Fall 1996 Volume 1, Number 3		Hepatitis A: special risk for Hispanic populations For decades, hepatitis A has caused significant morbidity in some U.S. Hispanic communities, despite handwashing campaigns and the administration of immunoglobulin to case contacts. With the availability of two hepatitis A vaccines in the U.S., some communicable disease directors in California, Texas, and other southwest border states are beginning to feel optimistic about the prospect of finally controlling hepatitis A in the Hispanic population. National data indicate higher risk for Hispanics National surveillance data indicate that Hispanics have a higher risk for HAV infection than non-Hispanics. In a 1992 study, CDC epidemiologist Dr. Craig Shapiro and colleagues used data from the agency's Viral Hepatitis Surveillance Program (VHSP) to calculate a national incidence rate of 17.6 per 100,000 in persons of Hispanic ethnicity, versus a rate of 7.5 per 100,000 in non-Hispanics, a more than two-fold difference. In an earlier study, Dr. Shapiro compared the hepatitis A incidence rate in U.S. counties with a high Hispanic population (Ñ15%) with counties with a lower Hispanic population (<15%). Counties having a high Hispanic population had an incidence rate that averaged 2.1 times higher than counties having a lower Hispanic population. Hispanics are also over-represented in travel-related hepatitis A cases. In 1993, 47% of international travel-related hepatitis A cases reported to VHSP occurred in Hispanics, although only 12% of all VHSP cases occurred in that group. Among all the travel-related cases, 67% were associated with travel to Mexico and Central or South America. National serologic surveys also show a higher infection risk for Hispanics. In the NHANES III serosurvey conducted during 1989‚1991, anti-HAV prevalence in Mexican-Americans was 67%, compared to 37% for blacks and 29% for whites. Example ã San Antonio, Texas San Antonio, Texas is typical of the hepatitis A situation in many areas near the U.S.-Mexico border. There, hepatitis A incidence averages 20‚30 per 100,000 population, about two to three times the national rate. In 1995, of all cases occurring in San Antonio, 81% occurred in persons of Hispanic ethnicity, although only 56% of the population was Hispanic. The disease is concentrated in central San Antonio in an area of poor, crowded neighborhoods. The transmission of hepatitis A in such areas has not been highly studied, but many epidemiologists in border areas believe that local hepatitis A cases are related to travel to and from areas south of the U.S.-Mexico border, where hepatitis A infection occurs at high rates. Although reliable disease statistics from Mexico are sparse, anecdotally hepatitis A is thought to be highly endemic in some areas (where most of the population is infected asymptomatically before age 5) and periodically epidemic in other areas, including some areas near the U.S. border. Roger Sanchez, communicable disease epidemiologist at the San Antonio Metropolitan Health District, hypothesizes that, in his city, the disease mainly affects second- and third-generation Hispanic immigrant families. "It's probably not the immigrants themselves who face the highest risk. Actually, we expect them to be mainly immune to hepatitis A. It's their U.S.-born children, grandchildren, and other family members who face the highest risk," Sanchez said in a recent interview. "The second- and third-generation kids grow up in the U.S., where living conditions are better. They are unlikely to be infected when they are toddlers. As a result, hepatitis A tends to occur here in older children, ages 5‚15. Most of the infections seem to occur in these children when they are exposed to HAV during contact with young relatives from south of the border," said Sanchez. "Interestingly, later generations of Hispanic immigrants have low incidence rates of hepatitis A, probably because they are better off socio-economically and because they have less contact with relatives south of the border," he said. California In much of southern California, hepatitis A is endemic and occurs at a significantly higher rate in the Hispanic population than in other groups. Within the Hispanic population, the risk lies almost entirely in children, especially in the 5‚9 age group. In older Hispanic people (age > 15), the incidence rate is generally no higher than for non-Hispanic adults. In Los Angeles County during 1994, for example, Hispanic children age 5-9 had a hepatitis A incidence rate of 86.2 per 100,000. The rate did not exceed 20 per 100,000 in any other age or ethnic/racial category. Age-specific incidence rates for whites peaked in the 25- to 34-year-old group at 16.0 per 100,000. The rates for Asians peaked in the 20- to 24-year old group at 10.6 per 100,000, and the rates for African-Americans peaked in the 35- to 44-year age group at 13.3 per 100,000 (data from Los Angeles County 1994 Communicable Disease Morbidity Report). Plans for control Dr. Fernando A. Guerra, director of the San Antonio Metropolitan Health District and a member of ACIP (see Note to Readers) believes that hepatitis A can eventually be controlled in the Hispanic population. "It will be a number of years before hepatitis A vaccine will be given routinely to all babies in the U.S." he said recently, reflecting ACIP's policy. "But we don't have to wait until then to begin controlling the disease in our Hispanic population and other high-risk groups. Hepatitis A, like many other diseases, is related to the movement of people across the bi-national border. We need to make people aware of the risk." In a February 1996 "Dear Colleague" letter to state immunization directors, CDC Hepatitis Branch Chief, Dr. Harold S. Margolis, and National Immunization Director, Dr. Walter A. Orenstein, relayed the decision of ACIP to recommend routine hepatitis A vaccination for children beginning at age 2 in "high-rate communities." The definition of "high-rate communities" includes American Indian and Alaskan Native communities (see HCR April 1996), but also "some communities on the U.S.-Mexico border with predominantly Hispanic populations, especially those with sub-standard housing, water and/or sanitation ... if supported by local surveillance or other epidemiologic data." CDC urged state policy makers to identify high rate communities, and begin to develop programs to ensure implementation of vaccination of children. Control programs are underway or planned in a few areas of Texas and southern California. Dr. Guerra has designed a 5-year demonstration project to control hepatitis A in the inner-city of San Antonio. The project will vaccinate schoolchildren, both Hispanic and non-Hispanic, in 27 high-incidence census tracts, through freestanding and school-based clinics. The vaccine will be supplied under the federal Vaccines for Children program. The effectiveness of the project will be evaluated through San Antonio's existing immunization registry and disease surveillance systems. The State of Texas is considering a vaccination program in communities along the U.S.-Mexico border, called colonias, where hepatitis A occurs at elevated rates. Some colonias lack basic infrastructure such as water and sewage systems, and many of their residents work on farms, traveling frequently across the bi-national border. Texas is conducting serosurveys in these areas to help aim vaccination efforts. "The strategy for controlling hepatitis A in these communities is similar to the one we are using to control polio ã widespread catch-up immunization of young, susceptible children followed by routine immunization of infants and toddlers," said CDC's Dr. Margolis recently. "Significantly reducing the incidence of hepatitis A in these communities is an attainable public health objective."