOI: 10.1371/journal.pntd.0004680
    The epidemiology of dengue fever is characterized by highly seasonal, multi-annual fluctuations, and the irregular circulation of its four serotypes. It is believed that this behaviour arises from the interplay between environmental drivers and serotype interactions. The exact mechanism, however, is uncertain. Constraining mathematical models to patterns characteristic to dengue epidemiology offers a means for detecting such mechanisms. Here, we used a pattern-oriented modelling (POM) strategy to fit and assess a range of dengue models, driven by combinations of temporary cross protective-immunity, cross-enhancement, and seasonal forcing, on their ability to capture the main characteristics of dengue dynamics. We show that all proposed models reproduce the observed dengue patterns across some part of the parameter space. Which model best supports the dengue dynamics is determined by the level of seasonal forcing. Further, when tertiary and quaternary infections are allowed, the inclusion of temporary cross-immunity alone is strongly supported, but the addition of cross-enhancement markedly reduces the parameter range at which dengue dynamics are produced, irrespective of the strength of seasonal forcing. The implication of these structural uncertainties on predicted vulnerability to control is also discussed. With ever expanding spread of dengue, greater understanding of dengue dynamics and control efforts (e.g. a near-future vaccine introduction) has become critically important. This study highlights the capacity of multi-level pattern-matching modelling approaches to offer an analytic tool for deeper insights into dengue epidemiology and control.
    Matched MeSH terms: Dengue Virus/classification*
  16. Evolutionary relationships of endemic/epidemic and sylvatic dengue viruses
    Wang E, Ni H, Xu R, Barrett AD, Watowich SJ, Gubler DJ, et al.
    J Virol, 2000 Apr;74(7):3227-34.
    PMID: 10708439
    Endemic/epidemic dengue viruses (DEN) that are transmitted among humans by the mosquito vectors Aedes aegypti and Aedes albopictus are hypothesized to have evolved from sylvatic DEN strains that are transmitted among nonhuman primates in West Africa and Malaysia by other Aedes mosquitoes. We tested this hypothesis with phylogenetic studies using envelope protein gene sequences of both endemic/epidemic and sylvatic strains. The basal position of sylvatic lineages of DEN-1, -2, and -4 suggested that the endemic/epidemic lineages of these three DEN serotypes evolved independently from sylvatic progenitors. Time estimates for evolution of the endemic/epidemic forms ranged from 100 to 1,500 years ago, and the evolution of endemic/epidemic forms represents relatively recent events in the history of DEN evolution. Analysis of envelope protein amino acid changes predicted to have accompanied endemic/epidemic emergence suggested a role for domain III in adaptation to new mosquito and/or human hosts.
    Matched MeSH terms: Dengue Virus/classification
  17. Fulltext Effect of sublethal dosages of malathion on the oral susceptibility of Aedes aegypti to dengue-2 virus infection
    Lee HL, Argubano RA, Ahmad R
    Southeast Asian J. Trop. Med. Public Health, 1997 Sep;28(3):664-5.
    PMID: 9561626
    Matched MeSH terms: Dengue Virus/classification
  18. Fulltext Detection and serotyping of dengue viruses by PCR: a simple, rapid method for the isolation of viral RNA from infected mosquito larvae
    Chan SY, Kautner I, Lam SK
    Southeast Asian J. Trop. Med. Public Health, 1994 Jun;25(2):258-61.
    PMID: 7855637
    Dengue viruses pose a considerable global public health problem with an estimated 100 million cases of illness every year. This illustrates the need for rapid and reliable diagnostic methods for proper patient management and disease control. Currently, laboratory diagnosis depends on serology or virus isolation, with both methods having certain drawbacks. Alternatively, reverse transcription and polymerase chain reaction (RT-PCR) offers the potential for the rapid, highly sensitive and specific detection of dengue viruses. Since we occasionally encounter the problem of insufficient amounts of patient serum for the direct detection of dengue viruses, a method was developed for the extraction of viral RNA after biological amplification in mosquito larvae. Using this method, 15 of 19 clinical samples tested were correctly identified using RT-PCR.
    Matched MeSH terms: Dengue Virus/classification
  19. The 1982 dengue epidemic in Malaysia: epidemiological, serological and virological aspects
    Fang R, Lo E, Lim TW
    Southeast Asian J. Trop. Med. Public Health, 1984 Mar;15(1):51-8.
    PMID: 6740379
    In 1982, Malaysia experienced the worst dengue/dengue haemorrhagic fever outbreak in its history. All states in Peninsular and East Malaysia were similarly affected. There was a total of 3,005 cases with 35 deaths, with the majority of cases occurring between the months of July to October. There was a total of 1,001 laboratory confirmed cases. Most of the cases were in patients over the age of 15 years. The Chinese population was mainly affected, although a much higher proportion of Malays was noted in comparison to previous years. The main serotypes involved were dengue-1 and dengue-3. No dengue-4 serotype were isolated.
    Matched MeSH terms: Dengue Virus/classification
  20. Neurovirulence of four encephalitogenic dengue 3 virus strains isolated in Malaysia (1992-1994) is not attributed to their envelope protein
    Fong MY, Yusup R, Yusof R, Lam SK
    Trans R Soc Trop Med Hyg, 2004 Jun;98(6):379-81.
    PMID: 15099995
    The amino acid sequences of the envelope (E) protein of four encephalitogenic and five non-encephalitogenic dengue 3 virus strains isolated in Malaysia were determined and compared. Multiple sequence alignment revealed a high degree of similarity in the E protein of the strains suggesting that neurovirulence of these four encephalitogenic strains is not attributed to this protein.
    Matched MeSH terms: Dengue Virus/classification
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