While widespread vaccination led to eradication of smallpox by 1979, a changed world and changing health priorities make it tougher to totally eliminate other infectious diseases, experts said at a AAAS meeting.

“Eradication of smallpox gave rise to a glow of optimism,” said Joshua Rosenthal, acting deputy director of the Fogarty International Center at the National Institutes of Health. If smallpox was gone, could measles, polio, and other diseases be far behind?