How about spreading those Bed Bugs that are infiltrating every nook and cranny of New York?
Or fecal matter...Blech!
"How Bedbugs Spread"
"Bedbugs often spread by hitching rides on people's clothing. They jump from host to host when people brush up against each other in crowds (yet another reason to keep your distance on the subway)..."
When I was in high school, the wrestling teams in our area all had their season cancelled because kids were coming down with strange skin diseases from the wresting mats.