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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/transmission*
Fulltext Larvicidal efficacy of different plant parts of railway creeper, Ipomoea cairica Extract Against Dengue Vector Mosquitoes, Aedes albopictus (Diptera: Culicidae) and Aedes aegypti (Diptera: Culicidae)

AhbiRami R, Zuharah WF, Thiagaletchumi M, Subramaniam S, Sundarasekar J

J Insect Sci, 2014;14:180.
PMID: 25368088 DOI: 10.1093/jisesa/ieu042

Natural insecticides from plant origin against mosquito vectors have been the main concern for research due to their high level of eco-safety. Control of mosquitoes in their larval stages are an ideal method since Aedes larvae are aquatic, thus it is easier to deal with them in this habitat. The present study was specifically conducted to explore the larvicidal efficacy of different plant parts of Ipomoea cairica (L.) or railway creeper crude extract obtained using two different solvents; methanol and acetone against late third-stage larvae of Aedes albopictus (Skuse) and Aedes aegypti (L.) (Diptera: Culicidae). Plant materials of I. cairica leaf, flower, and stem were segregated, airdried, powdered, and extracted using Soxhlet apparatus. Larvicidal bioassays were performed by using World Health Organization standard larval susceptibility test method for each species which were conducted separately for different concentration ranging from 10 to 450 ppm. Both acetone and methanol extracts showed 100% mortality at highest concentration tested (450 ppm) after 24 h of exposure. Results from factorial ANOVA indicated that there were significant differences in larvicidal effects between mosquito species, solvent used and plant parts (F=5.71, df=2, P<0.05). The acetone extract of I. cairica leaf showed the most effective larvicidal action in Ae. aegypti with LC50 of 101.94 ppm followed by Ae. albopictus with LC50 of 105.59 ppm compared with other fractions of I. cairica extract obtained from flower, stem, and when methanol are used as solvent. The larvae of Ae. aegypti appeared to be more susceptible to I. cairica extract with lower LC50 value compared with Ae. albopictus (F=8.83, df=1, P<0.05). Therefore, this study suggests that the acetone extract of I. cairica leaf can be considered as plant-derived insecticide for the control of Aedes mosquitoes. This study quantified the larvicidal property of I. cairica extract, providing information on lethal concentration that may have potential for a more eco-friendly Aedes mosquito control program.

Matched MeSH terms: Dengue/transmission
Fulltext Detection of dengue virus from field Aedes aegypti and Aedes albopictus adults and larvae

Ahmad R, Ismail A, Saat Z, Lim LH

Southeast Asian J. Trop. Med. Public Health, 1997 Mar;28(1):138-42.
PMID: 9322296

Mosquito adults and larvae were collected from dengue high risk areas and transported to the laboratory for identification. Identified mosquitos were pooled according to the species, date and locality and stored at -70 degrees C. A total of 1,385 pools of Aedes albopictus and 267 pools of Ae. Aegypti were collected from major towns in 12 states in Peninsular Malaysia. Virus isolation was carried out using cell culture (C6/36 clone) of Ae. albopictus and detection of dengue virus by the peroxidase anti-peroxidase staining. All positive isolations were further re-confirmed by the reverse transcriptase-polymerase chain reaction (RT-PCR). Most of the pools were negative with PAP staining and RT-PCR. However, 11 mosquito pools were positive with PAP staining. On the other hand, samples from Terengganu, Pulau Pinang and Johor were positive using both methods.

