Nazri Che Dom

Spatial mapping of temporal risk characteristic of dengue cases in Subang Jaya

Dengue has become the most widespread vector borne viral diseases of human with the rough estimate of between 60 and 100 million cases of dengue fever worldwide annually. This study proposed a new set of parameters which defined dengue occurrence at an area according to its time characteristics. The objectives of this study were to measure the temporally defined risk indices, to map the measured temporal risk indices and to statistically prove the relationship between each temporal risk indices. Measurement of the three temporal risk indices found that there were areas with significant high value for each of the temporal indices. This suggested that areas within Subang Jaya Municipality had different temporal characteristics for dengue occurrence. The value of frequency index was quite low which was below the minimum of 1. 1 indicates that dengue will occur every week throughout the year. The mean value of duration index was 1.66 which pointed out that the mean duration of an epidemic wave was about 2 weeks. 5.41 was the mean value for intensity index and it signified that during an epidemic wave, about 5 to 6 people in a population of 1000 would be infected by dengue fever. Mapping, which is a spatial analysis method, is utilized for the visual analysis of the three temporal indices. It was found that most areas had high frequency indices. Visual analysis of the duration index showed that there was a distribution pattern where areas with a history of high duration per wave would experience it in the future. There is no significant distribution pattern for intensity index as the high value tended to stay at the same locality throughout the years. Three types of relationship, frequency-duration relation, frequency-intensity relation and duration-intensity relation were identified. The correlation coefficient for all the three types of relationship was above 0.7. The value indicated that there was a strong correlation between each temporal risk indices. As a recommendation, the temporal risk indices can be utilized by public health officials to characterize dengue rather than relying on the traditional case incidence data.

Profile distribution of juvenile Aedes species in an urban area of Malaysia

BACKGROUNDnDengue fever (DF) is an urban vector-borne disease transmitted by Aedes aegypti and Aedes albopictus. Both species deposit their eggs in favorable breeding sites either in natural or artificial containers. An understanding of their habitat characteristics is crucial in curbing DF outbreaksnnnMETHODSnA search and destroy survey was carried out at 10 dengue hotspot localities in Shah Alam, Malaysia. A quantitative in-situ measurement of selected physical parameters was conducted focusing on the environmental characteristics and the presence of vegetation. Larvae and pupae found in different types of container were morphologically identified.nnnRESULTSnEvidence of breeding was discovered in 62 containers. Rubber materials (container efficiency: 2.10), with clear water in the presence of dead vegetation (71 and 33% respectively) were found to be most efficient for pupae development. Furthermore, low water volume (60%) was preferred for breeding purposes. Kruskal-Wallis test demonstrated that water volume, wind velocity and distance from habitation were statistically significant towards dengue vectors.nnnCONCLUSIONSnOur findings have provided the profile of Aedes species based on environmental and water conditions in hotspot areas in Malaysia. These outcomes provide useful information regarding container characteristics that can enable selective elimination of vector habitat thus minimizing the risk of dengue outbreak.

Dengue cases distribution based on land surface temperature and elevation

Dengue fever is a major infection among of the mosquito-borne viral diseases. It became viral globally. Malaysia is one of the countries that has a dengue fever crisis. The case rate of dengue in Malaysia remains high. The impact of this situation, a high number of human morbidity and mortality was reported. Presently, the cure of dengue is unavailable. Besides, the current method which is fogging also unable to eliminate the disease permanently. The best way is prevention through controlling the dengue outbreak. Thus, a thorough understanding of what factors affected the transmission of dengue is vital for effective controlling the disease. Environmental factors are commonly associated with spreading dengue fever. One of environment factors affected dengue is temperature. In this paper, an association between land surface temperature (LST), elevation, and dengue be studied. Therefore, the application of spatial analysis using geographical information system (GIS) and the remote sensing image was adopted in this study. These techniques are essential in controlling dengue outbreak as analysis of potentially high-risk areas in urban areas by using environmental factors as indicators. Dengue distribution patterns can be visualized and distribution of dengue and environmental factors can be determined. In other words, the dengue distribution maps produced can be used as a guide for public health management.

