VECTOS: An Integrated System for Monitoring Risk Factors Associated With Urban Arbovirus Transmission.

In Colombia, as in many Latin American countries, decision making and development of effective strategies for vector control of urban diseases such as dengue, Zika, and chikungunya is challenging for local health authorities. The heterogeneity of transmission in urban areas requires an efficient risk-based allocation of resources to control measures. With the objective of strengthening the capacity of local surveillance systems to identify variables that favor urban arboviral transmission, a multidisciplinary research team collaborated with the local Secretary of Health officials of 3 municipalities in Colombia (Giron, Yopal, and Buga), in the design of an integrated information system called VECTOS from 2015 to 2018. Information and communication technologies were used to develop 2 mobile applications to capture entomological and social information, as well as a web-based system for the collection, geo-referencing, and integrated information analysis using free geospatial software. This system facilitates the capture and analysis of epidemiological information from the Colombian national surveillance system (SIVIGILA), periodic entomological surveys-mosquito larvae and pupae in premises and peridomestic breeding sites-and surveys of knowledge, attitudes, and practices (KAP) in a spatial and temporal context at the neighborhood level. The data collected in VECTOS are mapped and visualized in graphical reports. The system enables real-time monitoring of weekly epidemiological indicators, entomological indices, and social surveys. Additionally, the system enables risk stratification of neighborhoods, using selected epidemiological, entomological, demographic, and environmental variables. This article describes the VECTOS system and the lessons learned during its development and use. The joint analysis of epidemiological and entomological data within a geographic information system in VECTOS gives better insight to the routinely collected data and identifies the heterogeneity of risk factors between neighborhoods. We expect the system to continue to strengthen vector control programs in evidence-based decision making and in the design and enhanced follow-up of vector control strategies.

Comparison of the efficacy of long-lasting insecticidal nets PermaNet® 2.0 and Olyset® against Anopheles albimanus under laboratory conditions.

Insecticide-treated nets provide a reduction in human-vector contact through physical barrier, mortality and/or repellent effects that protect both users and non-users, thereby protecting the wider community from vector-borne diseases like malaria. Long-lasting insecticide-treated nets (LLINs) are the best alternative. This study evaluated the bioefficacy of LLINs PermaNet® 2.0 and Olyset® under laboratory conditions with Anopheles albimanus. The laboratory strain was evaluated for insecticide susceptibility with selected insecticides used for malarial control. Regeneration time and wash resistance were evaluated with the standard bioassay cone technique following WHO guidelines. Heat assistance was used for Olyset® nets; the nets were exposed to four different temperatures to speed the regeneration process. The regeneration study of PermaNet® 2.0 showed that efficacy was fully recovered by 24 h after one and three washes and wash resistance persisted for 15 washes. Regeneration of Olyset® nets was not observed for nets washed three times, even with the different temperature exposures for up to seven days. Thus, for Olyset® the wash resistance evaluation could not proceed. Differences in response between the two LLINs may be associated with differences in manufacturing procedures and species response to the evaluated LLINs. PermaNet® 2.0 showed higher and continuous efficacy against An. albimanus.

Comparison of the efficacy of long-lasting insecticidal nets PermaNet® 2.0 and Olyset® against Anopheles albimanus under laboratory conditions

Insecticide-treated nets provide a reduction in human-vector contact through physical barrier, mortality and/or repellent effects that protect both users and non-users, thereby protecting the wider community from vector-borne diseases like malaria. Long-lasting insecticide-treated nets (LLINs) are the best alternative. This study evaluated the bioefficacy of LLINs PermaNet® 2.0 and Olyset® under laboratory conditions with Anopheles albimanus. The laboratory strain was evaluated for insecticide susceptibility with selected insecticides used for malarial control. Regeneration time and wash resistance were evaluated with the standard bioassay cone technique following WHO guidelines. Heat assistance was used for Olyset® nets; the nets were exposed to four different temperatures to speed the regeneration process. The regeneration study of PermaNet® 2.0 showed that efficacy was fully recovered by 24 h after one and three washes and wash resistance persisted for 15 washes. Regeneration of Olyset® nets was not observed for nets washed three times, even with the different temperature exposures for up to seven days. Thus, for Olyset® the wash resistance evaluation could not proceed. Differences in response between the two LLINs may be associated with differences in manufacturing procedures and species response to the evaluated LLINs. PermaNet® 2.0 showed higher and continuous efficacy against An. albimanus.

Insecticide resistance status of Aedes aegypti in 10 localities in Colombia.

Insecticide resistance is one of the major threats to the effectiveness of vector control programs. In order to establish a baseline susceptibility profile of Aedes aegypti in the southwest of Colombia, 10 localities in four Departments (States) were evaluated. Standardized WHO bioassay, CDC bottle bioassay and microplate biochemical assays of non-specific ß-esterase (NSE), mixed function oxidases (MFO) and acetylcholinesterase were used. Cross resistance was evaluated with field collected mosquitoes that underwent selection pressure in the laboratory from DDT, propoxur and lambdacyhalothrin during three alternate generations. Mosquitoes with mortality rates below 80% in bioassays were considered resistant. Insecticide resistance varied geographically. Insecticide resistance was observed in 100% of localities in which mosquitoes were exposed to DDT, bendiocarb and temephos using both assays. WHO bioassays showed susceptibility to pyrethroids in all the localities evaluated, however CDC bottle bioassays showed decreases in susceptibility especially with lambdacyhalothrin. All localities showed susceptibility to the organophosphate malathion. Mosquitoes from eight regions with evidence of resistance to any of the insecticide evaluated were also evaluated biochemically. Mosquitoes from five of these regions had increased levels of NSE and two regions had increased levels of MFO. Increase levels of NSE explain partially the low susceptibility to temephos found in all the localities. However, the biochemical mechanisms evaluated do not explain all the resistance observed. Cross resistance was observed between the DDT-selected strain and lambdacyhalothrin, and between the lambdacyhalothrin-selected strain and propoxur and vice versa. The selected strains do not show changes in the biochemical assays evaluated, therefore the observed cross-resistance suggests different biochemical mechanisms. This study shows that Ae. aegypti from Colombia can develop resistance to most of the insecticide classes in the market. Periodic surveillance of insecticide resistance is necessary in order to maintain effective interventions. This study helped to establish the National Network for the surveillance of the insecticide resistance in Colombia.