Surveillance for epidemic cholera in the Americas: an assessment.

In January 1991, epidemic cholera appeared in Peru and quickly spread to many other Latin American countries. Because reporting of cholera cases was often delayed in some areas, the scope of the epidemic was unclear. An assessment of the conduct of surveillance for cholera in several countries identified some recurrent problems involving surveillance case definitions, laboratory surveillance, surveillance methods, national coordination, and data management. A key conclusion is that a simple, well-communicated cholera surveillance system in place during an epidemic will facilitate prevention and treatment efforts. We recommend the following measures: a) simplify case definitions for cholera; b) focus on laboratory surveillance of patients with diarrhea primarily in the initial stage of the epidemic; c) use predominantly the "suspect" case definition when the number of "confirmed" cases rises; d) transmit weekly the numbers of cases, hospitalized patients, and deaths to regional and central levels; e) analyze data frequently and distribute a weekly or biweekly summary; and f) report the number of cholera cases promptly to the World Health Organization.