Application of geographical information system-based analytical hierarchy process as a tool for dengue risk assessment

Abstract Objective To highlight the use of analytical hierarchy process (AHP) in geographical information system that incorporates environmental indices to generate dengue risk zonation area. Methods The medical database considered for the study was referenced to the environmental data layers. Factors related to the risk of dengue fever (DF) were selected throughout previous research and were arranged in a hierarchical structure. The relative weights of factors were calculated, which were within acceptable range with the consistency ratio being less than 0.1. The outcomes from AHP based DF risk zonation area produced useful information on different levels of risks. Results As a result, factor weights used in AHP were evaluated and found to be acceptable as the consistency ratio of 0.05, which was Conclusions This attempt, if successful, will have significant implications that could strengthen public health interventions and offers priorities in designing the most optimum and sustainable control program to combat dengue in Malaysia.

A profile of noise sensitivity on the health-related quality of life among young motorcyclists

Introduction: Motorcycle riders with noise sensitivity (NS) may suffer from degraded health-related quality of life (HRQOL) because they are exposed to acute noise levels on a daily basis. Materials and Methods: This study was aimed to identify the relationship between NS and HRQOL among young motorcycle riders (undergraduate university students) aged between 19 and 25 years (nu2009=u2009301) through a cross-sectional questionnaire-based study, that is, Weinstein noise sensitivity scale and the World Health Organization Quality of Life. The effects of NS on HRQOL were assessed based on gender, the years of motorcycle driving experience, and noise sensitive among groups using one-way analysis of variances with an alpha value of 0.05. Results: The results showed no significant difference in NS between males and females. On the other hand, motorcycle driving experience for <4 years displayed a higher tendency toward NS. Moreover, a significantly (Pu2009=u20090.004) decreasing trend among low, moderate, and high NS with their respective HRQOL was observed, while a high NS showed significantly (Pu2009=u20090.015) lower scores on the social domain of the quality of life. Conclusion: The overall premise of the study has statistical significance and shows that individuals with high NS tend to have degraded HRQOL compared to individuals with low NS. Furthermore, in-depth studies are required from the other demographical background of participants to investigate the motorcyclist’s NS and HRQOL as an integral requirement for the rider’s safety and health.

The Genetic Diversity, Haplotype Analysis, and Phylogenetic Relationship of Aedes albopictus (Diptera: Culicidae) Based on the Cytochrome Oxidase 1 Marker: A Malaysian Scenario

Abstract The global expansion of Ae. albopictus from its native range in Southeast Asia has been implicated in the recent emergence of dengue endemicity in Malaysia. Genetic variability studies of Ae. albopictus are currently lacking in the Malaysian setting, yet are crucial to enhancing the existing vector control strategies. The study was conducted to establish the genetic variability of maternally inherited mitochondrial DNA encoding for cytochrome oxidase subunit 1 (CO1) gene in Ae. albopictus. Twelve localities were selected in the Subang Jaya district based on temporal indices utilizing 120 mosquito samples. Genetic polymorphism and phylogenetic analysis were conducted to unveil the genetic variability and geographic origins of Ae. albopictus. The haplotype network was mapped to determine the genealogical relationship of sequences among groups of population in the Asian region. Comparison of Malaysian CO1 sequences with sequences derived from five Asian countries revealed genetically distinct Ae. albopictus populations. Phylogenetic analysis revealed that all sequences from other Asian countries descended from the same genetic lineage as the Malaysian sequences. Noteworthy, our study highlights the discovery of 20 novel haplotypes within the Malaysian population which to date had not been reported. These findings could help determine the genetic variation of this invasive species, which in turn could possibly improve the current dengue vector surveillance strategies, locally and regionally.