Estudo da correlação entre variáveis meteorológicas e a incidência de casos de dengue em Maceió, Alagoas, Brasil

Abstract

The present work had the objective of identifying the correlation between the temporal series of incidence of dengue cases and meteorological variables in the city of Maceió, Alagoas, through the investigation of periodicity variations in the whole time series of cases of dengue incidence and Of the temporal series of the time variables and of the detection of the corresponding time delay periods of the meteorological variables that correlate with the incidence of dengue cases. For the analysis and understanding of these aspects, real monthly data were used for the meteorological variables precipitation, cloudiness, relative air humidity, maximum temperature, average temperature, minimum air temperature, insolation, maximum speed and average wind, selected between January From December 1998 to December 2015 at Maceió Climatological Automatic Station, from INMET's BDMEP. For the same study period, data were also obtained on the number of notified cases of dengue in the municipality, available free of charge through the TABNET / DATASUS database. To identify the dominant periodicity in the signals of the time series of the study, continuous wavelet analysis was used. In order to investigate the relation between the time series, the criterion of crossed wavelet, wavelet coherence and phase angle was used. It was found that all variables presented individual dominant peaks with a scale of approximately 10 to 14 months. However, the cloudiness and insolation variables also showed concentrated energy in a scale less than 6 months. All cross-power spectra also showed dominant periodicity with approximately annual scale, that is, both the series of dengue incidence and the series of meteorological variables had the same high energy. It is worth noting that the variables precipitation, cloudiness and average air temperature also presented periodicity on a scale of 5 to 7 months. When the approximately 12-month scale was analyzed in correlated power spectra, the cloudiness variable, maximum wind speed, mean wind velocity and sunshine did not show a positive influence on the change in dengue incidence, that is, they did not increase the number of disease. Overall, when analyzed at approximately annual scale, the increase in the incidence of dengue cases in Maceió presented a temporal delay of 3 weeks when correlated to precipitation, temporal delay of 6 to 11 weeks relative to relative humidity, 15 weeks when Correlated to the maximum air temperature, 12 to 15 weeks in relation to the average air temperature, and a time delay of 9 to 14 weeks when correlated to the minimum air temperature. Thus, the increase in the occurrence of dengue cases is strictly associated with the duration of the dominant periodicity of precipitation and the maximum temperature of the air, being placed as indicators of dengue cases in this scale. However, it is important to note that for scales less than 6 months, the meteorological variables cloudiness and sunshine are indicated as indicators that presented good results, with the incidence of dengue cases presenting a temporal delay of approximately 5 weeks in relation to these two meteorological variables.