To dream of a plague represents broad issues that negatively effect a lot of people around you. A decision or situation has had large-scale negative consequences. Shared suffering or a problem that nobody you know ever seems to find a solution for. A sense of hopelessness that nothing can be done about a problem.
Alternatively, a plague may represent different areas of your life that are negatively impacted by the same problem that has no solution in sight.
Dreams about the plague may also reflect your feelings about other people being hopelessly impossible to help. Feeling that it's better to abandon people than to succumb to a problem yourself. Fearing losing every single thing you have worked for to an unstoppable problem. Guilt for abandoning people you can't help during a crisis moment.
To dream of becoming infected with the plague may represent feelings about yourself being hopelessly failed or that you can do nothing except make a problem worse. A fear of your hopeless problems contaminating other people's lives.