Abstract
BackgroundDengue has propagated widely through the Americas. Most countries have not been able to maintain permanent larval mosquito control programs, and the long-term effects of control actions have rarely been documented.MethodologyThe study design was based on a before-and-after citywide assessment of Aedes aegypti larval indices and the reported incidence of dengue in Clorinda, northeastern Argentina, over 2003–2007. Interventions were mainly based on focal treatment with larvicides of every mosquito developmental site every four months (14 cycles), combined with limited source reduction efforts and ultra-low-volume insecticide spraying during emergency operations. The program conducted 120,000 house searches for mosquito developmental sites and 37,000 larvicide applications.Principal FindingsRandom-effects regression models showed that Breteau indices declined significantly in nearly all focal cycles compared to pre-intervention indices clustered by neighborhood, after allowing for lagged effects of temperature and rainfall, baseline Breteau index, and surveillance coverage. Significant heterogeneity between neighborhoods was revealed. Larval indices seldom fell to 0 shortly after interventions at the same blocks. Large water-storage containers were the most abundant and likely to be infested. The reported incidence of dengue cases declined from 10.4 per 10,000 in 2000 (by DEN-1) to 0 from 2001 to 2006, and then rose to 4.5 cases per 10,000 in 2007 (by DEN-3). In neighboring Paraguay, the reported incidence of dengue in 2007 was 30.6 times higher than that in Clorinda.ConclusionsControl interventions exerted significant impacts on larval indices but failed to keep them below target levels during every summer, achieved sustained community acceptance, most likely prevented new dengue outbreaks over 2003–2006, and limited to a large degree the 2007 outbreak. For further improvement, a shift is needed towards a multifaceted program with intensified coverage and source reduction efforts, lids or insecticide-treated covers to water-storage containers, and a broad social participation aiming at long-term sustainability.
Highlights
The global incidence of dengue has increased exponentially since 1955 to reach 1–50 million infections per year in 2000–2005 [1]
A shift is needed towards a multifaceted program with intensified coverage and source reduction efforts, lids or insecticide-treated covers to water-storage containers, and a broad social participation aiming at long-term sustainability
A multifaceted intervention program is needed. It should include intensified surveillance and treatment coverage with larvicides that last longer, more efforts on reducing the potential number of mosquito development sites, and a broad social participation aiming at long-term sustainability
Summary
The global incidence of dengue has increased exponentially since 1955 to reach 1–50 million infections per year in 2000–2005 [1]. Dengue has become the most important arboviral disease of humans, and an increasing urban health and economic problem in tropical and subtropical regions worldwide. Current dengue control strategies seek to reduce Ae. aegypti abundance; optimize diagnosis and treatment of dengue cases, and decrease the frequency, magnitude and severity of dengue epidemics through integrated control strategies [6]. Prior to 2000, dengue virus activity was limited in Clorinda (i.e., 36 imported cases in 1999). In immediate response to this outbreak, febrile syndromic surveillance commenced at the public hospitals and health care centers, and emergency vector control operations (focal treatment with 1% temephos, indoor space spraying with pyrethroid insecticides, citywide vehicle-mounted ULV insecticide spraying, and elimination of discarded containers in the least affluent neighborhoods) were initiated. Vector suppressive actions only covered 5% of Clorinda during the second semester of 2001, when the overall prevalence of IgG antibodies to dengue virus was 11.9% (Elena Pedroni, unpublished data, December 2001). Emergency vector control operations over three weeks reduced house index only by ,45% shortly after interventions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
