Decades ago, the government of Rio de Janeiro used to do a pretty good job of suppressing mosquitoes, but in recent years they have cut back funding for these efforts. As a result, mosquito-borne diseases such as dengue fever have become more prevalent. A first infection with dengue is typically painful, but not fatal. However, a second infection can lead to dengue hemorrhagic fever, which can be life-threatening. Recently, the Brazilian Health Ministry has warned that Rio de Janeiro faces a major dengue epidemic.
In 2001, my wife and I visited Rio during a dengue epidemic that infected several of our friends and acquaintances. We were invited to attend a film school in the Vidigal favela, but we chose not to accept the invitation because we had heard that dengue was spreading there.