Climate change and the rising incidence of dengue in Argentina

BACKGROUNDOne of the most important consequences of climate change is the increased spread of dengue from tropical and subtropical regions to temperate areas around the world. Climate variables such as temperature and precipitation influence the dengue vectors biology, physiology, abundance, and life cycle. Thus, an analysis is needed of climate changes and their possible links with the growing occurrence of epidemics recorded in recent decades. OBJECTIVESTo assess the increasing incidence of dengue driven by climate change at the southern limits of dengue virus transmission in South America. METHODSWe analyze the evolution of climate, epidemiological, and biological variables, comparing a period without the presence of dengue cases to a more recent period with the occurrence of cases and, consequently, of important epidemics. Temperature and precipitation are the climate variables evaluated, the total number of cases and incidence of dengue are the epidemiological variables, and finally, the optimal temperature ranges for transmission of the dengue vector is the biological variable. RESULTSThe presence of dengue cases and epidemic outbreaks are observed to be consistent with positive temperature trends and anomalies. Dengue cases do not seem to be associated with precipitation trends and anomalies. The number of days with optimal temperatures for dengue transmission increased from the period without dengue cases to the period with the presence of dengue cases. However, the number of months with optimal transmission temperatures was the same in both periods. CONCLUSIONSThe higher incidence of dengue virus (DENV) and its expansion to different regions of Argentina seem to be associated with temperature increases in the country during the past decades. The active surveillance of both the vector and associated arboviruses will make it possible to assess and predict the occurrence of epidemics, based on the accelerated changes in climate. Such surveillance should go hand in hand with efforts to improve the understanding of the mechanisms driving the geographic expansion of dengue and other arboviruses beyond the current limits.