 The udders of the cow are on the underside of the cow. So there is really no way to sterilely milk a cow and be sure that there is no bacteria entering the milk at that point. E. coli, campylobacter, salmonella infections can cause fever, diarrhea, and abdominal pain, but they can also cause more severe disease, including bloody diarrhea, kidney failure, and other complications. Listeria, as Dr. Miller noted, can cause meningitis.