Antacid consumption markedly lowers the infective dose. Cholera can be confirmed only by the isolation of the causative organism from the diarrheic stools of infected individuals. Cholera is generally a disease spread by poor sanitation, resulting in contaminated water supplies. This is clearly the main mechanism for the spread of cholera in poor communities in South America. The excellent sanitation facilities in the U.S. are responsible for the near eradication of epidemic cholera.
Sporadic cases occur when shellfish harvested from fecally polluted coastal waters are consumed raw.
Cholera may also be transmitted by shellfish harvested from nonpolluted waters since V. cholerae O1 is part of the autochthonous microbiota of these waters. Fewer than 80 proven cases of cholera have been reported in the U.S. since 1973. Most of these cases were detected only after epidemiological investigation. Probably more sporadic cases have occurred, but have gone undiagnosed or unreported. The illness is generally self-limiting.