Siriwan Wongkoon

Walailak University, Nakhon Si Thammarat, Changwat Nakhon Si Thammarat, Thailand

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Publications (13)5.01 Total impact

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    ABSTRACT: This study explored the impact of weather variability on the transmission of dengue fever in Nakhon Si Thammarat, Thailand. Data on monthly-notified cases of dengue fever, over the period of January 1981 - June 2012 were collected from the Bureau of Epidemiology, Department of Disease Control, Ministry of Public Health. Weather data over the same period were obtained from the Thai Meteorological Department. Spearman correlation analysis and time-series adjusted Poisson regression analysis were performed to quantify the relationship between weather and the number of dengue cases. The results showed that maximum and minimum temperatures at a lag of zero months, the amount of rainfall, and relative humidity at a lag of two months were significant predictors of dengue incidence in Nakhon Si Thammarat. The time series Poisson regression model demonstrated goodness-of-fit with a correlation between observed and predicted number of dengue incidence rate of 91.82%. This model could be used to optimise dengue prevention by predicting trends in dengue incidence. Accurate predictions, for even a few months, provide an invaluable opportunity to mount a vector control intervention or to prepare for hospital demand in the community.
    Tropical biomedicine 12/2013; 30(4):631-41. · 0.92 Impact Factor
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    ABSTRACT: Background & objectives : Environmental factors including weather variables may play a significant role in the transmission of dengue. This study investigated the effect of seasonal variation on the abundance of Aedes aegypti and Ae. albopictus larvae and explored the impact of weather variability on dengue transmission in Sisaket, Thailand. Methods : The monthly mosquito larval surveys were carried out in urban and rural areas in Sisaket, Thailand from January to December 2010. Data on monthly-reported cases of dengue fever over the period 2004-2010 were obtained from the Ministry of Public Health. Weather data over the same period were obtained from the Thai Meteorological Department. Chi-square test was used to find the differences relating to seasonal variability, areas of study, and mosquito species factors using entomological survey data. Time series Poisson regression analysis was performed using data on monthly weather variables and dengue cases. Results : There were more Ae. aegypti larvae per household than Ae. albopictus larvae in the winter and rainy seasons. More Aedes larvae per household were found in the rainy season than in the winter and summer seasons. Relative humidity at a lag of one month and rainy days in the current month were significant predictors of dengue incidence in Sisaket. Interpretation & conclusions : Increased rain during the current month and less humidity during the previous month might trigger a higher incidence of dengue epidemic in Sisaket. The present findings suggest that the dengue incidence corresponds with the number of Aedes larvae. The seasonal patterns of dengue outbreaks coincide with the rainy season.
    The Indian Journal of Medical Research 09/2013; 138(3):347-53. · 2.06 Impact Factor
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    ABSTRACT: The Mosquito Online Advanced Analytic Service (MOAAS) provides an essential tool for querying, analyzing, and visualizing patterns of mosquito larval distribution in Thailand. The MOAAS was developed using Structured Query Language (SQL) technology as a web-based tool for data entry and data access, webMathematica technology for data analysis and data visualization, and Google Earth and Google Maps for Geographic Information System (GIS) visualization. Fifteen selected schools in Thailand provided test data for MOAAS. Users performed data entry using the web-service, data analysis, and data visualization tools with webMathematica, data visualization with bar charts, mosquito larval indices, and three-dimensional (3D) bar charts overlaying on the Google Earth and Google Maps. The 3D bar charts of the number of mosquito larvae were displayed along with spatial information. The mosquito larvae information may be useful for dengue control efforts and health service communities for planning and operational activities.
    The Southeast Asian journal of tropical medicine and public health 07/2013; 44(4):574-85. · 0.61 Impact Factor
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    ABSTRACT: This study aimed at developing a predicting model on the incidence rate of dengue fever in four locations of Thailand - i.e. the northern region, Chiang Rai province, the north-eastern region and Sisaket province - using time series analysis. Seasonal Autoregressive Integrated Moving Average (SARIMA) model was performed using data on monthly incidence rate of dengue fever from 1981 to 2009, and validated using the monthly rate collected for the period January 2010 to October 2011. The results show that the SARIMA(1,0,1)(0,1,1)12 model is the most suitable model in all locations. The model for all locations indicated that the predicted dengue incidence rate and the actual dengue incidence rate matched reasonably well. The model was further validated by the Portmanteau test with no significant autocorrelation between residuals at different lag times. Our findings indicate that SARIMA model is a useful tool for monitoring dengue incidence in Thailand. Furthermore, this model can be applied to surveillance data for early warning systems for control and reduction of dengue transmission.
    Tropical biomedicine 09/2012; 29(3):339-48. · 0.92 Impact Factor
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    ABSTRACT: To model the monthly number of dengue fever cases in northeastern Thailand using time series analysis. Autoregressive Integrated Moving Average (ARIMA) models have been developed on the monthly data collected from January 1981 to December 2006 and validated using the data from January 2007 to April 2010. The ARIMA (3,1,4) model has been found as the most suitable model with the least Akaike Information Criterion (AIC) of 14.060 and Mean Absolute Percent Error (MAPE) of 7.000. The model was further validated by the Portmanteau test with no significant autocorrelation between residuals at different lag times. Early warning based on the data in the previous months could assist in improving vector control, community intervention, and personal protection.
