INFECTIOUS DISEASES IN THE CONTEXT OF CLIMATIC CHANGES: THE EFFECTS OF CLIMATIC FACTORS ON DENGUE FEVER IN THE AMAZONIAN URBAN CENTER OF RIO BRANCO, BRAZIL

INTRODUCTION: Dengue is a mosquito-borne infection transmitted predominantly in urban and semi-urban areas and has become a major international public health concern since its incidence has grown dramatically in recent decades. Over 2.5 billion people are now at risk from dengue and WHO estimates there may be 50–100 million infections worldwide every year. Climate affects the dengue viruses and vector populations since temperature influences vector development rates, mortality, and behavior and also controls viral replication within the mosquito. Rainfall influences habitat availability for Aedes aegypti. The State of Acre records annually high incidences of dengue fever, mainly in its major urban center, Rio Branco. Located in the valley of the Acre River in northern Brazil, it is the most populous county in the state, with 305,954 inhabitants, almost half the state population. Based on the Pulse Brasil Project (www.pulse-brasil.org), a platform for understanding long-term sustainability of ecosystems and health, the aim of this study is to assess the interactions between climate variables and human health in Amazonia, and to explore the consequences of different policy options.

METHODS: Monthly dengue fever notifications for the city of Rio Branco for the period 2000-2012 were provided by the State Health Department. Climatic data based on the Meteorological Station Rio Branco was provided by the National Institute of Metereology (INMET). We applied a negative binomial poisson regression model to interpret the relationship between dengue cases and the climatic variables.

RESULTS: After the adjustment we observed that a rise in minimal temperature causes an increase of 37% in the risk of dengue fever in the city of Rio Branco. The model also projected a protective effect of variable insolation on dengue cases in such a way that a rise in insolation values produced a reduction in the risk of dengue fever of 20%. Peaks of maximum temperature also produced a negative effect on the dengue cases in Rio Branco, with a reduction of 12% in the number of cases, though not significant. Highest peaks of dengue fever were observed between 2009 and 2011.

CONCLUSIONS: All produced data will be available at the Pulse Brasil platform for free access by stakeholders who will look at climate predictions and determined which combination of temperature and rainfall changes corresponded to best- and worst-case scenarios in terms of dengue fever transmission.