Fig. 1. : virological and climatic data in the city of Salvador, state of Bahia, Brazil, from May 2009-August 2011. Bars represent the influenza (Flu) virus detected. The X-axis shows the years and respective months and the left Y-axis shows the absolute number of positive specimens for influenza viruses (black bars). The right side Y-axis shows the average temperature (ºC), relative air humidity (%) and rainfall (mm x 10). In 2009, the total annual rain volume was 1,176 mm, in 2010, 1,780 mm, and 2011, 1,470 mm.