Cost-effectiveness of Novel System of Mosquito Surveillance and Control, Brazil

Kim M. Pepin, Cecilia Marques-Toledo, Luciano Scherer, Maira M. Morais, Brett Ellis, and Alvaro E. Eiras

Author affiliations: National Institutes of Health, Bethesda, Maryland, USA (K.M. Pepin); Colorado State University, Fort Collins, Colorado, USA (K.M. Pepin); Ecovec SA, Belo Horizonte, Brazil (C. Marques-Toledo, L. Scherer); Universidade Federal de Minas Gerais, Belo Horizonte (M.M. Morais, A.E. Eiras); Duke–National University of Singapore Graduate Medical School, Singapore (B. Ellis)

Abstract

Of all countries in the Western Hemisphere, Brazil has the highest economic losses caused by dengue fever. We evaluated the cost-effectiveness of a novel system of vector surveillance and control, Monitoramento Inteligente da Dengue (Intelligent Dengue Monitoring System [MID]), which was implemented in 21 cities in Minas Gerais, Brazil. Traps for adult female mosquitoes were spaced at 300-m intervals throughout each city. In cities that used MID, vector control was conducted specifically at high-risk sites (indicated through daily updates by MID). In control cities, vector control proceeded according to guidelines of the Brazilian government. We estimated that MID prevented 27,191 cases of dengue fever and saved an average of $227 (median $58) per case prevented, which saved approximately $364,517 in direct costs (health care and vector control) and $7,138,940 in lost wages (societal effect) annually. MID was more effective in cities with stronger economies and more cost-effective in cities with higher levels of mosquito infestation.

Dengue viruses cause ≈50 million infections annually worldwide, and ≈1% of these infections require hospitalization because of dengue hemorrhagic fever (1). Brazil accounts for ≈75% of all dengue cases in the Western Hemisphere (2), and during 2000–2005, Brazil reported more cases than any other country in the world (3). Since the reemergence of dengue in Brazil in 1982, there has been an epidemiologic shift to hyperendemicity (4,5) and more severe disease (5,6). Moreover, of all countries in the Western Hemisphere, Brazil has the highest economic losses caused by dengue ($1.35 billion) annually for direct medical and nonmedical costs and indirect costs from loss of work (7). This high economic cost of the disease occurs even after Brazil spent $1 billion annually on the dengue vector control program. Cost-effective methods of vector control are needed to decrease the huge economic effects of this disease in Brazil.
The most accurate method of assessing dengue risk by vector surveillance is one that specifically counts dengue vectors that are actively in search of a blood meal: adult female Aedes aegypti and occasionally Ae. albopictus mosquitoes. Ttraditional methods of vector monitoring in Brazil, which include surveys of larvae and pupae (8,9) and capture of adult mosquitoes by aspiration (10), are less specific and labor-intensive. Surveys of larvae target both vector sexes and can only predict the number of mosquitoes that will survive to adulthood, rather than directly measure adults. Capturing adults by aspiration does not specifically target female mosquitoes, is labor-intensive, and requires access to premises.
Fixed-position traps designed to capture gravid mosquitoes (e.g., MosquiTRAPs) (Ecovec SA, Belo Horizonte, Brazil) have been developed to reduce personnel costs and directly measure adult female mosquito abundance in Brazil (11,12). MosquiTRAPs have been implemented in the form of a large-scale mosquito surveillance system, Monitoramento Inteligente da Dengue (Intelligent Dengue Monitoring System [MID]; Ecovec SA), which is used to count mosquitoes in real time. MID involves weekly monitoring of MosquiTRAP (placed in a 300 m × 300 m grid format) counts and trapped-mosquito infection status with automated database updating (in situ mosquito data entry by cell phones directly to a Web-based database). The mosquito data are managed by a spin-off company (Ecovec SA), which provides daily updates to control personnel so they can specifically target highly infested areas. Preliminary results from 3 cities (Tres Lagoas in Mato Grosso do Sul State, and Presidente Epitacio and Bastos in Sao Paulo State) during 1 season of MID implementation showed that this system is effective in decreasing dengue cases (13). However, an estimate of cost-effectiveness for more cities over a longer period is needed for deciding whether MID should be maintained.
We evaluated the cost-effectiveness of supplementing vector control methods with MID in 21 cities in Minas Gerais State, Brazil, after use during 2 dengue seasons. We also identified factors that affected efficacy and cost-effectiveness of MID. We reported direct savings for health care costs and vector control activities separately from indirect savings for lost wages so that results are relevant to public health budgets and societal concerns.

Cost-effectiveness of Novel System of Mosquito Surveillance and Control, Brazil - Vol. 19 No. 4 - April 2013 - Emerging Infectious Disease journal - CDC