In the Philippines, dengue is reported as a leading cause of childhood hospitalisations.1 By September 2011, the disease had already resulted in 285 deaths of children between 1 and 9 years of age2 (Table 1). Fatalities for the 1–9 years-of-age cohort accounted for nearly 60% of deaths due to dengue in 2011, which highlights the importance of early vaccination for young children in endemic regions when a vaccine becomes available.
As a mother and doctor, I have personally experienced the impact that dengue has on the family. When my son contracted dengue, he reached his second day (the critical phase for the risk of haemorrhage) without fever, but still experienced a significantly decreased white blood count and an alarmingly low platelet count. Fortunately, the infection did not result in hypotensive shock or haemorrhage and my son made a full recovery. However, the scenario that unfolded is typical of many families in the Philippines and other dengue endemic areas.
This issue will focus on the epidemiology of dengue in children, current surveillance systems and national efforts to stop mosquitoes from spreading. The introduction of a vaccine will be essential to control the spread of infection that can have devastating consequences in both children and adults.
Edited by Maria Rosario Capeding, MD
Epidemiology: dengue in young children and adolescents
Approximately 36% of annual dengue infections occur among children aged 1–9 years, and the average age of infection is 12 years.2 From January to September 2011, dengue cases in young children and adolescents approached 65,000; 74% of all confirmed cases nationwide (Table 1).
Epidemics of dengue fever and dengue haemorrhagic fever occur every 3–4 years in the Philippines,3 and together with other febrile illnesses in children they impose a considerable burden on the national healthcare system.1 Symptoms such as fever and rash in young children, and fever, severe headache, pain behind the eyes, rash, and muscle and joint pain in adolescents and adults are the more consistent findings;4 and these can lead to costly hospitalisation.
Peak incidence occurs during the wet season in the Philippines (Figure 1) and rainfall correlates significantly to dengue incidence.5 Intensified surveillance and mosquito control efforts during periods of high rainfall are recommended to facilitate the early detection and control of potential outbreaks.5
Dengue surveillance systems
The National Epidemiological Center's (NEC) current surveillance system – Philippine Integrated Disease Surveillance System and Response (PIDSSR) – was implemented in 2007. If the number of cases for a particular region of the country increases, PIDSSR notifies that region of a possible dengue outbreak so that preventive control measures can be implemented.
Figure 2 illustrates the steps from screening suspected patients with dengue to recording and monitoring by national hospitals and the NEC. The surveillance system uses electronic data capture to identify early trends in infection rates and issues alerts. During outbreaks, an active surveillance system is initiated and the NEC coordinates information exchange with local government units. However, identification of possible outbreaks depends on timely reporting from sentinel sites and other hospitals.
Dengue prevention and control initiatives
The National Dengue Prevention and Control Program was established in the late 1990s as a community-based and -managed initiative.7 This included the production of materials, such as leaflets, posters and video tapes, that were translated into 16 local dialects and distributed before the rainy season as a proactive step to prevent the disease.7
Fighting dengue in residential areas and schools
Another government-based initiative, 'Kill the mosquito, Knock out Dengue' or the '4 o'clock habit' requested that residents clean their surroundings and drain water containers to prevent the spread of mosquitoes. Also known as 'operation kaya-kulub (upside down)', the initiative supported the Dengue Control Program and the Malaria Control Program.9,10 As part of this programme, government and private agencies and citizens actively searched, destroyed or eliminated breeding places of mosquitoes at 4 o'clock in the afternoon every day.8
Other initiatives, such as 'The Little Dengue Brigade Program', which started in elementary schools in 199911, have been reactivated in response to increasing reports of dengue cases.12
A unified need for a dengue vaccine
The control or elimination of infection in endemic regions remains a key goal, especially as dengue cases are increasingly being reported.12 While prevention and surveillance efforts address dengue transmission and incidence in the Philippines, there is a greater need for vaccination to combat the disease. Policy-makers, health programme managers, researchers, opinion leaders and other key informants in the Philippines and other Southeast Asian countries have uniformly expressed high-level concern about dengue fever and dengue haemorrhagic fever and the need for a dengue vaccine.14 Studies suggest that conditions are favourable for the introduction of a dengue vaccine in endemic regions.14,15 Of course, it is important to promote vaccine access for children and vulnerable populations at high risk of dengue infection.
Recently a scientific symposium on dengue was held in the Philippines (Figure 4). For the first time, with doctors and media in attendance, the status of a late-stage dengue vaccine was discussed. The meeting reinforced the need for a vaccine and united our commitment to fight and prevent the spread of this disease.
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Writing and editorial support for the first draft of this newsletter was provided by Dr Janki Shah and Julia Davies (Interlace Global Ltd). Dengue v2V and Denguematters is supported by an unrestricted educational grant from sanofi pasteur.
This information is provided for education purposes. The information represents the opinions of the respective experts and authors, which are not necessarily those of sanofi pasteur. Sanofi pasteur and Interlace Global are not responsible for the accuracy or completeness of the information or opinions expressed by the experts or authors/interviewees.