**3. The situation of dengue and Chikungunya fever in Mexico**

A recent study estimated that up to 390 million dengue virus (DENV) infections, including close to 100 million cases of dengue disease manifestations, occur annually across the world [24]. *Ae. aegypti* and DENV were widely distributed in the Americas in the early 1900s, but a campaign against yellow fever initiated in 1947 and continued to the early 1970s resulted in both the mosquito and its associated viruses being eliminated from most of Central and South America and from Mexico [25]. Success then bred failure as resources were diverted to other health problems. From the 1980s, *Ae. aegypti* has reemerged in the Americas, facilitated by uncontrolled urbanization providing ample opportunities for mosquito breeding and popu‐ lation growth [1,25]. The mosquito now has regained the full extent of its range from a century ago. This reemergence of the vector combined with global trafficking of DENV in infected humans through increased air travel have led to the Americas becoming hyperendemic, with cocirculation of all four DENV serotypes in many areas [26,27]. In Mexico, dengue reemerged with a DENV-1 outbreak in 1979 followed by outbreaks of the other serotypes in the next two decades [25,28,29]. In 2009, a major dengue epidemic with nearly 250,000 reported clinical cases occurred in Mexico (55,363 confirmed) and this epidemic has continued through 2010 with ~58,000 clinical cases (22,352 confirmed) , 2011 with ~68,000 cases (15,578 confirmed) , 2012 with ~165,000 cases (84,612 confirmed) , 2013 with ~232,000 cases (62,330 confirmed) , 2014 with 125,000 cases (32,100 confirmed), and 2015 (up to September 25, 2015 ~125,000 clinical cases with 13,454 confirmed) [30].

The autochthonous transmission of Chikungunya in the Region of the Americas was first detected on December 2013. By July 2014, an imported case was reported in Mexico, two more imported cases appeared on September 5. By the end of 2014, a total of 131 autochthonous confirmed cases were reported as well as a total of 13 imported cases; and ~7,500 confirmed cases by October 2, 2015 [30].
