Wave upon wave of diseaseThe cholera pathogen,Vibrio cholerae, is considered to be ubiquitous in water systems, making the design of eradication measures apparently fruitless. Nevertheless, local and globalVibriopopulations remain distinct. Now, Weillet al.and Dommanet al.show that a surprising diversity between continents has been established. Latin America and Africa bear different variants of cholera toxin with different transmission dynamics and ecological niches. The data are not consistent with the establishment of long-term reservoirs of pandemic cholera or with a relationship to climate events.Science, this issue p.785, p.789