A new model for evaluating a potential new strategy in the fight against drug-resistant diseases has been developed by experts. The strategy would take advantage of parasite refugia–host populations not treated with drugs, thereby serving as ‘safe zones’ where parasites don’t develop drug resistance. When parasites from refugia mix with their drug-resistant counterparts in the general population, they could reduce the incidence of drug-resistance overall, which may help prolong a drug’s effectiveness, say the researchers.