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IntroductionDengue is a rapidly emerging vector-borne Neglected Tropical Disease, with a 30-fold increase in the number of cases reported since 1960. The economic cost of the illness is measured in the billions of dollars annually. Environmental change and unplanned urbanization are conspiring to raise the health and economic cost even further beyond the reach of health systems and households. The health-sector response has depended in large part on control of the Aedes aegypti and Ae. albopictus (mosquito) vectors. The cost-effectiveness of the first-ever dengue vaccine remains to be evaluated in the field. In this paper, we examine how it might affect the cost-effectiveness of sustained vector control.MethodsWe employ a dynamic Markov model of the effects of vector control on dengue in both vectors and humans over a 15-year period, in six countries: Brazil, Columbia, Malaysia, Mexico, the Philippines, and Thailand. We evaluate the cost (direct medical costs and control programme costs) and cost-effectiveness of sustained vector control, outbreak response and/or medical case management, in the presence of a (hypothetical) highly targeted and low cost immunization strategy using a (non-hypothetical) medium-efficacy vaccine.ResultsSustained vector control using existing technologies would cost little more than outbreak response, given the associated costs of medical case management. If sustained use of existing or upcoming technologies (of similar price) reduce vector populations by 70–90%, the cost per disability-adjusted life year averted is 2013 US$ 679–1331 (best estimates) relative to no intervention. Sustained vector control could be highly cost-effective even with less effective technologies (50–70% reduction in vector populations) and in the presence of a highly targeted and low cost immunization strategy using a medium-efficacy vaccine.DiscussionEconomic evaluation of the first-ever dengue vaccine is ongoing. However, even under very optimistic assumptions about a highly targeted and low cost immunization strategy, our results suggest that sustained vector control will continue to play an important role in mitigating the impact of environmental change and urbanization on human health. If additional benefits for the control of other Aedes borne diseases, such as Chikungunya, yellow fever and Zika fever are taken into account, the investment case is even stronger. High-burden endemic countries should proceed to map populations to be covered by sustained vector control.

In response to worker and union representative concerns, the association between metalworking fluid exposure and respiratory symptoms was investigated in a cross-sectional survey, in a large automotive machining location. A self-administered respiratory symptom-screening questionnaire was sent to 2935 current employees. MWF exposure levels were assigned to respondents on a departmental basis based on average and "peak" area aerosol measurements. MWF exposure, years in the plant, and smoking status were regressed on presence or absence of daily or weekly respiratory symptoms, as well as upper and lower respiratory symptom groupings derived from principal components factor analysis. The response rate was 81 percent. Symptom prevalence was high: 29 percent of subjects reported weekly or daily phlegm; 23 percent, dry cough; 42 percent, runny or plugged nose. Average aerosol concentration in departments with exposure ranged from 0.02 to 0.84 mg/m(3), and peak levels from 0.02 to 2.85 mg/m(3). Average exposures ranging from 0.25 to 0.84 mg/m(3), as compared to exposures in the range of 0.02 to 0.09 mg/m(3), were statistically significantly associated with wheezing, chest tightness, sore throat, and hoarse throat, as well as with the upper respiratory symptom grouping. When peak exposure was included in the regression, it exerted a stronger effect than average exposure level on dry cough, phlegm, wheezing, fever/chills, and hoarse throat, as well as on upper and lower respiratory symptom groupings. These effects were independent of smoking status. Exposure-symptom trends for the average and peak departmental area concentration categories were statistically significant for the upper and lower respiratory symptom groupings and for most individual symptoms. We have observed an association of increasing upper and lower respiratory symptoms with estimated MWF exposure, measured independently, at average departmental aerosol concentrations well below the NIOSH recommended personal exposure level of 0.5 mg/m(3). The results have been used to prioritize exposure reduction efforts in the workplace.

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