Probably the first consideration in preventing the re-emergence of diseases that have vaccinations is to make sure both that the population levels of vaccinations remain high (above herd levels) and to monitor the effectiveness of the vaccines (and change them if they become less effective).

I thought you would receive more answers to this question - but let me add one more at this time.  A very important requirement to reduce both emerging and re-emerging pathogens is to prevent the acquisition of antibiotic resistance.  Once antibiotic resistance has been acquired, it creates situations where the infections are not stopped and then are passed to new individuals and and this begins a process which expands the prevalence of the disease.  Additional resistances expands the disease more.  A good example is tuberculosis in the U.S. - almost eradicated, but now many cases of highly resistant strains.