Amer Jnl Trop Med & Hyg, May 2012
The Economic Burden of Dengue
Duane J. Gubler.
In 2012, dengue is the most important vector-borne viral disease of humans and likely more important than malaria globally in terms of morbidity and economic impact. The latest studies estimate 3.6 billion people living in areas of risk, over 230 million infections, millions of cases of dengue fever, over 2 million cases of the severe disease, and 21,000 deaths.
In addition to the public health and economic costs, there is a major social impact in those countries where large epidemics occur, often disrupting primary care for hospitalized patients. Given the dramatic urban growth and lack of adequate surveillance for dengue in tropical developing countries in the past 50 years, it is likely that even these figures underestimate the true disease burden of dengue.
The Primary Health Care Approach to Dengue Prevention and Control, 2011. WHO/SEARO.
The ultimate goal of controlling any epidemic disease including dengue is to prevent its transmission and contain the spread of the disease as soon as possible. The success of the efforts for prevention and control of dengue relies on the effectiveness of the initiatives to control the breeding sites of the vector by improving public and household environmental sanitation and water supply, and through sustained modification of human behaviour.
This requires the entire gamut of public health activities, namely, health promotion, which is the process of enabling people across all socioeconomic groups to increase control over, and to improve, their health; and disease prevention and treatment with appropriate technology along with rehabilitation. However, efforts to prevent and control dengue in the past have been constrained due to inadequate community participation as well as lack of the necessary degree of intersectoral cooperation and service coverage, which are the core elements of PHC.
Understanding dengue transmission by using participatory research and community-focused strategies for prevention and control in Bangladesh. BMC Infect Dis. May 2012; 12(Suppl 1): P92.
Parnali Dhar Chowdhury, et al.
Background – Globally, dengue has become one of the most alarming infectious diseases and its resurgence reflects the failure of traditional reductionistic disciplinary approach. Because neither an effective vaccine nor an effective vector control program is available for dengue prevention and control, a Community-Based Approach (CBA) to vector control and individual behavior change has been implemented in many countries. However, by and large, the CBA has failed as it ignored local community members’ basic needs and perspectives in these processes. By challenging reductionist notions, this research will delineate the mental maps of local urban residents of the City of Dhaka, Bangladesh concerning dengue transmission and methods of dengue prevention and control.
Methods – This study involved focus group discussion in 3 wards of Dhaka City Corporation, semi-structured interview of 30 stakeholders representatives; 900 ward/community members (300 from each ward); 18 policy- and/or decision makers (national and local institutions) and community members’ mental map construction of 24 ward representatives (supplemented by 300 ward members).
Results – This study revealed the lack of intersectoral coordination between local and national institutions dealing with disease and household sanitation, and highlights the difficulties in avoiding dengue vectors in urban areas with irregular water supply, poor sanitation services, and finally the location of large and small construction zones all over the city.
Conclusion – The conclusion emphasizes the importance of the knowledge about the daily problems faced by the community members and partnership needed in all sectors to address water supply problem and disease surveillance systems.
Dengue, Urbanization and Globalization: The Unholy Trinity of the 21(st) Century. Trop Med Health. 2011 Dec;39(4 Suppl):3-11.
Gubler DJ. Professor and Director, Signature Research Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857.
Dengue is the most important arboviral disease of humans with over half of the world’s population living in areas of risk. The frequency and magnitude of epidemic dengue have increased dramatically in the past 40 years as the viruses and the mosquito vectors have both expanded geographically in the tropical regions of the world. There are many factors that have contributed to this emergence of epidemic dengue, but only three have been the principal drivers:
- 1) urbanization,
- 2) globalization and
- 3) lack of effective mosquito control.
The dengue viruses have fully adapted to a human-Aedes aegypti-human transmission cycle, in the large urban centers of the tropics, where crowded human populations live in intimate association with equally large mosquito populations. This setting provides the ideal home for maintenance of the viruses and the periodic generation of epidemic strains. These cities all have modern airports through which 10s of millions of passengers pass each year, providing the ideal mechanism for transportation of viruses to new cities, regions and continents where there is little or no effective mosquito control. The result is epidemic dengue. This paper discusses this unholy trinity of drivers, along with disease burden, prevention and control and prospects for the future.
