Universal Journal of Public Health 9(3): 120-130, 2021 http://www.hrpub.org DOI: 10.13189/ujph.2021.090303 Spatio-Temporal Clustering of Dengue Incidence Nik Nur Fatin Fatihah Sapri1, Wan Fairos Wan Yaacob2,*, Yap Bee Wah1, 3 Syed Sharizman Syed Abdul Rahim 1Faculty of Mathematical and Computer Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Malaysia 2Faculty of Mathematical and Computer Sciences, Universiti Teknologi MARA Cawangan Kelantan Kampus Kota Bharu, 15050 Kota Bharu, Kelantan, Malaysia 3Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Jalan UMS, 88400 Sabah, Malaysia Received January 1, 2021; Revised February 10, 2021; Accepted March 20, 2021 Cite This Paper in the following Citation Styles (a): [1] Nik Nur Fatin Fatihah Sapri, Wan Fairos Wan Yaacob, Yap Bee Wah, Syed Sharizman Syed Abdul Rahim , "Spatio-Temporal Clustering of Dengue Incidence," Universal Journal of Public Health, Vol. 9, No. 3, pp. 120 - 130, 2021. DOI: 10.13189/ujph.2021.090303. (b): Nik Nur Fatin Fatihah Sapri, Wan Fairos Wan Yaacob, Yap Bee Wah, Syed Sharizman Syed Abdul Rahim (2021). Spatio-Temporal Clustering of Dengue Incidence. Universal Journal of Public Health, 9(3), 120 - 130. DOI: 10.13189/ujph.2021.090303. Copyright©2021 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract Dengue fever is a well-known vector-borne transmitted to human body as susceptible host through disease caused by Aedes aegypti mosquito. It has become a biting of infective female Aedes Aegypti mosquitos. major burden to economy and society of affected country. Commonly, people will contract dengue fever after they In Malaysia, dengue incidence in Selangor has been are infected by one of the serotypes namely DEN-V 1, worsening and alarming. The aim of this study is two-fold; DEN-V 2, DEN-V 3 and DEN-V 4 [1]. The severe to examine the trend and behaviour of dengue incidence infection of this virus causes dengue hemorrhagic fever or across time and districts in Selangor and to cluster the dengue shock syndrome which can cause fatality. This endemic areas in Selangor using Wards hierarchical vector-borne disease has emerged as a global health clustering method. The spatial and temporal analysis found problem since 1950s [2]. World Health Organization that the dengue incidence is worsening in the early and (WHO) [3] revealed that the global dengue cases have middle of the year. The Wards minimum variance method sharply increased from 2.2 million in 2010 to 3.2 million in was able to cluster Selangor’s endemic area into high 2015. Moreover, the organization added that about 2.5% of endemic areas (Gombak, Hulu Langat, Klang and Petaling), the global dengue cases are fatal. There are about 200 medium endemic area (Sepang) and low endemic areas million people in Southeast Asia have been infected with (Hulu Selangor, Kuala Langat, Kuala Selangor, dengue virus [4]. Dengue outbreak is endemic in tropical SabakBernam). The findings of the study are significant to and sub-tropical regions which are mainly driven by respective local authorities in providing information for climatic factors and supported by non-climatic factors. monitoring and planning the early dengue warning systems. This is because the life cycle of Aedes mosquitos is closely This is important to reduce the dengue incidence in hot spot related to climatic factors as it can affect the speed of virus areas and to safeguard the community from dengue replication, the development, survival and dispersal of outbreak. Aedes mosquitos [5-10]. Keywords Dengue Incidence, Spatial and Temporal Spatial and temporal analysis has been widely used in Analysis, Wards Hierarchical Clustering analyzing and detecting the patterns and trends of infectious diseases such as dengue incidence across the underlying time. It is an important analysis prior to other statistical analysis to gain a better understanding on the dengue distribution especially in a specific area so that 1. Introduction early precautions can be well-planned. Besides that, it is Dengue fever is an acute viral infection which is mainly useful to be applied in disease surveillance, epidemiology Universal Journal of Public Health 9(3): 120-130, 2021 121 studies and other studies as this analysis plays an important centroid linkage, median linkage, average linkage and role in quantifying the geographic variation patterns. wards linkage. The study found that out of 6 clustering Broadly speaking, cluster analysis involves methods used, wards method showed better clustering in categorization in which a large group of observations is clustering the dengue cases of various states in India. divided into smaller groups so that the observations within Wards method managed to classify 28 states and 7 union each group are relatively similar (possess similar territories of India into 4 main clusters which were high characteristics) and the observations in different groups are dengue risk, low dengue risk, medium dengue risk and no relatively dissimilar. Cluster analysis is another form