Are there national risk factors for epidemic cholera? The correlation between socioeconomic and demographic indices and cholera incidence in Latin America

Abstract

Background: From 1991 through 1995, all Latin American countries maintained cholera surveillance systems to track the epidemic that entered the region through Peru in January 1991. These data were used to assess correlations between socioeconomic and demographic indices that might serve as national risk predictors for epidemic cholera in Latin America.

Methods: Correlations between country-specific cumulative cholera incidence rates from 1991 through 1995 and infant mortality, the Human Development Index [HDI] a numerical value based on life expectancy, education, and income), gross national product (GNP) per capita, and female literacy were tested using the Pearson correlation coefficient.

Results: A total of 1,339,834 cholera cases with a cumulative incidence rate of 183 per 100,000 population were reported from affected Western Hemisphere countries from 1991 through 1995. Infant mortality rates were the most strongly correlated with cumulative cholera incidence based on the Pearson correlation coefficient. The HDI had a less strong negative correlation with cumulative cholera incidence. The GNP per capita and female literacy rates were weakly and negatively correlated with cholera cumulative incidence rates.

Conclusions: Infant mortality and possibly the HDI may be useful indirect indices of the risk of sustained transmission of cholera within a Latin American country. Cumulative cholera incidence is decreased particularly in countries with infant mortality below 40 per 1000 live births. The lack of reported cholera cases in Uruguay and the Caribbean may reflect a low risk for ongoing transmission, consistent with socioeconomic and demographic indices. Cholera surveillance remains an important instrument for determining cholera trends within individual countries and regions.

PIP: To track a cholera epidemic that entered Latin America through Peru in January 1991, the region maintained cholera surveillance systems from 1991 through 1995. The present study used the surveillance data to identify socioeconomic and demographic indices that might serve as national risk predictors for epidemic cholera in Latin America. A total of 1,339,834 cholera cases, with a cumulative incidence rate of 183/100,000 population, were reported in 1991-95 from 22 countries in the region. Use of the Pearson correlation coefficient indicated that infant mortality rates were most strongly associated with cumulative cholera incidence. Cumulative cholera incidence was decreased in countries with an infant mortality below 40/1000 live births. The Human Development Index had a less strong negative correlation with cholera incidence, but values under 0.720 may provide an additional estimator of risk. The gross national product per capita (above US$2000) and female literacy rates above 90% were weakly and negatively correlated with cholera cumulative incidence rates. The continued lack of cholera cases in the Caribbean, where most countries have socioeconomic and demographic indices that resemble the Latin American countries with lowest risk for cholera, provides tentative support for this framework.