Hepatitis A in Latin America: a changing epidemiologic pattern.

Abstract

Abstract. In a multicenter study, hepatitis A virus (HAV) seroprevalence was surveyed in six countries in Latin America in which in 12,000 subjects were stratified for age. The highest rates of seroprevalence were recorded in the Dominican Republic (89.0%) and Mexico (81.0%), with lower rates in Brazil (64.7%), Chile (58.1%), Venezuela (55.7%), and Argentina (55.0%). The seroprevalence of HAV in children between 1 and 5 years of age was less than 50%, except in the Dominican Republic. In the 5-10-year-old age group, seroprevalence rates have also decreased compared with previous reports. This suggests that the epidemiology is shifting from high to intermediate endemicity, with the population susceptible to HAV infection shifting from children to adolescents and adults. Furthermore, data from Brazil, Argentina, and Mexico show that HAV seroprevalence is significantly lower in people living in medium and high socioeconomic conditions. This study suggests the need for appropriate vaccination programs to be implemented targeting children, adolescents, and adults, particularly in higher socioeconomic groups.Hepatitis A virus (HAV) has a worldwide distribution and is the most frequent etiologic agent in cases of viral hepatitis in Latin America.

The epidemiology of hepatitis A in Rio de Janeiro: environmental and domestic risk factors

“…These studies have found patterns of prevalence of antibodies to hepatitis A virus, which depend on the local environmental conditions and standard of living of the study population [4,5]. These patterns fit broadly into three groups -of high, medium and low endemicity -which each have different implications for intervention strategies [6].…”

“…Low endemicity is found in the relatively well-off areas of large cities where water supply and domestic hygiene have reached adequate levels, while high endemicity persists in the lowincome urban periphery and rural areas. Studies from Latin America have usually found this mixed pattern [6]. In the first, low prevalence group, the main intervention strategy is immunization of specific groups or of the general population.…”

Cost-effectiveness of childhood hepatitis A vaccination in Argentina: a second dose is warranted

“…Because no nationwide seroprevalence study has been conducted with a sample size adequate for stratification by region and age, hepatitis A seroprevalence was estimated based on reports from areas with below-average (26)(27)(28), average (10,29,30) and aboveaverage (31, 32) infection rates, compared with Argentina as a whole. The Northeast and Central regions were considered to have below-average endemicity, the South region had average endemicity, and the Cuyo and Northwest regions had above-average endemicity.…”

“…A United States model of intrahousehold transmission (33) was adapted to Argentina to account for larger household sizes (34), higher rates of hepatitis A immunity (10,(26)(27)(28)(29)(30)(31)(32), and more recent data on agespecific probabilities that hepatitis A infections will cause overt disease (4). The model predicts the number of secondary cases resulting from personal contact with individuals infected with hepatitis A based on household size, age distribution, and age-specific probabilities of having hepatitis A immunity.…”

“…Thus, vaccine recommendations developed for lower endemicity regions are inappropriate (8). Hepatitis A endemicity is declining in Argentina, as in much of Latin America (9,10). Seroprevalence among children 11 to 15 years old is 54% (9), so by adolescence, nearly half the population lacks immunity from a common disease that causes substantial medical and work loss costs (5,11).…”