Bangladesh paid villagers to find smallpox cases

By the early 1970s the global smallpox eradication campaign had shifted from mass vaccination to a 'search and containment' strategy: find every active case fast, ring-vaccinate everyone around it, and stop transmission before it spread further.

More searchers and more search rounds were the obvious lever, and the program kept adding both, but government searchers were also outsiders asking villagers to hand over information families sometimes had reason to conceal. The people best positioned to know when a case appeared — neighbors, market vendors, boatmen, relatives — had no stake in telling a stranger with a vaccination kit, and the program's own accountability rules made things worse: vaccinators were being penalized for outbreaks discovered in their assigned area, which quietly rewarded them for not looking too hard.

Paid any citizen a cash reward for reporting a confirmed case, turning neighbors who already knew into a real-time surveillance network official teams could not match.

Villagers already knew about cases, but had no reason to tell outsiders.

Cash rewards gave neighbors a stake in reporting, overcoming concealment.

The reward scaled surveillance to the whole population, far beyond any search team.

Removing penalties on vaccinators stopped them from ignoring outbreaks.

When official monitors can't see a problem, pay the people who already can — they become cheap, real-time detection.

Bangladesh recorded the world's last endemic variola major case in 1975, and smallpox was certified eradicated there the next year. The reward-driven surveillance model, alongside the removal of vaccinator penalties for reported outbreaks, became a template cited in WHO's global eradication history and in later disease-surveillance design, where crowdsourced case reporting from the public is now standard practice for polio, Ebola and other outbreak responses.