2012 Annual Report
Economic cost of vector control: to estimate the economic cost of vector control, the Brandeis team collected budget documents and interviewed program officials regarding Asian Tiger Mosquito (ATM) surveillance and prevention activities from Monmouth and Mercer counties and Rutgers University. The team members then tabulated and analyzed the data to break down the cost of ATM for the years 2007, 2008, 2009, 2010 and 2011 by type of activity (routine or area wide pest management (AWPM)--project related), function and intervention area. Functions include: control adulticiding, control larviciding and control source reduction, surveillance, ATM research, non-ATM research, and education. The initial full intervention areas were South Olden in Mercer and Cliffwood Beach in Monmouth (shifted to control area in 2011). The second intervention areas were South Clinton in Mercer and North Middletown in Monmouth. The initial control areas were Cumming in Mercer and Union Beach in Monmouth (shifted to full intervention in 2011). The cost of the educational intervention implemented by Rutgers University was estimated for the years 2008 through 2011 by line item and intervention areas. The overall economic cost of ATM in the full intervention areas for the year 2011 was $23.53 per capita (98.5% due to AWPM project activities and 1.5% due to routine county activities), compared to $6.55 per capita in the control areas (94.9% due to AWPM project activities beginning in 2011 and 5.1% due to routine county activities). Further analyses will be conducted to estimate the economic cost of favorable interventions. A costing tool for these interventions is under development. Household surveys: Four annual rounds of household surveys were conducted in the six selected study sites in the years of 2008 through 2011. The focus of these surveys was to understand how mosquitoes affect households’ mosquito-related expenditures, quality of life and engagement in outdoor activities. Two willingness-to-pay surveys were conducted: the first (phone interview) was implemented in 2008 focusing on residents’ willingness-to-pay for an effective vector program to reduce the nuisance associated with urban mosquitoes including ATM. A manuscript based on this work was accepted for publication in the Journal of the American Mosquito Control Association. The second (face-to-face interview) was conducted in 2010 for 120 households in the six study sites. These interviews focused on residents’ willingness-to-pay for one additional free-of-mosquitoes hour engaged in yard or porch activities. Random samples of households in AWPM and control areas were surveyed each fall since 2008 by a self-administered mail survey. Hours lost due to mosquitoes were calculated as differences between actual hours engaged in yard and porch activities in an average summer week, and the potential hours the respondent would have spent engaged in yard and porch activities, if there was no mosquito concern.
We conducted the analyses of the household surveys in the baseline year, 2008, with 310 households, and second intervention year, 2010, with 396 households in AWPM and control areas combined. We measured changes in hours spent outdoors and in mitigation expenditures (e.g., repellents purchased) from 2008 to 2010 in AWPM areas and compared results with corresponding changes in control areas. The average proportion of potential outdoor hours lost due to mosquitoes in intervention areas decreased (±SEM) from 29.7%±2.6% in 2008 to 24.3%±2.1% in 2010. Findings showed a net improvement of 7.0%±4.3% or additional 1.89±1.9 hours spent in porch or yard activities due to AWPM (p=0.10). The share of residents bothered by mosquitoes in the full intervention AWPM area decreased from 68.6% in 2008 to 46.0% in 2010, indicating a net reduction in the nuisance from mosquitoes of 11.6% (p=0.11). The project has been effective in reducing the nuisance caused by urban mosquitoes and increased both knowledge and yard and porch activities.
Net estimated economic benefits of AWPM were based on a difference-in-difference analysis (between years and areas). Reductions in hours lost were valued based on respondents’ willingness-to-pay (WTP) for a hypothetical extra hour free of mosquitoes that they could spend in yard or porch activities. Numbers of hours lost per week due to mosquitoes in AWPM areas between the base year (2008) and the second intervention year 2010 declined (mean±SEM) by 1.88±4.19 hours per person per week in intervention areas compared to control areas. While not statistically significant, the pattern suggests potential program effectiveness. The control program’s average per capita expenditure on ATM (2009, 2010 and 2011) in the full intervention areas was $35.9 per capita per year. This results in a net benefit per resident of $12.9 per year (range: -$11.5 to $37.41) and a benefit-cost ratio of 1.36 (range: 0.68-2.04). The program had a favorable behavioral impact. The benefit-cost analysis of data to date suggests a positive net benefit of the AWPM from residents being able to enjoy more time on porches and yards. These analyses are being continued with the latest survey results obtained in late 2011.