Levine R J, Khan M R, D'Souza S, Nalin D R
Lancet. 1976 Jul 10;2(7976):84-6. doi: 10.1016/s0140-6736(76)92298-4.
A review of the incidence of cholera from 1964 through 1974 in Matlab, Bangladesh, revealed that among the villages several had very high incidence-rates. Investigation indicated that high cholera-rates in two of these villages were probably related to water contamination from a nearby cholera hospital established in 1963. The data imply that heavy contamination can overcome any immunity resulting from repeated exposure.