Dengue vector control strategies in an urban setting: an economic modelling assessment. Lancet, 377 (9778), 2011. Luz, PM; Vanni, T; Medlock, J; Paltiel, AD; Galvani, AP.
Background – An estimated 2.5 billion people are at risk of dengue. Incidence of dengue is especially high in resource-constrained countries, where control relies mainly on insecticides targeted at larval or adult mosquitoes. We did epidemiological and economic assessments of different vector control strategies.
Methods – We developed a dynamic model of dengue transmission that assesses the evolution of insecticide resistance and immunity in the human population, thus allowing for long-term evolutionary and immunological effects of decreased dengue transmission. We measured the dengue health burden in terms of disability-adjusted life-years (DALYs) lost. We did a cost-effectiveness analysis of 43 insecticide-based vector control strategies, including strategies targeted at adult and larval stages, at varying efficacies (high-efficacy [90% mortality], medium-efficacy [60% mortality], and low-efficacy [30% mortality]) and yearly application frequencies (one to six applications). To assess the effect of parameter uncertainty on the results, we did a probabilistic sensitivity analysis and a threshold analysis.
Findings – All interventions caused the emergence of insecticide resistance, which, with the loss of herd immunity, will increase the magnitude of future dengue epidemics. In our model, one or more applications of high-efficacy larval control reduced dengue burden for up to 2 years, whereas three or more applications of adult vector control reduced dengue burden for up to 4 years. The incremental cost-effectiveness ratios of the strategies for two high-efficacy adult vector control applications per year was US$615 per DALY saved and for six high-efficacy adult vector control applications per year was $1267 per DALY saved. Sensitivity analysis showed that if the cost of adult control was more than 8.2 times the cost of larval control then all strategies based on adult control became dominated.
Interpretation – Six high-efficacy adult vector control applications per year has a cost-effectiveness ratio that will probably meet WHO’s standard for a cost-effective or very cost-effective intervention. Year-round larval control can be counterproductive, exacerbating epidemics in later years because of evolution of insecticide resistance and loss of herd immunity. We suggest the reassessment of vector control policies that are based on larval control only.
Dengue and severe dengue Fact Sheet, January 2012. World Health Organization.
Key facts
- Dengue is a mosquito-borne viral infection.
- The infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue.
- The global incidence of dengue has grown dramatically in recent decades.
- About half of the world’s population is now at risk.
- Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
- Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries.
- There is no specific treatment for dengue/ severe dengue, but early detection and access to proper medical care lowers fatality rates below 1%.
- Dengue prevention and control solely depends on effective vector control measures.
Dengue is a mosquito-borne infection found in tropical and sub-tropical regions around the world. In recent years, transmission has increased predominantly in urban and semi-urban areas and has become a major international public health concern.
Source: WHO/TDR
Severe dengue (previously known as Dengue Haemorrhagic Fever) was first recognized in the 1950s during dengue epidemics in the Philippines and Thailand. Today, severe dengue affects most Asian and Latin American countries and has become a leading cause of hospitalization and death among children in these regions.
There are four distinct, but closely related, serotypes of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4). Recovery from infection by one provides lifelong immunity against that particular serotype. However, cross-immunity to the other serotypes after recovery is only partial and temporary. Subsequent infections by other serotypes increase the risk of developing severe dengue.
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The portal is an activity of the Promoting Integrated Sustainable Waste Management through Public Private Partnerships (PPP-ISWM) programme, in short. The Programme is jointly implemented by the UNDP Public Private Partnerships Programme (UNDP PPPSD) and WASTE, a Netherlands-based NGO.
