Trash will pile up and no one will come pick it up. Some people will burn it and others wont care enough to. The waste will back up as well and some will bury it or burn it but others may not. Before long the little critters will start to appear. At first their wont be that many. Once they realize there is an abundance of food there will be more. With them these pests bring an incredible amount of disease. The black plague was spread by rats and cats.
In a survival situation you better have some answers for how you plan to deal with these creatures. There are many ways to deal with pests in our society today but in a world of mess and waste things could get much more complicated. This article will give you the tools to deal with them.