    Asian Pacific Journal of Tropical Medicine 03/2012; 5(3):249-52. · 0.50 Impact Factor
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    ABSTRACT: This study investigated the numbers of Aedes larvae found in relation to the religion of the people, the location of their houses, and the number of water containers in and around the house. We collected our questionnaire survey during April-May 2004 covering two different topographical areas (i.e. seaside and mountainous areas) and two religious factors (i.e. Buddhist and Muslims). We collected samples by using the stratified simple random sampling with a total of 400 households from all communities in 31 sub-districts. The results showed that there were a higher number of Ae. aegypti larvae in water containers in bathrooms, concrete tanks and large water jars than the number of Ae. albopictus larvae in both areas. Ae. albopictus larvae were found in higher numbers at the seaside area than in the mountainous area. On the other hand, the number of small water jars had a higher number of Aedes larvae in the mountainous area than in the seaside area. Considering only large water jars, covers apparently reduced the number of Ae. aegypti and other mosquito larvae. Regardless of the kind of cover, uncovered containers had more mosquito larvae than covered containers. More Ae. aegypti larvae were found in larger jars than in smaller jars and we also found more Ae. aegypti larvae in smaller jars which were
    01/2011;
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    ABSTRACT: This study aims at estimating coral growth forms at Racha Islands, Phuket. We use random sampling techniques. We took coral photographs with a digital camera and underwater casing. Coral images were classified into one of seven coral forms and used these percentages to calculate coral biodiversity indices (i.e. Shannon-Wiener index and Simpson index). The percentage of coral growth forms was different. The most common growth form was the foliaceous form. The second common coral growth form was the encrusting form. There were few columnar and free living growth forms at Racha Islands. There were very high biodiversity indices at Racha Islands estimating from coral growth forms. This study suggests that coral reef at Racha Islands is still in prime condition. Introduction Coral reef ecosystems are highly valued as biological, ecological, cultural, and economic resources. In the past few decades, competing demands on coral reef ecosystems and increasing threats from both natural and anthropogenic stressors have contributed to a significant decline in coral reef health worldwide (1,2). This study aim at study coral growth forms, biodiversity index, light intensity and water temperature at coral reef habitat at Racha Islands, Phuket. We estimated seven coral reef growth forms using random sampling techniques. These percentages of coral growth forms were used to estimate coral biodiversity. Methodology: This study was undertaken at Racha Islands, Phuket province, Thailand (Figure 1). Coral reefs in this area were 1-5 m depth. We used a random sampling technique to estimate coral growth forms. We took coral photographs with digital cameras, Canon Power Shot A620 and Olympus uD600/S600 with underwater casings. We used the digital cameras, swam in
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    ABSTRACT: This study investigated how the seasons affect the development sites of Aedes larvae in three topographical areas: mangrove, rice paddy fields and mountainous areas. We examined how the number of Aedes larvae varied in different types of water containers. Water containers were categorized into the following groups: indoor/outdoor containers, artificial/natural containers, earthen/plastic containers, containers with/without lids and dark/light-coloured containers. Samples were collected from 300 households in both the wet and dry seasons from three topographical areas in Nakhon Si Thammarat province with 100 households per topographical area. The results showed that in the wet season, there were higher numbers of Ae. aegypti and Ae. albopictus larvae than in the dry season. Moreover, the number of Ae. albopictus larvae was higher in mountainous areas than in mangrove and rice paddy areas, in both the wet and dry seasons. The number of positive containers was higher in outdoor containers than in indoor containers, higher in artificial containers than natural containers, higher in earthen containers than plastic containers, higher in containers without lids than containers with lids, and higher in the dark-coloured containers than light-coloured containers in the three topographical areas in both wet and dry seasons. The number of positive earthen containers was higher in mangrove areas than in rice paddy and mountainous areas. The number of positive plastic containers was higher in rice paddy areas than mountainous and mangrove areas.
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    ABSTRACT: This study investigated the number of Aedes larvae found in two different topographical areas (i.e. seaside and mountainous area) and two religions (i.e. Buddhist and Muslims). We collected samples by using the stratified simple random sampling with a total of 400 households from all communities in 31 sub-districts. The results showed that Aedes larvae were mostly found in artificial containers including water containers in bathrooms, potted plants, animal pans, concrete tanks and water jars. Aedes albopictus larvae were found at a higher number in the seaside area than in the mountainous area. All three Aedes larval indices: Container Index, House Index and Breteau Index indicated high risk of DHF transmission in this area. We also found that House Index in Muslim households was more than in Buddhist households. Introduction: Dengue fever is caused by dengue viruses, transmitted principally by Aedes aegypti and possible