Introduction
Dengue fever (DF) is a widespread vector-borne disease that affects millions of people in various parts of the world. In fact, the disease is considered one of the most common vector-borne diseases in the world, which is a health risk to more than 2.5 billion people living in areas prone to infection (Racloz, Ramsey, Tong, Hu 2012). According to World Health Organisation (2012), there are 50 million infection occurrences every year.
Dengue fever virus, a flavivirus that causes DF, has four serotypes denoted as DEN 1-4; all are transmitted by mosquitoes of the species Aedes aegypti (Hoti 2011) and Aedes albopictus (Ran & Raffy 2006). The disease affects thousands of people lying in tropical and subtropical climates where the viruses as well as the vetors thrive (Wu, Guo, Lung, Lin & Su 2007). Sri Lanka has this type of environment, which means that its population is at risk of developing DF (Lipp, Huq & Colwell 2002). In this report, an improved surveillance system for dengue fever in Sri Lanka has been suggested as a probable method for controlling the public health problem.
Epidemiology of Dengue Fever in Sri Lanka
The first national outbreak was observed in 1965, having caused 15 deaths out of 51 cases. Since 1965, the country has experienced several outbreaks (Asia-Pacific Dengue Prevention Board 2007). Major outbreaks have increased in number over the last 15 years (Ministry of Health, Sri Lanka 2013). In 2000, the country reported more than 8900 cases and 64 deaths (World Health Organization 2013a). The cases increased significantly to 15,463 in 2004, but the death rates reduced to 26. Between 2009 and 2010, the country experienced the largest cases of DF of more than 70,000 instances and over 340 deaths.
Objectives of the improved surveillance system for DF in Sri Lanka
The purpose of any surveillance system is to ensure that the capacity of the community to monitor trends of disease and reduce its transmission is enhanced. In fact, the World Health Organization seeks to ensure that the number of member states with adequate surveillance system is increased in order to control the disease development. The WHO encourages countries to develop effective surveillance system and policies in line with its guidelines (Gubler 2004).
In case of Sri Lanka, an improved surveillance system will seek to enhance early detection of the disease in order to ensure that timely interventions are initiated. It aims at ensuring that the surveillance system is aligned to its core and support functions in order to control the spread of the disease and reduce the number of cases and deaths in the future (World Health Organization 2013b).
Secondly, the proposed surveillance system aims at introducing an integrated method surveillance for the vectors (mosquitoes), the DF virus and the environment using Geographical information system, as a part of modern satellite imagery techniques (Chang, Parrales, Jimenez et, al 2009). The purpose is to enhance the identification of the breeding sites for all types of mosquitoes in the country and provide data required to deal with the vector.
Moreover, the improved surveillance system for DF in Sri Lanka aims at providing and enhancing early warning system by increasing the country’s diagnostic capacity. To achieve this, the system will increase Laboratory capacity to enhance performance of case identification and confirmation within a short time, which will ensure that variations of serotype and genetic variations are detected and confirmed in a timely manner (World Health Organization 2012).
Structure and rationale of the enhanced surveillance system for DF
The proposed surveillance system will involve a number of initiatives aimed at reducing the infection cases and deaths in the country. It will use legislation for notification to ensure that private hospitals, traditional physicians and local GPs comply with the public health regulations.
Secondly, it will improve new and standardized data collection and notification methods to ensure that data collection methods also include demographic information on the population affected by the disease. The system will also facilitate collaboration and communication between various parties identified as stakeholders in public health. This will include community-based organizations, local governments, public and private hospitals, medical officers, public health, health inspection unit and epidemiologists.
The system will also ensure that there is a clear and improvised coordination of information sharing and flow across the public health system in order to provide adequate knowledge and information to all the stakeholders. Finally, the system will ensure that all the parties involved cooperate with each other to enhance the implementation of surveillance efforts and documentation of their responsibilities and roles.
