Yup, smallpox was the first disease to be eradicated through vaccination. Guinea-worm disease, which is caused by a parasite, is close to eradication, but there's no vaccine, it's being eradicated by implementing safe drinking water and teaching people how to avoid it. Once it dies out it will be the first parasitic disease to be eradicated without vaccine or cure (pretty amazing). The guinea worm relies on humans as part of its life cycle, it HAS to pass through it's human-reliant phase every year, so once everyone stops getting it it will die out.

Polio is being eradicated by vaccine. The main obstacles to eradication are under-reporting (in remote areas where there are no doctors so those with polio see no-one who could report and implement vaccination), conflict (when areas become wartorn Unicef and the Red Cross, who are key players in the WHO's work on vaccination of populations, often have their vaccination programme's interrupted). The WHO has marked measles for eradication in the USA by 2010, but because of parents declining the vaccine it's unlikely now that they'll hit that target. Many of the diseases still in existence today would have been eradicated by now if every person who could have been vaccinated had been.

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