Citizens in western societies live in a relatively sterile environment, thanks to all the soaps, antiseptics, retuculated water and sewerage syatems, antibiotics, disinfectants etc that surround them. All these things carry a heavy oil subsidy and when the oil goes. . . so do they. City dwellers have little natural resistance to common pathogens found in nature because they've lived most of their lives detached from nature. These pathogens will return quickly once the toxic barriers listed above are removed.
City dwellers have little fear of germs, thanks to the hygene products they take for granted. Few have the knowledge of how to stay clean and keep their surroundings hygenic without them. Dog s**t on the footpaths won't just be a nuisance, it'll be a deadly health risk, especially when domestic pets aren't vetted (wormed etc.) any more. Lack of fuel for heating will encourage people to 'huddle' creating ideal conditions for epidemics like influenza and other nastier things to spread. Right when health services have fewest resources to deal with the problem.
Moving to a small, rural community is looking better all the time.
