I've had them all. You might say I'm prone to these infections. Only recently though, have I learned how devastating they are to my spiritual health. They sap vigour, destroy motivation, kill joy, poison the environment, and infect others. One of the most disturbing things is that generally speaking, they consume a lot of energy, yet build nothing.
Negativity tends to disagree with or oppose that which is considered positive or constructive.
Simply, we become absorbed with what we don't like about what others are doing instead of with what we do like about what we're doing. The key idea here is opposition. We are against. We launch our attack against our comrades in arms instead of at the enemy. The antidote to negativity is to start doing something yourself.