tomato, tomato

It is inevitable that in a batch of tomatoes, if one were to go sour and ultimately grow puss and fungus on it, the rest of the tomatoes will go bad as well because the contaminated tomato will have spread it's illness to the adjacent tomatoes.

Is it true then that this may be the case with individuals as well? Could just one mere individual, who is foul and ill-infused have such a profound effect on the the individuals around him that he may consequently alter their initial perceptions, thoughts and sentiments? Could just one person, with a malaise, spread this to those around him? Needless to say, groups are far more pervasive and influential than someone who stands alone, so when this does happen, the repercussions are far greater than one would expect them to be...

In short, are we like tomatoes?