of dengue incidence regions. multivariate technique of analysis. This method is Another study was carried out by Ponciano et al. [18] in appropriate to be used if the main intention of the research Guatemala City of 3 main cities (Escuintla, Tiquisate and is to investigate whether or not there are groups of cases in Masagua) using Wards method to cluster the weekly dataset and the characteristics of these groups [11]. The dengue data (2001-2013). A spatial and temporal analysis word ‘cluster’ can also be defined as grouping. It is a class was conducted on climatic variables such as temperature, of techniques used to classify cases into groups that are rainfall and relative humidity. The trend and behavioural of relatively homogeneous within themselves and the climatic variables were observed across time. The heterogeneous between each other, on the basis of a findings obtained based on the spatial and temporal defined set of variables. These groups are called as clusters. analysis revealed that the increased amount of rainfall is Cluster is a group of relatively homogeneous cases or associated to increased dengue incidences in all three observations [12]. In other words, cluster analysis is a localities of Guatemala City. However, temperature and natural grouping of something in common based on humidity were found to be flat for the whole year. Thus, similarities and dissimilarities among objects. rainfall was highlighted as the main variable in causing the According to Johnsonand Wichern [13], the concept of dengue outbreak in Guatemala City. The significant grouping or clustering is different from classification finding from Wards method revealed that the method had method. In classification method, the interest is trying to successfully grouped the dengue data of each localities of identify and observe the classification pattern (form into Guatemala City into 3 major clusters, which roughly can be grouping) due to pre-defined group (existing group). associated to the cases occurred during the warm, rainy and Meanwhile, cluster analysis deals with no assumptions cold seasons. Furthermore, the study also clustered the being made concerning the number of groups or the group health information of Escuintla City and found that there structure. Theoretically, cluster analysis is an exploratory were 2 clusters which can be classified as red alert group technique in which it helps the researcher to explore the (high prevalence of dengue) and yellow alert group (low natural grouping of observations. The concept of grouping prevalence of dengue). or clustering is made on the basis of similarities and Another related work of cluster analysis was done by distances (dissimilarities). Sun et al. [19]. The aim of the study was to examine the Besides that, cluster analysis has been widely used by spatial and temporal trend of dengue and to identify the researchers in many fields of study. For example, it is a epidemic area of Sri Lanka. Sri Lanka consists of 25 popular method in market research field. Since the concept districts. Five-yearly (2012-2016) data on the number of of this analysis is an exploratory technique, it is a dengue cases were collected from Epidemiology Units of preferable method to be used especially in market research. Sri Lanka. The epidemic area of hot spot and cold spot was Cluster analysis works best in market segmentation. For identified using Getis-Ord Gi* statistics. Hot spot area is instance, clustering consumers according to their attribute defined as the area with high dengue transmission while preferences as to observe the impact on buying customer. cold spot is defined as the area with low dengue Cluster is also used in identifying new product transmission. Based on the spatial-temporal clustering opportunities. The clustering of similar brands/products analysis, the hot spot area of Sri Lanka consists of only can help in identifying competitors/market opportunities. Colombo district, while cold spot area includes Ampara, Another reason is that cluster analysis is able to understand Anuradhapura, Badulla, Batticaloa, Kurunegala, Kandy, buying behaviours of the customer. These explain how Kegalle, Matale, Monegarala, Nuwara Eliya, Polonnarwa, important the cluster analysis is needed and why it is Puttalam, Trincomalee and Vavuniya districts. preferable in market research area. Mutheneni et al. [20] studied spatial distribution and Cluster analysis has also been used in epidemic studies cluster analysis of dengue in Andhra Pradesh, India. such as in dengue study [14-20]. A study done by Andhra Pradesh is the third largest and populous state Vandhana and Anuradha [17] employed hierarchical located in India. This state consists of 23 districts. Similar clustering analysis in order to classify the dengue in to a study done by Sun et al. [19], the study was conducted various states of India. The data used in the study consisted to classify the hot spot and cold spot areas of dengue of dengue cases and deaths for 8 years (2011-2018).