Defining Challenges and Proposing Solutions for Control of the Virus Vector Aedes aegypti

The mosquito Aedes aegypti is the primary vector of three important viral diseases—dengue, yellow fever, and chikungunya—and is capable of transmitting a number of others. Ae. aegypti, which bites during daylight, is uniquely domestic among mosquito vectors: it mates, feeds, rests, and lays eggs in and around human habitation. Control of this mosquito should lead to control of disease, and there are well-documented historical examples of both yellow fever and dengue being eliminated or significantly reduced through Ae. aegypti control [1]. Construction of the Panama Canal was possible only after US Army Surgeon General William Gorgas stopped yellow fever transmission among workers by eliminating Ae. aegypti breeding sites. Fred Soper, of the Rockefeller Foundation, led the highly successful Ae. aegypti eradication program during the 1950s and 1960s that extinguished yellow fever and dengue transmission from most of Central and South America. More recently, Singapore and Cuba greatly reduced risk of dengue transmission by means of anti–Ae. aegypti legislation and actions. Use of the predatory crustacean Mesocyclops is preventing dengue transmission in parts of Vietnam [2]. Unfortunately, these successes are exceptions that were often too shortlived. Dengue has reoccupied Latin America and increases yearly; most of Southeast Asia remains highly endemic. Despite the availability of a vaccine, yellow fever outbreaks occur with dismaying frequency in Africa and Latin America. Chikungunya caused epidemics during 2005–2006 in the Indian Ocean region that were the largest yet recorded. In some regions, such as Sudan, all three viruses coexist. The reasons for failure are numerous. Spreading urbanization increases the habitat for expanding Ae. aegypti populations, rapid global migration increases the potential for vector and virus dissemination, poverty hobbles the efforts of individuals and communities to carry out effective protective measures, and even when resources for control exist, they are too often ineffectively applied [3]. An international panel (see Acknowledgments) met at Fort Collins, Colorado, United States, in May 2006 to critically examine why Ae. aegypti control has so seldom been successful in eliminating disease and to recommend measures to increase the opportunities for success. Consideration of control methods was limited to technologies now available or that could be soon developed; therefore, methods depending on genetical manipulation, such as genomic transformations and sterile male releases, were not discussed. There was unanimous agreement that elimination or significant reduction of Ae. aegypti populations is an effective and proven method for disease prevention. After reviewing examples of successful and failed programs, two issues especially worthy of attention were identified: (1) program design and management—specifically, sustainability, goal-setting, and surveillance/assessment—and (2) Defining Challenges and Proposing Solutions for Control of the Virus Vector Aedes aegypti