Core functions
The functions of the improved system will involve the entire public health sector in Sri Lanka. It will constitute four major core functions: surveillance of the disease, laboratory surveillance, GIS surveillance of the vector and geographical surveillance of the environmental conditions to monitor the progress of DF virus (Gubler, Reiter, Ebi, Yap, Nasci et al 2001). In this context, disease surveillance will include definition of cases with laboratories setup to test all the blood samples taken from the field 3-15 days after the illness is detected in individuals. The system will seek to confirm high proportion of cases to determine the chances of surveillance.
Laboratory surveillance must include enhancement of the country’s laboratory system by setting up additional laboratories in regional centres throughout the country. Laboratory personnel will be required to undergo additional training through workshops to ensure the effectiveness of capacity building. Laboratories will include molecular techniques to identify serotypes and their variations from a genetic perspective.
Evaluation and quality control
The proposed surveillance system will ensure that there is completeness of the report from the local public health units to the central epidemiology unit in Colombo. All the cases identified at the grassroots levels are to be reported to the centre. Secondly, it will ensure a proper time management because local health care facilities will be required to provide case identification to the national centre on time. Moreover, it will ensure there is simplicity of the data collection process, data processing and analysis in addition to information sharing and distribution. Again, this should take the shortest time possible. The new system will be acceptable to all the stakeholders due to its simplicity and applicability. The system will also be flexible because information on diagnosis and laboratory testing is prone to change. The system will provide sensitivity and specificity in order to enhance the ability to detect positive cases on time.
Strengths and weaknesses
The surveillance system has the potential to convince policy makers on the need to initiative an inclusive program that will make all the stakeholders cooperate in the efforts to fight aainst the disease. For instance, it will easily convince the policy makers that the system has the potential to produce positive results. Although it is difficult to achieve this, it is important to set up a pilot study in order to determine some areas of weakness and strength and rework the system to increase its potential.
References
Asia-Pacific Dengue Prevention Board 2007, “Accelerating Progress in Dengue Control: Dengue Surveillance in the Asia-Pacific Region”, Centers for Disease Control and Prevention, Colombo, Sri Lanka.
Chang, A, Parrales, M, Jimenez, J, Sobieszczyk, ME, Hammer,SM, Copenhaver, DJ and Kulkarni, RP 2009, “Combining Google Earth and GIS mapping technologies in a dengue surveillance system for developing countries”, International Journal of Health Geographics, vol. 8, no. 49. Web.
Gubler, DJ 2004, ‘Cities spawn epidemic dengue viruses’, Nature Medicine, vol. 10, no. 2, pp. 129–130.
Gubler, DJ, Reiter, P, Ebi, KL, Yap, W, Nasci, R, & Patz, JA 2001, ‘Climate Variability and Change in the United States: Potential Impacts on Vector- and Rodent-Borne Diseases’, Environmental Health Perspectives Supplements, vol. 109, no. Suppl 2, pp. 223–233.
Hoti, SL 2011, Assessment of epidemiology of dengue in Sri Lanka in relation to intervention measures, Centers for Disease Control and Prevention, Colombo.
Lipp, EK, Huq, A, & Colwell, RR 2002, ‘Effects of global climate on infectious disease: the cholera model’, Clinical Microbiology Reviews, vol. 15, no. 4, pp. 757–770.
Ministry of Health, Sri Lanka, 2013, Weekly Epidemiological Report. Web.
Racloz, V, Ramsey, R, Tong, S, & Hu, W 2012, ‘Surveillance of Dengue Fever Virus: A Review of Epidemiological Models and Early Warning Systems’, Neglected Tropical Diseases, vol.6, no. 5, pp. e1648. Web.
Ran, A & Raffy, M 2006, ‘On the dynamics of dengue epidemics from large-scale information’, Theoretical Population Biology, vol. 69, no. 1, pp. 3–12.
World Health Organisation, 2012, Dengue and severe dengue: Factsheet 117. Web.
World Health Organisation, 2013a, TDR, Dengue. Web.
World Health Organization, 2013b, The dengue strategic plan for the Asia pacific region 2008-2015. Web.
Wu, PC, Guo, HR, Lung, SC, Lin CY & Su, HJ 2007, ‘Weather as an effective predictor for occurrence of dengue fever in Taiwan’, Acta Tropica, vol. 103, no. 1, pp. 50–57.