After last year’s record-busting drought in Brazil’s southeast, recent rainfall brought relief to residents—but also gave a helping hand to dengue-transmitting mosquitoes.
Last year’s dry spell deprived the mosquitoes of their favored breeding ground—stagnant puddles—and kept the fever at bay. By early March of this year, in contrast, Brazil had already reported at least 224,000 cases of dengue—162% more than in the same period in 2014.
The situation is especially bad for São Paulo, and many of this year’s worst-hit towns in that area had been spared during previous dengue outbreaks. Thus, fewer inhabitants have had a chance to develop natural immunity.