Infectious: communicable by infection, as from one person to another or from one part of the body to another.
I volunteer at a food pantry and was struck by how quickly the mood can shift from good to bad. I was a witness to this phenomenon recently. I was working at the front desk and had the unfortunate task of helping someone who was just plain mean. I swallowed my ego and helped her. I found her in the computer while she was hurling insults at me, but I just kept smiling. On the inside, I was ready to jump across the counter and choke her so she would not be able to enjoy the food that she was about to receive. I felt this infectious behavior begin to spread throughout the food pantry. It started with people bashing her behind her back and then it spread into the break room and changed the conversation to how miserable people were in general. People began complaining about the day and how awful it was. I felt like I needed to reverse the mood. I changed the subject to one of how many people we do help in a day that are appreciative of what we do, and almost instantly it got a bit brighter in the room. I also hinted that maybe this woman was so very unhappy with the situation she was in, and maybe she was embarrassed and didn’t how to handle it. The infection had changed from bad to good. Just like an antibiotic can do wonders, so can a bit of positive reinforcement.