Matched MeSH terms: Severe Dengue/transmission*
Dengue hemorrhagic fever rainfall in Penninsular Malyasia: some suggested relationships

Aiken SR, Frost DB, Leigh CH

Soc Sci Med Med Geogr, 1980 Sep;14D(3):307-16.
PMID: 7455728
Matched MeSH terms: Dengue/transmission
Fulltext Pyrethroid resistance in the dengue vector Aedes aegypti in Southeast Asia: present situation and prospects for management

Amelia-Yap ZH, Chen CD, Sofian-Azirun M, Low VL

Parasit Vectors, 2018 Jun 04;11(1):332.
PMID: 29866193 DOI: 10.1186/s13071-018-2899-0

Human arboviral diseases transmitted by Aedes aegypti such as dengue, Zika, chikungunya and yellow fever remain global public health threats to date. Of these diseases, dengue fever is particularly prevalent in Southeast Asia. Relentless vector control efforts are performed to curtail disease transmissions through which pyrethroid insecticides are broadly used as the first line of defense to control Ae. aegypti, especially in the course of disease outbreaks. Here, we compile the largest contemporary database for susceptibility profiles and underlying mechanisms involved in Ae. aegypti resistant to pyrethroids in Southeast Asia. The extensive use of pyrethroids inevitably elicit different levels of resistance to numerous populations despite the presence of geographical isolation. The most common mechanisms of pyrethroid resistance that have been identified in Ae. aegypti includes mutations in the voltage sensitive sodium channel gene (Vssc gene) and metabolic-mediated insecticide resistance. Aedes aegypti develops resistance to pyrethroids by acquisition of one or several amino acid substitution(s) in this Vssc gene. Enzymes involved in metabolic-mediated detoxification (i.e. monooxygenases, glutathione-S-transferases and esterases) have been reported to be related to pyrethroid resistance but many specific contributory enzymes are not completely studied. An inadequate amount of data from some countries indicates an urgent need for further study to fill the knowledge gaps. Perspectives and future research needs are also discussed.

Matched MeSH terms: Dengue/transmission*
Fulltext Stakeholders' attitudes to outdoor residual spraying technique for dengue control in Malaysia: A PLS-SEM approach

Arham AF, Amin L, Mustapa MAC, Mahadi Z, Yaacob M, Ibrahim M

PLoS Negl Trop Dis, 2021 Jun;15(6):e0009493.
PMID: 34185785 DOI: 10.1371/journal.pntd.0009493

Outdoor Residual Spraying (ORS) technique is a complementary preventive measure for dengue. The alarming number of dengue cases in Malaysia requires an alternative method to control dengue besides the traditional method such as fogging. However, the introduction of new technologies depends on social acceptance. Therefore, this study was important to determine the factors that influence stakeholders' attitudes towards the ORS and the moderating factor. A validated instrument was used to randomly interview 399 respondents representing two stakeholder groups which consist of scientists, and the public in Klang Valley, Malaysia. The findings revealed that the stakeholders claimed to have a high degree of religiosity, a high level of trust in the key players, perceived ORS as having high benefits, and displayed highly positive attitudes towards the ORS. The attitudes model towards the ORS model was developed using the SmartPLS software version. The perceived benefit was endorsed as the most important direct predictor of attitudes towards the ORS (ß = 0.618, P<0.001), followed by trust in the key players (ß = 0.151, P<0.001). It is also interesting to note that religiosity served as a moderator for the association between perceived benefit (ß = 0.075, P = 0.024) and perceived risk (ß = 0.114, P = 0.006) with attitudes towards the ORS. The identified predictor factors of stakeholders' attitudes toward the ORS and the moderating factor can serve as indicators for social acceptance of ORS in developing countries. These indicators can help the policymakers in decision making to implement this technique.

Matched MeSH terms: Dengue/transmission
Fulltext Determining the spatial autocorrelation of dengue vector populations: influences of mosquito sampling method, covariables, and vector control

Azil AH, Bruce D, Williams CR

J Vector Ecol, 2014 Jun;39(1):153-63.
PMID: 24820568 DOI: 10.1111/j.1948-7134.2014.12082.x

