Zika emergence, persistence, and transmission rate in Colombia: a nationwide application of a space-time Markov switching model.

Zika, a viral disease transmitted to humans by Aedes mosquitoes, emerged in the Americas in 2015, causing large-scale epidemics. Colombia alone reported over 72,000 Zika cases between 2015 and 2016. Using national surveillance data from 1121 municipalities over 70 weeks, we identified sociodemographic and environmental factors associated with Zika's emergence, re-emergence, persistence, and transmission intensity in Colombia. We fitted a zero-state Markov-switching model under the Bayesian framework, assuming Zika switched between periods of presence and absence according to spatially and temporally varying probabilities of emergence/re-emergence (from absence to presence) and persistence (from presence to presence). These probabilities were assumed to follow a series of mixed multiple logistic regressions. When Zika was present, assuming that the cases follow a negative binomial distribution, we estimated the transmission intensity rate. Our results indicate that Zika emerged/re-emerged sooner and that transmission was intensified in municipalities that were more densely populated, at lower altitudes and/or with less vegetation cover. Warmer temperatures and less weekly-accumulated rain were also associated with Zika emergence. Zika cases persisted for longer in more densely populated areas with more cases reported in the previous week. Overall, population density, elevation, and temperature were identified as the main contributors to the first Zika epidemic in Colombia. We also estimated the probability of Zika presence by municipality and week, and the results suggest that the disease circulated undetected by the surveillance system on many occasions. Our results offer insights into priority areas for public health interventions against emerging and re-emerging Aedes-borne diseases.

Evaluación de índices entomológicos mediante herramientas electrónicas en Villavicencio, Meta, Colombia / Evaluation of entomological indices with electronic tools in Villavicencio, Meta, Colombia

Objetivo: Determinar la eficacia de dos herramientas electrónicas en el levantamiento de índices aédicos en la ciudad Villavicencio. Métodos: Se realizó un estudio de tipo observacional, analítico en dos barrios de la ciudad Villavicencio: Quintas de San Fernando y Cedritos. El formato de levantamiento de índices aédicos de la secretaría de salud fue diseñado en dos medios electrónicos. La eficacia fue determinada mediante datos efectivos recogidos y tiempo de entrega. Se calcularon índices aédicos, Breteau, vivienda y pupas. Se realizó encuesta para determinar actitudes frente a arbovirosis. Se realizó estadística descriptiva, pruebas de chi cuadrado y t-Student (p< 0,05). Resultados: Se evaluaron 67 predios en dos barrios. El índice de datos efectivos fue mejor en donde el acceso a internet era permanente (100 por ciento vs. 23,9 por ciento); el tiempo de entrega también se afectó por esta conexión. Se encontraron diferencias significativas en el número de viviendas positivas para Aedes aegypti entre los dos barrios (p= 0,0052); y para el número de tanques bajos positivos (p= 0,0123). De los encuestados, el 16,4 por ciento (IC95 por ciento 8,9 por ciento-27,5 por ciento) sabía que la transmisión fue por picadura de Ae. aegypti. Para el 79,1 por ciento, cada familia fue responsable de eliminar criaderos. Conclusiones: El uso de herramientas electrónicas permite acelerar el flujo de la información y crear un sistema eficaz, de fácil acceso y seguridad que podría implementarse permanentemente en la vigilancia entomológica y de salud pública(AU)

Objective: Determine the effectiveness of two electronic tools for the evaluation of aedic indices in the city of Villavicencio. Methods: An observational analytic study was conducted in two districts in the city of Villavicencio: Quintas de San Fernando and Cedritos. The form designed by the Ministry of Health to evaluate aedic indices was digitalized into two electronic media. Efficacy was determined on the basis of effective data collected and delivery time. An estimation was made of aedic indices, Breteau, household and pupae. A survey was conducted to determine attitudes to arbovirus infections. Use was made of descriptive statistics, chi-squared tests and Student's t-test (p< 0.05). Results: Sixty-seven households were evaluated in two districts. The effective data index was better in areas where access to the Internet was permanent (100 percent vs. 23.9 percent). Delivery time was also affected by Internet connection. Significant differences were found between the two districts in the number of positive households for Aedes aegypti (p= 0.0052), as well as in the number of positive ground water tanks (p= 0.0123). Of the respondents, 16.4 percent (95 percent CI, 8.9 percent-27.5 percent) were aware that transmission had been by the bite of Ae. aegypti mosquitoes. For 79.1 percent each family was responsible for eliminating the breeding sites. Conclusions: Use of electronic tools speeds up the flow of information and creates an effective, easily-accessible and safe system which could be permanently implemented for entomological and public health surveillance(AU)