Pheromones

A lot of people have commented on the infected people being able to find sex partners (although DJ may have ruffied Sam). And there is the question as way people in general were not more alarmed with the appearance of the infected. How could Sam's manager allow her to work let allow require her to make and server food. People have even mentioned she probably smelled bad.

But what if the infection gives off pheromones that make the infected seem more attractive? This is a disease that is spread through close contacts to the infected. So if it could hide the symptoms from potential victims that would work in its favor.