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

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.

Epidemic cholera in Latin America, 1991-1993: implications of case definitions used for public health surveillance.

This report presents the various cholera case definitions used by the affected countries of Latin America, shows the numbers of cholera cases and deaths attributable to cholera (as reported by Latin American countries to PAHO through 1993), and describes some regional trends in cholera incidence. The information about how cholera cases were defined was obtained from an October 1993 PAHO questionnaire. In all, 948429 cholera cases were reported to PAHO by affected Latin American countries from January 1991 through December 1993, the highest annual incidences being registered in Peru (1991 and 1992) and Guatemala (1993). The case-fatality rate over the three-year period, and also in 1993, was 0.8%. A general downward trend in the incidence of cholera was observed in most South American countries, while the incidence increased in most Central American countries. A good deal of variation was noted in the definitions used for reporting cholera cases, hospitalized cholera cases, and cholera-attributable deaths. Because of these variations, broad intercountry comparisons (including disease burden calculations and care quality assessments based on case-fatality rates) are difficult to make, and even reported trends within a single country need to be evaluated with care. The situation is likely to be complicated in the future by the arrival of V. cholerae O139 in Latin America, creating a need to distinguish between it and the prevailing O1 strain. For purposes of simplicity, wide acceptance, and broad dissemination of case data, the following definitions are recommended: Confirmed case of O1 cholera: laboratory-confirmed infection with toxigenic V. cholerae O1 in any person who has diarrhea. Confirmed case of O139 cholera: laboratory-confirmed infection with toxigenic V. cholerae O139 in any person who has diarrhea. Clinical case of cholera: acute watery diarrhea in a person over 5 years old who is seeking treatment. Death attributable to cholera: death within one week of the onset of diarrhea in a person with confirmed or clinically defined cholera. Hospitalized patient with cholera:a person who has confirmed or clinically defined cholera and who remains at least 12 hours in a health care facility for treatment of the disease.

Correct case management of childhood diarrhea: a survey of nine state capitals in northeast Brazil.

The National Program for Maternal and Child Health (COSMI) of the Ministry of Health (MOH) of Brazil conducted a survey in nine state capitals from 29 March to 30 April 1993 to assess how well health facilities were managing diarrhea cases in patients under 5 years of age. One of seven PAHO/WHO health facility surveys performed in Latin America and the Caribbean in 1992-1993, the Brazilian survey took place in the Northeast Region where most diarrheal morbidity and mortality occur. Like the other six surveys, it used a new PAHO/WHO methodology designed to collect data on certain principal indicators through observation, interviews, and review of clinical records. Overall, 475 cases of patients with diarrhea were observed in 192 facilities, and 463 health workers and 474 caretakers were interviewed. The results indicated that few diarrhea patients received care that strictly followed the PAHO/WHO/Ministry of Health treatment guidelines. In terms of these guidelines, the correct procedure was used to assess the patient's hydration status only 8% of the time, and only 1% of the health workers provided correct advice to the caretaker on prevention and home care aspects of diarrheal diseases. The procedure used to rehydrate patients with oral rehydration salts (ORS) was correct in only 6% of the cases. Of those patients with bloody stools, 24% were treated appropriately with antibiotics. Besides collecting information on correct case management, the survey provided a basis for developing two-year operational plans of action in each of the nine participating states to strengthen efforts directed at controlling and preventing diarrheal diseases, including cholera.