We investigated spatial autocorrelation of female Aedes aegypti L. mosquito abundance from BG-Sentinel trap and sticky ovitrap collections in Cairns, north Queensland, Australia. BG-Sentinel trap collections in 2010 show a significant spatial autocorrelation across the study site and over a smaller spatial extent, while sticky ovitrap collections only indicate a non-significant, weak spatial autocorrelation. The BG-Sentinel trap collections were suitable for spatial interpolation using ordinary kriging and cokriging techniques. The uses of Premise Condition Index and potential breeding container data have helped improve our prediction of vector abundance. Semiovariograms and prediction maps indicate that the spatial autocorrelation of mosquito abundance determined by BG-Sentinel traps extends farther compared to sticky ovitrap collections. Based on our data, fewer BG-Sentinel traps are required to represent vector abundance at a series of houses compared to sticky ovitraps. A lack of spatial structure was observed following vector control treatment in the area. This finding has implications for the design and costs of dengue vector surveillance programs.

Matched MeSH terms: Dengue/transmission*
Fulltext Household survey of container-breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia

Aziz AT, Dieng H, Ahmad AH, Mahyoub JA, Turkistani AM, Mesed H, et al.

Asian Pac J Trop Biomed, 2012 Nov;2(11):849-57.
PMID: 23569860 DOI: 10.1016/S2221-1691(12)60242-1

To investigate the prevalence of container breeding mosquitoes with emphasis on the seasonality and larval habitats of Aedes aegypti (Ae. aegypti) in Makkah City, adjoining an environmental monitoring and dengue incidence.

Matched MeSH terms: Dengue/transmission
Fulltext Dynamic spatiotemporal trends of dengue transmission in the Asia-Pacific region, 1955-2004

Banu S, Hu W, Guo Y, Naish S, Tong S

PLoS One, 2014;9(2):e89440.
PMID: 24586780 DOI: 10.1371/journal.pone.0089440

BACKGROUND: Dengue fever (DF) is one of the most important emerging arboviral human diseases. Globally, DF incidence has increased by 30-fold over the last fifty years, and the geographic range of the virus and its vectors has expanded. The disease is now endemic in more than 120 countries in tropical and subtropical parts of the world. This study examines the spatiotemporal trends of DF transmission in the Asia-Pacific region over a 50-year period, and identified the disease's cluster areas.
METHODOLOGY AND FINDINGS: The World Health Organization's DengueNet provided the annual number of DF cases in 16 countries in the Asia-Pacific region for the period 1955 to 2004. This fifty-year dataset was divided into five ten-year periods as the basis for the investigation of DF transmission trends. Space-time cluster analyses were conducted using scan statistics to detect the disease clusters. This study shows an increasing trend in the spatiotemporal distribution of DF in the Asia-Pacific region over the study period. Thailand, Vietnam, Laos, Singapore and Malaysia are identified as the most likely clusters (relative risk = 13.02) of DF transmission in this region in the period studied (1995 to 2004). The study also indicates that, for the most part, DF transmission has expanded southwards in the region.
CONCLUSIONS: This information will lead to the improvement of DF prevention and control strategies in the Asia-Pacific region by prioritizing control efforts and directing them where they are most needed.

Matched MeSH terms: Dengue/transmission*
Fulltext Dengue and dengue haemorrhagic fever outbreak in Lawas District, Sarawak, East Malaysia

Chang MS, Jute N

Med J Malaysia, 1986 Dec;41(4):310-9.
PMID: 3670153

An outbreak of Dengue and Dengue Harmorrhagic Fever occurred in Lawas District in 1983. A total of 134 cases were notified with 74 cases serologically confirmed. The epidemic which lasted for three months starting from week 20 and peaking in week 24 before being brought under control in week 35 is the first to occur in the district. At the end of the epidemic, 54 localities were affected starting from areas within the vicinity of the town before spreading further inland with the movement of the population.
Entomological investigation in all the infected areas revealed a high density of Aedes albopictus which was the sole vector present. Effective control of the epidemic was achieved through proper planning, active participation of various agencies and intensive outdoor spraying with malathion 2% or ULV concentrates.