Ae. albopictus mosquitoes in the tropical and subtropical regions of the world (Stephenson et al., 2003). In some peculiar epidemiological situation, depending on the virus characteristics circulating and host immune status it manifests as a complication of dengue infection with signs of Haemorrhage and shock. These two clinical features named Dengue Haemorrhagic Fever (DHF) and Dengue shock syndrome (DSS), if not properly managed, may lead to death (National Institute of Communicable Diseases, 2001; Jacobs et al., 2002). Dengue epidemics have been happening for a long time but DHF is still a major health problem in Thailand. Especially in Nakhon Si Thammarat province that is located in southern part of Thailand. The province still has high outbreaks of this disease (Nakhon Si Thammarat Provincial Health Office, 2002). There are several factors affecting incidence of DHF including water storage, climatic and vector factors. Because preventative care is an increasingly important part of the strategy, social factors that influence its use must be more closely investigated (Benjamins and Brown, 2004). This study was conducted to quantify the
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    ABSTRACT: This study investigated the number of Aedes larvae, the key breeding sites of Aedes sp., and the relationship between climatic factors and the incidence of DHF in Samui Islands. We conducted our questionnaire and larval surveys from randomly selected 105 households in Samui Islands in July-September 2006. Pearson's correlation coefficient was used to explore the primary association between the DHF incidence and all climatic factors. Multiple stepwise regression technique was then used to fit the statistical model. The results showed that the positive indoor containers were small jars, cement tanks, and plastic tanks. The positive outdoor containers were small jars, cement tanks, plastic tanks, used cans, tires, plastic bottles, discarded objects, pot saucers, plant pots, and areca husks. All Ae. albopictus larval indices (i.e., CI, HI, and BI) were higher than Ae. aegypti larval indices in this area. These larval indices were higher than WHO standard. This indicated a high risk of DHF transmission at Samui Islands. The multiple stepwise regression model was y = -288.80 + 11.024xmean temp. The mean temperature was positively associated with the DHF incidence in this area.
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    ABSTRACT: This study aims at estimating coral growth forms at Khanom - Mu Koh Tale Tai Marine National Park. Two techniques were used to estimate coral growth forms: random and quadrat sampling techniques. Researcher took coral photographs with a digital camera and underwater casing. Coral images were classified into one of seven coral forms and used these percentages to calculate coral biodiversity indices (i.e. Shannon-Wiener index and Simpson index). The biodiversity indices did not differ among two techniques. Introduction: Coral reefs are ecosystems of high biodiversity which having the greatest number of species of any marine ecosystem. Unfortunately, the condition of many of the world's coral reefs has reached a crisis point. In addition to the general trend toward reef degradation has addressed the question of acute problems, and has estimated that as much as 10 % of the global reef area has been degraded beyond recovery, with another 30% predicted to collapse within the next 10-20 years (1-3). The reefs at greatest risk are those in Southeast, East and South Asia, East Africa, and the Caribbean. Coral bleaching world wide including Thailand is largely related to the warming of sea water (2-5). This study is a part of long term coral reef monitoring project. This study aims at comparing two techniques that commonly used in coral reef studies. To estimate seven coral reefs growth forms using random and quadrat sampling techniques at three locations. These percentages of coral growth forms were used to estimate coral biodiversity. Methodology: This study was undertaken at three locations: Koh Tan (เกาะแตน, S1), Koh Mud Soom
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    ABSTRACT: This study aimed at developing a forecasting model on the number of Dengue Haemorrhagic Fever (DHF) incidence in Northern Thailand using time series analysis. We developed Seasonal Autoregressive Integrated Moving Average (SARIMA) models on the data collected between 2003-2006 and then validated the models using the data collected between January-September 2007. The results showed that the regressive forecast curves were consistent with the pattern of actual values. The most suitable model was the SARIMA(2,0,1)(0,2,0)12 model with a Akaike Information Criterion (AIC) of 12.2931 and a Mean Absolute Percent Error (MAPE) of 8.91713. The SARIMA(2,0,1)(0,2,0)12 model fitting was adequate for the data with the Portmanteau statistic Q20 = 8.98644 ( = 27.5871, P>0.05). This indicated that there was no significant autocorrelation between residuals at different lag times in the SARIMA(2,0,1)(0,2,0)12 model.
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    ABSTRACT: Objective: The objective of this study was to assess the impact of climate variation on the dengue virus transmission in Chiang Rai, Thailand. Materials and Methods: We obtained population – based information on monthly variation in monthly dengue cases and climatic factors. A time series analysis was conducted by using cross-correlation function and seasonal auto-regressive integrated moving average (SARIMA) mode-ling. Results and Conclusions: Our findings indicate that rainfall and minimum temperature seem to have played an important role in the transmission of dengue in Chiang Rai. Such model may be used to assist public health decision – making and environmental health risk management. Early warning based on forecasts could assist in improving vector control, community intervention, and personal protection.

Publication Stats

19 Citations
5.01 Total Impact Points

Institutions

  • 2012–2013
    • Walailak University
      • School of Science
      Nakhon Si Thammarat, Changwat Nakhon Si Thammarat, Thailand
  • 2011
    • Nakhon Si Thammarat Rajabhat University
      Changwat Nakhon Si Thammarat, Nakhon Si Thammarat, Thailand