a mosquito doesnt create a stagnant pond. it seeks one out in order to proliferate. what we eat creates the internal environment. bugs will grow there that thrive in that environment.
it takes very specific controlled environments in order to grow pathogens in a laboratory. each species requires specific and sometimes different medium to grow on. if anything is off - moisture content, temperature, pH, etc, you aint gonna get them to grow. like anna(jody foster) told the kings children in school, "if you wish to do the impossible, change the climate(environment)." people have created a cesspool in their bodies. no wonder the cleanup crew keeps showing up early.