Willingness to pay for control of Aedes aegypti, the dengue virus vector, in Key West, FL and Tucson, AZ

Dengue virus is transmitted by mosquitoes of the genus Aedes; since these mosquitoes breed primarily in stagnant water that collects in human-made containers, a complex interplay between human and environmental factors influences their population dynamics in a given area over time. Over the past several years, both the range of the Aedes mosquito and areas experiencing dengue outbreaks have expanded in the Americas. In 2009 and 2010, a dengue outbreak in Key West, Florida, resulted in 93 confirmed cases, representing the largest outbreak of dengue in the United States since the first half of the twentieth century. Meanwhile, other areas including Tucson, Arizona, have sizable populations of Aedes mosquitoes and are located in close proximity to areas in Mexico where dengue transmission occurs, creating the potential for future outbreaks. In this context, we implemented a household survey in Key West and Tucson that measured willingness to pay for a hypothetical expansion of mosquito control efforts. Respondents were told that this expansion would cut the number of mosquitoes in the local area in half using similar control methods to those already in use by local mosquito control agencies. To fund this expansion, respondents were told that their household and other households in the area would be charged an annual fee. The survey used a triple-bounded dichotomous choice format to assess willingness to pay: all respondents were initially asked if they would support the proposal if the annual fee was set at $100 per year. If the respondent said yes, he or she was asked if they would still support the proposal if the fee were increased to $150, and respondents who said yes to this question were asked if they would still support the proposal if the fee were $200. Respondents who said “no” to the initial $100 fee were asked if they would support the proposal if the fee were lowered to $50; if they said no to this amount, they were asked about their support if the fee were $25. Results allow us to put bounds around respondents' willingness to pay for mosquito control in each city, and to assess relationships between respondent characteristics and willingness to pay in these different disease contexts. Overall, willingness to pay for expanded mosquito control is somewhat higher in Key West compared to Tucson. The proportion of respondents who were not willing to pay any of the proposed fees is roughly equal across the two cities: 26% in Key West compared to 27% in Tucson. However, over half of respondents (51%) in Key West were willing to pay at least $100, compared to 45% in Tucson, and nearly one in five Key West respondents (18%) said that they would be willing to pay $200 (12% in Tucson). Factors associated with higher willingness to pay in both cities included higher levels of education and income. In addition, respondents in both cities who expressed concerns about the environmental impacts of mosquito control were less likely to say that they were willing to pay the highest tax amount ($200). In Key West, respondents were more likely to agree to the highest fee if they knew someone who had had dengue and if they believed current mosquito control efforts were effective. In Tucson, older respondents and respondents with children under five in the household expressed lower willingness to pay amounts, and Latino respondents were less likely to agree to the highest fee. Interestingly, perceived effectiveness of current mosquito control in Tucson was negatively associated with willingness to pay for expanded efforts. Several other variables, including prior awareness of dengue and West Nile virus (also transmitted by mosquitoes) and perceived prevalence of mosquitoes, were not significantly associated with willingness to pay in either city. Results indicate that in two cities with varying mosquito-transmitted disease exposure, the majority of the population would support some increase in publicly-funded mosquito control efforts. In both Tucson and Key West, roughly three quarters of our randomly sampled respondents were willing to pay $25 or more; if a fee of this amount were implemented citywide in both locations, this would amount to an annual budget increase of roughly $625,000 in Key West (population 25,000) and $13 million in Tucson (population 525,000). However, support is not universal in either city, and there is no association between support and the risk or knowledge of disease; therefore, any such expansion would need to be accompanied by significant education and outreach, including providing information on dengue (and other mosquito-borne disease) risk and transmission pathways and addressing concerns about environmental impacts of mosquito control.