In a population with stupid, superstitious people who cut the throats of the tracers. I'm not saying we are better, but we have a larger number of literate people who will behave mostly rationally.
I saw a doctor on TV who discussed an experiment, where a traceable but mild cold virus was smeared from an infected hand onto one single doorknob at a business.
Half of the office workers were infected in one day. It jumped from knob to hand to coffee pot handle to bathroom door knob etc etc.
Ebola only takes 1-10 virons to infect a person, and it can remain viable outside the body for days, for example, all over that ambulance, which continued to be used by several ambulance crews in contact with many patients after it was contaminated.