Web site: wasteportal.net
International Scholarly Research Network, ISRN Soil Science, 2012
Faecal Blending for Nutrient Enrichment and Speedy Sanitisation for Soil Fertility Improvement
F. Ogwang, et al.
Human faeces have been used for soil fertility improvement over time, but limited information is available on the value of this resource in Africa. The fear of the pathogenicity of the material hinders the realisation of its potential value in agriculture. A study was conducted at Makerere University Agricultural Research Institute, Kabanyolo in Uganda, to investigate the sanitising potential and nutrient enrichment capabilities of animal wastes on human faeces from Ecological Sanitation (EcoSan) toilets. Treatments included EcoSan human faeces (EHF) blended with either poultry manure (PM) or cattle manure (CM) mixed in the ratios of 1 : 1 (dry weight basis), before the mixtures were composted. The layout consisted of fifteen wooden composting boxes of 1m−3 dimensions, laid above ground. Each box was lined with 1.5m3 1000um polythene. Poultry manure and its blend with EHF enhanced high temperature and concentrations of plant nutrients. Human faeces alone had meagre nutrients concentrations, but high K+. The high K+ was possibly due to inclusion of kitchen ash in the EcoSan toilets. Among the blended treatments, EHF + PM and EHF + CM achieved 100 and 75% sanitisation of E. coli and Enterococcus species, respectively.
What are the effects of different models of delivery for improving maternal and infant health outcomes for poor people in urban areas in low income and lower middle income countries?
Coast, Ernestina and McDaid, David and Leone, Tiziana and Pitchforth, E. and Matthews, Zoe and Iemmi, Valentina and Hirose, Atsumi and Macrae-Gibson, Rowena and Secker, Jane and Jones, Eleri (2012). Department for International Development, London.
Our analyses form a convincing case that there is a need for high-quality evidence on maternal and infant interventions that specifically target the urban poor. The existing evidence base is minuscule compared to the rapidly growing and large urban poor population. Much of the existing evidence is of poor quality, with little emphasis on baselines and follow-up studies, and almost no qualitative (how? why?) evidence to complement the limited quantitative (what?) data. This small evidence base is out of step with the growing interest in urban poor people and the size of this population. Interventions supported by the review are already present in existing WHO guidelines. However, there is a need for research that specifically addresses the effectiveness of different models of service delivery, including how sub-populations (e.g., urban poor) are targeted.
International Journal for Equity in Health 2012, 11:15
Taking action on the social determinants of health: improving health access for the urban poor in Mongolia
Khandsuren Lhamsuren, et al.
Introduction – In recent years, the country of Mongolia (population 2.8 million) has experienced rapid social changes associated with economic growth, persisting socio-economic inequities and internal migration. In order to improve health access for the urban poor, the Ministry of Health developed a “Reaching Every District” strategy (RED strategy) to deliver an integrated package of key health and social services. The aim of this article is to present findings of an assessment of the implementation of the RED strategy, and, on the basis of this assessment, articulate lessons learned for equitable urban health planning.
Methods – Principal methods for data collection and analysis included literature review, barrier analysis of health access and in-depth interviews and group discussions with health managers and providers.
Findings – The main barriers to health access for the urban poor relate to interacting effects of poverty, unhealthy daily living environments, social vulnerability and isolation. Implementation of the RED strategy has resulted in increased health access for the urban poor, as demonstrated by health staff having reached new clients with immunization, family planning and ante-natal care services, and increased civil registrations which enable social service provision. Organizational effects have included improved partnerships for health and increased motivation of the health workforce. Important lessons learned from the early implementation of the RED strategy include the need to form strong partnerships among stakeholders at each level of the health system and in the community, as well as the need to develop a specific financing strategy to address the needs of the very poor. The diverse social context for health in an urban poor setting calls for a decentralized planning and partnership strategy, but with central level commitment towards policy guidance and financing of pro-poor urban health strategies.
Conclusions – Lessons from Mongolia mirror other international studies which point to the need to measure and take action on the social determinants of health at the local area level in order to adequately reduce persistent inequities in health care access for the urban poor.
