Our language is so curious. “I have a bug,” we says, and the mental images can be varied: we hold a small cage with a little bug in it; we cradle a bug in her hands; a bug sits in our throat. The latter is probably the closest to what we mean: an invisible organism (bacteria or virus) has taken hold of us, attacked our integrity, and caused us to have certain symptoms such as a cough or a stomachache. The image is compelling, but is this really how we get sick?
Our notions of sickness are peculiar to our time and culture. Immersed as we are in this culture, these notions have the aura of absolute truth. We KNOW that bacteria exist: smart people see them under the microscope, and are able to influence them in one way or another. We KNOW that certain bacteria or viruses are associated with the appearance of certain symptoms: smart people tell us so. They also tell us that the fact that the “bugs” appear together with the symptoms means that the bugs caused the symptoms.