Unforeseen Costs of Cutting Mosquito Surveillance Budgets

Kitron U (2010) Unforeseen Costs of Cutting Mosquito Surveillance Budgets. PLoS Negl Trop Dis 4(10): e858. doi:10.1371/journal.pntd.0000858 Unforeseen Costs of Cutting Mosquito Surveillance Budgets Gonzalo M. Vazquez-Prokopec 0 Luis F. Chaves 0 Scott A. Ritchie 0 Joe Davis 0 Uriel Kitron 0 Ann M. Powers, Centers for Disease Control and Prevention, United States of America 0 1 Department of Environmental Studies, Emory University , Atlanta , Georgia , United States of America, 2 Programa de Investigacio n en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional , Heredia , Costa Rica , 3 Cairns Tropical Public Health Unit, Queensland Health , Cairns, Queensland , Australia , 4 School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University , Cairns, Queensland , Australia A budget proposal to stop the U.S. Centers for Disease Control and Prevention (CDC) funding in surveillance and research for mosquito-borne diseases such as dengue and West Nile virus has the potential to leave the country illprepared to handle new emerging diseases and manage existing ones. In order to demonstrate the consequences of such a measure, if implemented, we evaluated the impact of delayed control responses to dengue epidemics (a likely scenario emerging from the proposed CDC budget cut) in an economically developed urban environment. We used a mathematical model to generate hypothetical scenarios of delayed response to a dengue introduction (a consequence of halted mosquito surveillance) in the City of Cairns, Queensland, Australia. We then coupled the results of such a model with mosquito surveillance and case management costs to estimate the cumulative costs of each response scenario. Our study shows that halting mosquito surveillance can increase the management costs of epidemics by up to an order of magnitude in comparison to a strategy with sustained surveillance and early case detection. Our analysis shows that the total costs of preparedness through surveillance are far lower than the ones needed to respond to the introduction of vector-borne pathogens, even without consideration of the cost in human lives and well-being. More specifically, our findings provide a science-based justification for the re-assessment of the current proposal to slash the budget of the CDC vector-borne diseases program, and emphasize the need for improved and sustainable systems for vector-borne disease surveillance. - Funding: This work was supported by Emory University (Department of Environmental Studies internal support). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. The 2011 U.S. fiscal year proposed budget cut of $26.7 million from the CDC vector-borne diseases program [1] could virtually paralyze surveillance and research activities directed at diseases already circulating in the U.S such as dengue and West Nile virus (WNV), and jeopardize the capability of the existing health infrastructure for early detection of other exotic mosquito-transmitted pathogens such as Rift Valley fever, Japanese encephalitis and chikungunya virus [1]. Surveillance is the first line of defense against infectious diseases [2], guides health agencies response to infectious threats, optimizes resources by focusing interventions on target areas, and generates invaluable information for health providers and policy makers [2]. We present here a case study where we couple a mathematical model with cost analysis to evaluate the economic impact of different response scenarios to the introduction of a vector-transmitted pathogen of public health importance into an economically developed urban environment. Data from two well-documented and successfully controlled dengue fever outbreaks introduced by viremic travelers into the city of Cairns, Queensland, Australia in 2003 and 2009 [3,4] were used to derive the basic reproductive number (R0) and the effective reproduction number (Rt) of dengue transmission. R0 represent the average number of secondary cases after the introduction of an infection, and was estimated by fitting an exponential function to the observed weekly epidemic curves before vector control interventions began (6 weeks in 2003 and 4 weeks in 2009, Figure 1 AB) following the method of Nishiura et al. [5]. Rt represent the average number of secondary cases per primary case at time t of each outbreak and was estimated by accumulating the number of cases in biweekly periods (the average generation time of dengue is ,14 days) and computing the ratio between consecutive two-week periods. Hypothetical epidemic curves for the 2003 (Figure 1A) and 2009 (Figure 1B) outbreaks under different scenarios for response times (res) of vector control activities to a dengue introduction Surveillance has served as a basis for important public health responses to new threats, and as a source of invaluable information for health providers and policy makers. A budget proposal to stop the U.S. Centers for Disease Control and Prevention (CDC) funding in surveillance and research for mosquito-borne diseases such as dengue and West Nile virus has the potential to leave the country ill-prepared to handle new emerging diseases and manage existing ones. The present article uniquely integrates infectious disease models with economic analysis, taking advantage of a unique detailed dataset. By coupling a mathematical model with cost analysis we were able to evaluate the impact of delayed control responses to dengue fever, a mosquito-transmitted disease of global importance, in an economically developed urban environment. Our analysis clearly shows that the total costs of preparedness through surveillance are far lower than the ones that follow the introduction of vector-borne pathogens. Our findings will help provide a science-based justification for reassessment of the current proposal to slash the budget of the CDC vector-borne diseases program. More generally our study demonstrates the power of rigorous analysis of carefully collected data for a balanced assessment of the economic implications of a public health program shift. (res = 2, 4, 6 and 8 weeks) were computed by estimating the number of cases in the absence of control (between t0 and res) using R0, and then generating the rest of each epidemic time series by multiplying the number of cases by the estimated post intervention Rt in the original series. A response within 2 weeks of an introduction was assumed to occur only when active vector surveillance was in place (incurring a continuous cost), whereas delays in response of 68 weeks occurred when active disease and vector surveillance were eliminated. Direct and indirect costs per case provided by the Cairns Public Health Unit of Queensland Health, Australia (Table 1), were used to estimate the cumulative cost (i (...truncated)