A traditional practice in the dry coastal plain is to use sewage to fertilize fields when water is scarce. The farmers need to grow the kind of crops that have high cash yields and short growing seasons, and these are often vegetables that are eaten raw. A local dish called seviche, which is raw fish and is a national favorite was particularly denounced. However, further studies indicated no correlation. The fish is marinated in lemon and other acidic substances that kill the vibrio.
Cholera is an infection associated with poverty.
This fact represents another factor in explaining the epidemic proportions reached in this and other Latin American countries. Cholera was detected in the Peruvian population near the beginning of 1991, brought to the country perhaps from the bilge water of a Chinese freighter. This phenomenon takes place at the end of December and the beginning of January. In 1991, this current produced a higher temperature than usual in that part of the Pacific Ocean. According to Rita Colwell at the University of Maryland, when a vibrio is submerged in cold water it can shrink to be 300 times smaller than its usual size.