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82 THIRD WHO REPORT ON NEGLECTED TROPICAL DISEASES
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4.3 Dengue
Introduction
Dengue is a mosquito-borne viral disease of public-health significance that has affected all
regions of WHO since 2010. The flavivirus is transmitted by female mosquitoes mainly
of the species Aedes aegypti and, to a lesser extent, Ae. albopictus.
Investment case
Dengue, a rapidly spreading vector-borne disease, is endemic in more than 100
countries and affects travellers and local communities worldwide. Today, hundreds of
thousands of severe dengue cases arise every year, including about 3000 deaths. The cost of
ambulatory care and hospitalization is unaffordable for poor people. In Cambodia and Viet
Nam, between half and two-thirds of affected households have incurred debt as a result
of treatment. 1,2 The economic burden of the disease is already measured in the billions
of dollars annually. 3,4,5 Environmental change and urbanization are conspiring to elevate
the cost even further beyond the reach of health systems and households. Fortunately,
outbreaks are preventable if detected and managed early. In 2006, the second edition of
the Disease Control Priorities Project put the cost per DALY averted by sustained vector
control at less than US$ 3500 using environmental management and less than US$ 2000
using insecticides. More recent evidence suggests the number might be even lower. 6 (See
the Technical Appendix for further references on cost and cost−effectiveness of vector
control interventions.)
The investment target for sustained vector control is US$ 510 million (US$ 440–580 million)
per year during 2015–2030. This range does not fully reflect uncertainty about the size and
distribution of the population at risk, especially in Africa. It probably underestimates the
cost of sustained vector control for all populations at risk. Nonetheless, these conservative
estimates indicate that vector control will be of increasing importance within the NTD
portfolio. The investments are significant, but less than the costs of the alternatives. A
review of the literature suggests that the cost of sustained vector control is lower than that
of outbreak response. 7
The introduction of a highly effective vaccine against dengue may re-programme some of
the investments in vector control towards immunization but is unlikely to obviate the need
for it. The available models suggests that vector control will remain cost−effective in the
presence of a vaccine. 8,9,10 Vector control may enhance the cost−effectiveness of a mediumefficacy
vaccine, or a vaccine that is highly effective but only against one of the four dengue