**4. Vector control in Mexico**

in containers found in the peridomestic environment, and that is where the immature larvae and pupae develop [10,11]. *Ae. aegypti* is ubiquitous in populated areas of Mexico up to ~1,500 m above sea level [12]. *Aedes albopictus*, which is the primary vector of dengue and Chikungunya viruses, is ubiquitous in rural settings [13–15]. This human biter was introduced into Texas in the 1980s and has spread widely in northern and central Mexi‐

Urban environments have favored the presence and abundance of *Ae. aegypti* in 30 of 32 states of Mexico (with exception of Tlaxcala and the Federal District) [19–21], and conse‐ quently, they have caused the endemic transmission of dengue and more recently, in 2014,

Mexico is in the southern part of North America, between 14° 32 and 32° 43 North and 86° 42 and 118° 27 West. The country is divided administratively into 31 states and one federal district (Mexico City). Mexico has a land area of 1,964,375 km². It is surrounded by the Gulf of Mexico and Caribbean Sea to the east, the United States of America to the north, the Pacific Ocean to the south and west, and Belize and Guatemala to the southeast. The main features of the physiography of Mexico are Northern and Southern Plateau. Two mountain chains, the Sierra Madre Oriental on the east and The Sierra Madre Occidental on the west, leave plains along the shores of the Gulf of Mexico and the Pacific Ocean. The Sierra Madre Oriental obstructs the circulation of air from the Gulf of Mexico toward Northern and Central Mexico. This characteristic on physiography allows a variety of climates, and the altitude performs a dominant effect on temperature. The prevalent climate conditions are dry to arid in the country. The North territory (47.7%) presents arid and semiarid conditions (23.5%), subhumid with 7 months of long dry season prevailing in Central Mexico, 16.3% presents dry tropical mainly the shores, 12.4% of the territory located in Southern Mexico presents humid tropical climate, and in both mountain chains small areas with humid temperate climate are found [23].

**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

co, and the far southern part of the country [16–18].

of Chikungunya [22].

**2. Study area**

100 Insecticides Resistance

Since 1950, operational vector control programs in Mexico have used a series of insecticides to control *Ae. aegypti* [31]. The organochlorine insecticide DDT was used extensively for indoor house spraying from 1950 to 1960 and was used in some locations as recently as 1998. In recent decades, the chemical control of mosquito larvae has relied on the use of organophosphate insecticides with temephos as the active ingredient. The adulticide malathion was used for ultra-low volume (ULV) space spraying from 1981 to 1989. An oil-based formulation of chlorpyrifos was registered for use in some locations in Mexico to control the adult stage of the mosquito from 1996 to 1999. The organophosphates as adulticides were replaced by pyrethroids according to the Norma Official Mexicana NOM-032-SSA2-2002 [32]. The pyreth‐ roid permethrin was applied as a sole adulticide in Mexico for more than a decade.

On June 1, 2011, a new policy was published in NOM-032-SSA2-2010 [33] that established the characteristics of the insecticides to be used for vector control in Mexico. The selection of the insecticides should be based on vector resistance, effectiveness, and safety related to exposure. The list of insecticides has since been updated each year [34]. A new policy published on April 16, 2015 (NOM-032-SSA2-2014) [35], maintained the same requirements practically as the regulation published in 2011.