Matched MeSH terms: Dengue/transmission
Fulltext Laboratory-Based Surveillance and Molecular Characterization of Dengue Viruses in Taiwan, 2014

Chang SF, Yang CF, Hsu TC, Su CL, Lin CC, Shu PY

Am J Trop Med Hyg, 2016 Apr;94(4):804-11.
PMID: 26880779 DOI: 10.4269/ajtmh.15-0534

We present the results of a laboratory-based surveillance of dengue in Taiwan in 2014. A total of 240 imported dengue cases were identified. The patients had arrived from 16 countries, and Malaysia, Indonesia, the Philippines, and China were the most frequent importing countries. Phylogenetic analyses showed that genotype I of dengue virus type 1 (DENV-1) and the cosmopolitan genotype of DENV-2 were the predominant DENV strains circulating in southeast Asia. The 2014 dengue epidemic was the largest ever to occur in Taiwan since World War II, and there were 15,492 laboratory-confirmed indigenous dengue cases. Phylogenetic analysis showed that the explosive dengue epidemic in southern Taiwan was caused by a DENV-1 strain of genotype I imported from Indonesia. There were several possible causes of this outbreak, including delayed notification of the outbreak, limited staff and resources for control measures, abnormal weather conditions, and a serious gas pipeline explosion in the dengue hot spot areas in Kaohsiung City. However, the results of this surveillance indicated that both active and passive surveillance systems should be strengthened so appropriate public health measures can be taken promptly to prevent large-scale dengue outbreaks.

Matched MeSH terms: Dengue/transmission
Fulltext Weekly variation on susceptibility status of Aedes mosquitoes against temephos in Selangor, Malaysia

Chen CD, Nazni WA, Lee HL, Sofian-Azirun M

Trop Biomed, 2005 Dec;22(2):195-206.
PMID: 16883288 MyJurnal

Larvae of Aedes aegypti and Aedes albopictus obtained from 6 consecutive ovitrap surveillance (OS) in Taman Samudera and Kg. Banjar were evaluated for their susceptibility to temephos. Larval bioassays were carried out in accordance with WHO standard methods, with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos respectively. Aedes aegypti and Ae. albopictus obtained from six OS in Taman Samudera showed resistance to diagnostic dosage of temephos with percentage mortality between 5.3 to 72.0 and 9.3 to 56.0, respectively, while Ae. aegypti and Ae. albopictus obtained from Kg. Banjar showed resistance to temephos with percentage mortality between 16.0 to 72.0 and 0 to 50.6, respectively. Only two strains of Ae. aegypti from Kg. Banjar were susceptible to temephos with 93.3% (OS 2) and 100% (OS 3) mortality. The 50% mortality at lethal time (LT50) for all strains of Ae. aegypti and Ae. albopictus tested against operational dosage of temephos showed range between 36.07 to 75.69 minutes and 58.65 to 112.50 minutes, respectively, and complete mortality was achieved after 24 hours. Our results indicated that there is weekly variations of the resistance status for Ae. aegypti and Ae. albopictus. Aedes susceptibility to temephos is changing from time to time in these two study sites. It is essential to continue monitoring the resistance of this vector to insecticides in order to ensure the efficiency of program aimed at vector control and protection of human health.

Matched MeSH terms: Dengue/transmission
Fulltext Mixed breeding of Aedes aegypti (L.) and Aedes albopictus Skuse in four dengue endemic areas in Kuala Lumpur and Selangor, Malaysia

Chen CD, Nazni WA, Lee HL, Seleena B, Mohd Masri S, Chiang YF, et al.

Trop Biomed, 2006 Dec;23(2):224-7.
PMID: 17322826 MyJurnal

Ovitrap surveillance was conducted in four dengue endemic areas in Kuala Lumpur and Selangor, Malaysia to determine the distribution and percentage of mixed breeding of both Aedes aegypti and Aedes albopictus. The percentage of mixed breeding in all study sites both indoors and outdoors accounted for 10 to 32 % from the total ovitraps collected. Ae. aegypti was found at a higher frequency than Ae. albopictus in these ovitraps. This study again indicates that ovitrap is a sensitive tool to attract gravid females of more than one mosquito species to oviposit in the container.

