Epidemiology of dengue disease in the Philippines (2000-2011): a systematic literature review

Abstract

This literature analysis describes the available dengue epidemiology data in the Philippines between 2000 and 2011. Of 253 relevant data sources identified, 34, including additional epidemiology data provided by the National Epidemiology Center, Department of Health, Philippines, were reviewed. There were 14 publications in peer reviewed journals, and 17 surveillance reports/sources, which provided variable information from the passive reporting system and show broad trends in dengue incidence, including age group predominance and disease severity. The peer reviewed studies focused on clinical severity of cases, some revealed data on circulating serotypes and genotypes and on the seroepidemiology of dengue including incidence rates for infection and apparent disease. Gaps in the data were identified, and include the absence incidence rates stratified by age, dengue serotype and genotype distribution, disease severity data, sex distribution data, and seroprevalence data.

Figure 1. Map of the Philippines showing the administrative 17 regions , .

The Republic of the Philippines is an archipelago in Southeast Asia consisting of 7107 islands. The country is divided into 17 regions within the three island groups of Luzon (Regions I–V, Cordillera Administrative Region [CAR] and National Capital Region [NCR]), Visayas (Regions VI–VIII) and Mindanao (Regions IX–XIII and Autonomous Region in Muslim Mindanao). Metro Manila is the metropolitan area that contains the City of Manila, the capital of the Philippines. The metropolis is officially called the National Capital Region (NCR, the term used throughout this report) and is composed of Manila plus 16 neighboring cities and municipalities, including Quezon City.

Figure 2. Results of literature search and evaluation of identified studies according to PRISMA.

All references identified in the on-line database searches were assigned a unique identification number. Following the removal of duplicates and articles that did not satisfy the inclusion criteria from review of the titles and abstracts, the full papers of the first selection of references were retrieved either electronically or in paper form. A further selection was made based on review of the full text of the articles. DoH, Department of Health; EMBASE, Excerpta Medica Database; IMSEAR, Index Medicus for South East-Asia Region; Medline, United States National Library of Medicine and the National Institutes of Health Medical Database; PRISMA, preferred reporting items of systematic reviews and meta-analyses; WHOLIS, World Health Organization Library database; WHOSEAR, World Health Organization Regional Office for Southeast Asia; WPRO, World Health Organization Western Pacific Region.

Figure 3. The epidemiology of dengue disease in the Philippines, 2000–2011.

A: The number of reported dengue disease cases and incidence per 100,000 population. B: The number of reported deaths attributed to dengue disease and CFR per 100 cases. The reported number of dengue disease cases in the Philippines fluctuated throughout the review period, with an overall increase in incidence observed over time. Peaks in dengue disease cases occurred in 2001, 2003 and 2007. Dengue disease-related deaths fluctuated, peaking in 2006. Overall, the CFR was in the range 0.5–1.2 per 100 cases and decreased after 2005. Using available data* from the DoH , – and the WHO , , , , –. Sources: Number of reported cases: 2000–2005: DoH 2000–2005 ; 2006–2007: FHSIS 2000–2009 ; 2008–2011: WHO data: WHO 2008 , 2009 , 2012 , (2010 and 2011 values estimated from graph); Incidence: 2000–2007: FHSIS 2000–2009 ; Deaths: 2000–2005: DoH 2000–2005 ; 2006: DoH 2011 ; 2007–2010: Arima and Matsuia 2011 ; 2011: WHO 2012 (value estimated from graph); CFR: 2000–2005: WHO 2008 ; 2006–2010: Arima and Matsuia 2011 ; 2011: WHO 2012 (value estimated from graph). *Data on all dengue disease cases were not publically available from the DoH between 2008 and 2011. CFR, case fatality rate; DoH, Department of Health; WHO, World Health Organization.

Figure 4. Dengue virus serotype distribution in the Philippines: regional studies.

All four DENV serotypes were reportedly present in the Philippines at some time during the review period – but the predominant serotypes changed from DENV-1 and -2 early in the review period , , to DENV-3 towards the end of the review period –, .