The sign in the fifth-floor restroom read, “Dirty hands spread disease. Always use soap.”  Dave rinsed his hands with water, quickly ran his fingers through his hair, and then rushed into the hallway, already late for biology class.
There was an overwhelming smell as he entered the classroom, and he could immediately tell why: on each counter was sitting the day’s project, a fetal pig.  “Do these things have to stink?” he asked his teacher.  “Well, Dave, if they didn’t ‘stink’ of the formaldehyde, they would be rotting and could be spreading diseases.  Now let’s get started.” the teacher said.  At the end of class period, they were told, “Be sure to wash your hands thoroughly before leaving this classroom.”
This reminded Dave of the lectures they had earlier in the semester about diseases caused by pathogens and how these diseases are spread.  As he looked around the classroom, Dave was aware of the other students.  Most were gathering up their books to go directly to lunch without washing their hands, Gail and Susan were sharing a bottle of water, Beth was rubbing her eyes, and Jim was coughing without covering his mouth!  Suddenly, Dave had a mental image of pathogens everywhere: lying on hands and counter tops, floating in the air-and all of these pathogens were looking for someone to infect!  Dave shook his head to get rid of this mental image.  Then he went to the sink and carefully washed his hands again; this time with soap.
Identify and discuss the examples of the potential disease transmission methods that are included in Dave’s story, and describe what should have been done to eliminate these risks.