Matched MeSH terms: Dengue/transmission*
Fulltext Dengue vector surveillance in urban residential and settlement areas in Selangor, Malaysia

Chen CD, Benjamin S, Saranum MM, Chiang YF, Lee HL, Nazni WA, et al.

Trop Biomed, 2005 Jun;22(1):39-43.
PMID: 16880752

Ovitrap surveillance was conducted in two urban residential areas (Taman Samudera Timur and Taman Samudera Selatan) and in a settlement area (Kampung Banjar), which is located 16 km from Kuala Lumpur city center, Malaysia. In Taman Samudera, dengue cases were reported monthly in 2003/2004. Thus, a study was initiated to determine the distribution and abundance of dengue vectors, Aedes aegypti and Ae. albopictus. The ovitrap surveillance indicated that Ae. aegypti and Ae. albopictus were present both indoors and outdoors. The residential sites had 73 - 79% of the ovitraps with just Ae. aegypti population and Kg. Banjar had 56% of the ovitraps with just Ae. aegypti. In the indoor and outdoor of the residential areas, together with the settlement area, the Ae. aegypti density was significantly more than Ae. albopictus (p < 0.05) by 3 - 50 folds. There was no significant difference in the larval numbers of Ae. aegypti between indoors and outdoors (p > 0.05), thus implicating that adult gravid female Ae. aegypti are present both indoors and outdoors and they do oviposit indoors and outdoors. Ae. aegypti can be incriminated as the principal dengue vector in the urban residential site, Taman Samudera and in the settlement area, Kg. Banjar.

Matched MeSH terms: Dengue/transmission*
Fulltext Acute dengue in a neonate secondary to perinatal transmission

Chin PS, Khoo AP, Asmah Hani AW, Chem YK, Norizah I, Chua KB

Med J Malaysia, 2008 Aug;63(3):265-6.
PMID: 19248708 MyJurnal

We report a newborn baby girl with acute dengue due to vertical transmission. A 31 year old factory worker of 38+ week gestation, gravida 5 para 3+1, developed acute dengue fever two days prior to delivery. She delivered a normal term baby girl by spontaneous vaginal delivery and recovered uneventfully without peripartum haemorrhage despite the presence of thrombocytopenia. The baby girl developed low grade fever on day four of post-natal life and except for the transient thrombocytopenia, also recovered uneventfully following three days of mild illness. The clinical diagnosis of acute dengue virus infection was confirmed by laboratory tests.

Matched MeSH terms: Dengue/transmission*
Preliminary study of dengue virus infection in Iran

Chinikar S, Ghiasi SM, Shah-Hosseini N, Mostafavi E, Moradi M, Khakifirouz S, et al.

Travel Med Infect Dis, 2013 May-Jun;11(3):166-9.
PMID: 23194952 DOI: 10.1016/j.tmaid.2012.10.001

Dengue fever is one of the most important arthropod-borne viral diseases of public health significance. It is endemic in most tropical and subtropical parts of the world, many of which are popular tourist destinations. The presence of dengue infection was examined in Iranian patients who were referred to the Arboviruses and Viral Haemorrhagic Fevers Laboratory of the Pasteur Institute of Iran and tested negative for Crimean-Congo Haemorrhagic Fever (CCHF) between 2000 and 2012. Serum samples from these patients were tested for the presence of specific IgG and IgM and viral nucleic acid in blood. Of the 300 sera tested, 15 (5%) were seropositive, and 3 (1%) were both serologically and PCR positive. Of the 15 seropositive cases, 8 (53.3%) had travelled to endemic areas including Malaysia (5, 62.5%), India (2, 25%) and Thailand (1, 12.5%). In contrast, 7 (46.7%) of the cases had not reported travelling abroad. Of these, six cases were from the Sistan and Baluchistan province in southeast Iran and neighbouring Pakistan. Travellers play a key role in the epidemiology of dengue infection in Iran and it is recommended that travellers to endemic areas take precautionary measures to avoid mosquito bites.

