Background Arbovirus diseases such as dengue, Zika, and chikungunya are a public health threat in tropical and subtropical areas. In the absence of a vaccine or specific treatment, vector management (in this case the control of the primary vector Aedes aegypti) is the best practice to prevent the three diseases. A good understanding of vector behaviour, ecology, human mobility and water use can help design effective vector control programmes. This study collected baseline information on these factors for identifying the arbovirus transmission risk and assessed the requirements for a large intervention trial in Colombia. Methods Baseline surveys were conducted in 5,997 households, randomly selected from 24 clusters (neighbourhoods with on average 2000 houses and 250 households inspected) in the metropolitan area of Cucuta, Colombia. The study established population characteristics including water management and mobility as well as larval-pupal indices which were estimated and compared in all clusters. Additionally, the study estimated disease incidence from two sources: self-reported dengue cases in the household survey and cases notified by the national surveillance system. Results In all 24 study clusters similar social and demographic characteristics were found but the entomological indicators and estimated disease incidence rates varied. The entomological indicators showed a high vector infestation: House Index = 25.1%, Container Index = 12.3% and Breteau Index = 29.6. Pupae per person Index (PPI) as an indicator of the transmission risk showed a large range from 0.22 to 2.04 indicating the high transmission risk in most clusters. The concrete ground tanks for laundry –mostly outdoors and uncovered- were the containers with the highest production of Aedes mosquitoes as 86.3% of all 17,613 pupae were identified in these containers. Also the annual incidence of dengue was high: 841.6 self-reported cases per 100,000 inhabitants and the dengue incidence notified by the National surveillance system was 1,013.4 cases per 100,000 in 2019. Only 2.2% of the households used the container water for drinking. 40.3% of the study population travelled during day (when Aedes mosquitoes bite) outside their clusters. Conclusions: The production of Aedes aegypti mosquitoes occurred almost exclusively in concrete ground tanks for laundry (lavadero) which are the primary intervention target. The baseline study provides important evidence for the design and implementation of a cluster randomized intervention trial in Colombia.

Background Arbovirus diseases such as dengue, Zika, and chikungunya are a public health threat in tropical and subtropical areas. In the absence of a vaccine or specific treatment, vector management (in this case the control of the primary vector Aedes aegypti) is the best practice to prevent the three diseases. A good understanding of vector behaviour, ecology, human mobility and water use can help design effective vector control programmes. This study collected baseline information on these factors for identifying the arbovirus transmission risk and assessed the requirements for a large intervention trial in Colombia. Methods Baseline surveys were conducted in 5,997 households, randomly selected from 24 clusters (neighbourhoods with on average 2000 houses and 250 households inspected) in the metropolitan area of Cucuta, Colombia. The study established population characteristics including water management and mobility as well as larval-pupal indices which were estimated and compared in all clusters. Additionally, the study estimated disease incidence from two sources: self-reported dengue cases in the household survey and cases notified by the national surveillance system. Results In all 24 study clusters similar social and demographic characteristics were found but the entomological indicators and estimated disease incidence rates varied. The entomological indicators showed a high vector infestation: House Index = 25.1%, Container Index = 12.3% and Breteau Index = 29.6. Pupae per person Index (PPI) as an indicator of the transmission risk showed a large range from 0.22 to 2.04 indicating a high transmission risk in most clusters. The concrete ground tanks for laundry –mostly outdoors and uncovered- were the containers with the highest production of Ae. aegypti as 86.3% of all 17,613 pupae were identified in these containers. Also, the annual incidence of dengue was high: 841.6 self-reported cases per 100,000 inhabitants and the dengue incidence notified by the National surveillance system was 1,013.4 cases per 100,000 in 2019. Only 2.2% of the households used container water for drinking. 40.3% of the study population travelled during the day (when Aedes mosquitoes bite) outside their clusters. Conclusions The production of Ae. aegypti mosquitoes occurred almost exclusively in concrete ground tanks for laundry (lavadero), the primary intervention target. The baseline study provides necessary evidence for the design and implementation of a cluster randomized intervention trial in Colombia.

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Background: Vector surveillance has been ongoing since the 1960’s through larval surveys, which are not useful to serve as an alarm indicator for outbreak prediction since they are usually done in an unsystematic way. This can be achieved with the ovitrap system. This study aimed to determine the feasibility, required resources and costs of installing and maintaining an ovitrap vector surveillance system in a municipality of Colombia.Methods: The study applied a cross sectional design including the mapping of target houses, implementation of the ovitrap system (following the Mexican ovitrap model) and an analysis of resource requirements. The mapping was done using street maps from Google Earth. 40 ovitraps were manufactured and installed on 10 blocks (1 ovitrap on each side of every cardinal point of the block, every third block), and revised weekly by two vector control technicians for a four-week period. Personal interviews with the technicians regarding costs of daily income, transport needs of human resources and requirement of equipment for manufacturing and maintaining the ovitraps, were conducted for the cost analysis. Results: A map of the 40 ovitrap geolocations facilitated the implementation. Entomological findings were expressed with six indicators. These were (results in brackets): Process indicators: Percent of acceptance by houseowners (76.9%), Percent of relocation of traps (5%), Percent of ovitraps examined in 4 study weeks (97.5%, 97.5%, 97.5%, 100%), Percent of intact ovitraps (92.5%, 97.5%, 97.5%, 100%). Result indicators: Percent of positive ovitraps (80%, 90%, 75%, 97.5%), Percent of positive blocks (100%). Operational indicators: Time for the installation of 40 ovitraps (10h15m), time for the weekly reading and reinstallation (7h40m, 7h15m, 7h53m, 7h), Time for data transmission to the operational centre (8h, 4h, 2h, 2h). Cost of installing and reviewing 40 ovitraps during four weeks: COL$1,142,304.47 or US$297. Projection of costs for covering the entire municipality of Los Patios (95000 inhabitants) with 348 ovitraps in one year: COL$24,631,329.27 or US$6,404.14. Conclusions: The implementation of the ovitrap system is feasible and affordable in Colombian municipalities and other endemic areas since most of the costs are already covered by the vector control services (salaries and transport).