In the lead-up to the 2016 Rio, Brazil Olympics, an outbreak of the Zika virus and Dengue fever threatened to throw the games into disarray. The worry was that fearing for their lives, participants would boycott the XXXI Olympiad. Thankfully, that did not happen because Brazilian authorities went all out to rid the country of mosquitoes, the vectors in the disease.
Both the Zika virus and Dengue fever are spread by mosquitoes and are deadly than the killer malaria.