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Geospatial Health 2021; volume 16:957 Use of geographic information system as a tool for schistosomiasis surveillance in an endemic Municipality in Eastern Samar, The Philippines Vicente Y. Belizario, Jr.,1,2 John Paul Caesar R. delos Trinos,2,3 Nestor Lentejas,4 Allen J. Alonte,2 Agnes N. Cuayzon,5 Marian E. Isiderio,6 Rodel Delgado,6 Marilou Tejero,7 Victorio B. Molina1 1College of Public Health, University of the Philippines Manila, Manila, Philippines; 2Neglected Tropical Diseases Study Group, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; 3Kirby Institute, University of New South Wales Sydney, Sydney, Australia; 4Plan International Philippines, Makati, Philippines; 5Department of Health Centre for Health Development, Eastern Visayas, Philippines; 6Provincial Health Office, Eastern Samar, Philippines; 7Municipal Health Office, Oras, Eastern Samar, Philippines modifiable (geography and climate) determinants for schistosomi- Abstract asis. Results showed that most barangays (villages) are character- This study aimed to demonstrate the use of geographic infor- ized by favourable conditions for schistosomiasis transmission mation systems (GIS) in identifying factors contributing to schis- which include being located in flood-prone areas, presence of tosomiasis endemicity and identifying high-risk areas in a schisto- vegetation, low sanitaryonly toilet coverage, presence of snail interme- somiasis-endemic municipality in the Philippines, which was dev- diate host, high carabao (water buffalo) population density, previ- astated by Typhoon Haiyan in 2013. Data on schistosomiasis ously reported ≥1% prevalence using Kato-Katz technique, and determinants, obtained through literature review, the Philippine low MDA coverage. Similarly, barangays not known to be endem- Department of Health, and concerned local government units, ic for schistosomiasisuse but also characterized by the same were standardized and incorporated into a GIS map using ArcGIS. favourable conditions for schistosomiasis as listed above and may Data gathered included modifiable [agriculture, poverty, sanita- therefore be considered as potentially endemic, even if not being tion, presence of intermediate and reservoir hosts, disease preva- high-risk areas. This study demonstrated the importance of GIS lence and mass drug administration (MDA) coverage] and non- technology in characterizing schistosomiasis transmission. Maps generated through application of GIS technology are useful in guiding program policy and planning at the local level for an effective and sustainable schistosomiasis control and prevention. Correspondence: Vicente Y. Belizario, Jr., College of Public Health, University of the Philippines Manila, 625 Pedro Gil St., Ermita, Manila, 1000 Metro Manila, the Philippines. Tel.: +632.523.5929 – loc. 142. E-mail: [email protected] Introduction Key words: Schistosomiasis; geographic information systems; surveil- Schistosomiasis, caused by the blood fluke Schistosoma spp., lance; Eastern Samar; the Philippines; war on worms; nutrition; water; is a debilitating and potentially fatal neglected tropical disease sanitation; hygiene. (NTD) affecting about 240 million people according to the World Health Organization (WHO, 2020). It persists in areas where Acknowledgements: the researchers would like to acknowledge the access to adequate sanitation and hygiene is limited, and remains partner institutions, such as PlanNon-commercial International Philippines, DOH RO a public health concern in low- and middle-income countries such VIII, Eastern Samar provincial LGU, and Oras municipal LGU, as well as the Philippines. Transmission occurs through skin penetration as Ms. Lynnell Alexie D. Ong, for their valuable contributions which made this study possible. The researchers would also like to thank by infective cercariae released by the intermediate snail host United States Agency for International Development and RTI Oncomelania hupensis quadrasi during contact with contaminated International for providing research funds. waters (WHO, 2020). It is associated with morbidities such as under-nutrition, impaired cognitive processes, decreased work Received for publication: 15 November 2020. productivity and chronic abdominal or pelvic pain (King et al., Revision received: 2 March 2021. 