A decade of arbovirus emergence in the temperate southern cone of South America: dengue, Aedes aegypti and climate dynamics in Córdoba, Argentina

Background: Argentina is located at the southern range of arboviral transmission by Aedes aegypti and has experienced a rapid increase in arbovirus transmission in recent years. This study aims to present the study design and findings from the first 9 years of an entomological surveillance work that began in Cordoba following the emergence of dengue one decade ago. We also investigate the temporal dynamics of Ae. aegypti , dengue cases, and local climate, and their lagged associations. Methods: From 2009 to 2017, larval surveys were conducted monthly, from November to May, in 600 randomly selected households distributed across the city. From 2009 to 2013, ovitraps (n=177) were sampled weekly to monitor the oviposition activity of Ae. aegypti. Cross correlation analysis was used to identify significant lag periods between climate, entomological and epidemiological variables. Results: Aedes aegypti abundance peaked once annually (from January to March), followed by a peak in autochthonous dengue transmission in April. We identified a notable increase in the proportion of homes with juvenile Ae. aegypti (from 5.7% of homes in 2009-10 to 15.4% of homes in 2016-17). The mean number of eggs per ovitrap was positively associated with mean temperature. Monthly juvenile Ae. aegypti abundance was not associated with either autochthonous or imported dengue cases. Autochthonous dengue transmission was negatively correlated with lagged temperature and precipitation. Conclusions: These findings suggest increasing the risk of arbovirus transmission in this temperate region. These results can guide targeted vector control interventions and the development of climate services for the public health sector to reduce the burden of arboviral diseases.