Matched MeSH terms: Dengue/transmission
Fulltext Current vector research challenges in the greater Mekong subregion for dengue, Malaria, and Other Vector-Borne Diseases: A report from a multisectoral workshop March 2019

Christofferson RC, Parker DM, Overgaard HJ, Hii J, Devine G, Wilcox BA, et al.

PLoS Negl Trop Dis, 2020 Jul;14(7):e0008302.
PMID: 32730249 DOI: 10.1371/journal.pntd.0008302
Matched MeSH terms: Dengue/transmission*
Vertical transmission of dengue

Chye JK, Lim CT, Ng KB, Lim JM, George R, Lam SK

Clin Infect Dis, 1997 Dec;25(6):1374-7.
PMID: 9431381

Dengue, an important mosquito-borne flavivirus infection, is endemic in Southeast Asia. We describe two mothers who had acute dengue 4 and 8 days before the births of their infants. One mother had worsening of her proteinuric pregnancy-induced hypertension, liver dysfunction, and coagulopathy and required multiple transfusions of whole blood, platelets, and fresh frozen plasma. Her male infant was ill at birth, developed respiratory distress and a large uncontrollable left intracerebral hemorrhage, and died of multiorgan failure on day 6 of life. Dengue virus type 2 was isolated from the infant's blood, and IgM antibody specific to dengue virus was detected in the mother's blood. The second mother had a milder clinical course; she gave birth to a female infant who was thrombocytopenic at birth and had an uneventful hospitalization. Dengue virus type 2 was recovered from the mother's blood, and IgM antibody specific to dengue virus was detected in the infant's blood. This report highlights not only the apparently rare occurrence of vertical transmission of dengue virus in humans but also the potential risk of death for infected neonates.

Matched MeSH terms: Dengue/transmission*
Fulltext Potential impact of dengue vaccination: Insights from two large-scale phase III trials with a tetravalent dengue vaccine

Coudeville L, Baurin N, L'Azou M, Guy B

Vaccine, 2016 12 07;34(50):6426-6435.
PMID: 27601343 DOI: 10.1016/j.vaccine.2016.08.050

BACKGROUND: A tetravalent dengue vaccine demonstrated its protective efficacy in two phase III efficacy studies. Results from these studies were used to derive vaccination impact in the five Asian (Indonesia, Malaysia, Philippines, Thailand, Vietnam) and the five Latin American countries (Brazil, Colombia, Honduras, Mexico and Puerto Rico) participating in these trials.
METHODS: Vaccination impact was investigated with an age-structured, host-vector, serotype-specific compartmental model. Parameters related to vaccine efficacy and levels of dengue transmission were estimated using data collected during the phase III efficacy studies. Several vaccination programs, including routine vaccination at different ages with and without large catch-up campaigns, were investigated.
RESULTS: All vaccination programs explored translated into significant reductions in dengue cases at the population level over the first 10years following vaccine introduction and beyond. The most efficient age for vaccination varied according to transmission intensity and 9years was close to the most efficient age across all settings. The combination of routine vaccination and large catch-up campaigns was found to enable a rapid reduction of dengue burden after vaccine introduction.
CONCLUSION: Our analysis suggests that dengue vaccination can significantly reduce the public health impact of dengue in countries where the disease is endemic.

Matched MeSH terms: Dengue/transmission*
Sterile mosquitoes near take-off

Cyranoski D

Nature, 2008 May 22;453(7194):435.
PMID: 18497781 DOI: 10.1038/453435a
Matched MeSH terms: Dengue/transmission*

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