2005). WHO aims to eliminate schistosomiasis by 2030 as a pub- Accepted for publication: 3 March 2021. lic health problem, defined as reducing prevalence of heavy inten- sity infections to <1% (WHO, 2020). ©Copyright: the Author(s), 2021 In the Philippines, schistosomiasis, caused by S. japonicum, Licensee PAGEPress, Italy Geospatial Health 2021; 16:957 remains endemic and according to the Philippine Department of doi:10.4081/gh.2021.957 Health (DOH) 189 municipalities and 15 cities in 28 provinces are infected, with approximately 2.5 million people at risk for the This article is distributed under the terms of the Creative Commons infection (DOH, 2018). The local government units (LGUs) in Attribution Noncommercial License (CC BY-NC 4.0) which permits any collaboration with DOH, through the Schistosomiasis Control and noncommercial use, distribution, and reproduction in any medium, pro- Elimination Program, implements community-based mass drug vided the original author(s) and source are credited. administration (MDA) of praziquantel every January as a key [Geospatial Health 2021; 16:957] [page 213] Article strategy for schistosomiasis morbidity control (DOH, 2007; 2016). province, GIS was also used to determine the relationship of vari- Other strategies include case-finding and management; promotion ous schistosomiasis determinants which may contribute to trans- of veterinary public health; snail control and surveillance; and mission of the infection (Belizario et al., 2017). These studies improvements in water and sanitation facilities in all endemic exemplified very well how to visualize the factors contributing to areas (DOH, 2018). Pockets of high endemicity, however, are still schistosomiasis through GIS maps. observed despite a decade of program implementation (DOH, The War-on-Worms, the Nutrition, Water, Sanitation, and 2018). Among these is the Eastern Samar Province, which remains Hygiene Project led by the University of the Philippines in Manila endemic for schistosomiasis with a prevalence of 4.3% in school- in partnership with Plan International Philippines, investigated the age children according to the regional office of the DOH (DOH status of schistosomiasis in Eastern Visayas (a major group of RO VIII, 2016). In November 2013, the strongest typhoon islands in the Philippines) after Typhoon Haiyan. As part of the (Haiyan) to ever hit the Philippines, devastated the province and project, this study aimed to demonstrate the use of GIS in identify- posed challenges in schistosomiasis control as it disrupted the local ing factors contributing to schistosomiasis endemicity and high- health service delivery and compromised access to safe water and risk areas in an endemic and Haiyan-stricken municipality in sanitation (United Nations Children’s Fund, 2015; Salazar et al., Eastern Samar, one of the provinces in Visayas. 2017). Inadequate water supply, limited access to sanitation facili- ties and poor hygiene practices are major contributing factors to the spread of schistosomiasis (Kouadio et al., 2012). Surveillance is needed to assess the status of schistosomiasis Materials and methods and identify the needed interventions for effective infection con- trol. The WHO recommends mapping of endemicity as part of Study location surveillance to allow identification of high-risk areas for the infec- tion, which allows implementation of targeted delivery of services, Eastern Samar, a provinceonly in the Eastern Visayas region, is especially when resources are limited (WHO, 2020). composed of 23 municipalities (Philippine Statistics Authority, The utility of geographic information systems (GIS), a com- 2015), ten of which are known to be endemic for schistosomiasis puter-based tool designed to integrate, analyse, and visualize spa- (DOH, 2009). Schistosomiasis prevalence in the province is 4.3% tial information (Higgs, 2004), in mapping schistosomiasis in school-age childrenuse (DOH RO VIII, 2016). Oras, a low income endemicity has been demonstrated in several studies. It has been municipality, was selected as the study site due to its known effectively used in Anhui Province in China to identify high-risk endemicity for the infection with 25 out of 42 barangays (villages) areas and possible transmission of schistosomiasis in other areas known to be schistosomiasis-endemic (DOH RO VIII, 2016) (Hu et al., 2015). In the Philippines, GIS together with remote (Figure 1). This selection was based on availability of data on fac- sensing was used to demonstrate how land use and topography tors contributing to schistosomiasis endemicity as well as active affect spatial distribution of malaria and schistosomiasis in the participation of and partnership with local stakeholders, such as the province of Davao del Norte (Leonardo et al., 2005). In the same DOH and LGUs, could be counted on. Non-commercial Figure 1. Map of the Philippines (left) and Eastern Samar Province (right) with the Oras Municipality. [page 214] [Geospatial Health 2021; 16:957] Article Data collection and processing Barangays with open defecation areas; ii) Grade 1 barangays, A literature review was conducted to identify the determinants which have zero open defecation (ZOD)