Read complete TAG report for 1994

HBV infection is a serious public health problem in the Americas. Patterns of HBV infection in this Region vary from low to very high endemicity levels. Low prevalence of HBV surface antigen (HBsAg) carrie state (0.1 to 1.0%) is found in temperate areas of North and South America, in parts of Middle America and the Caribbean, and in Mexico. Moderate levels of HBsAg (1.4 to 28%) are found in parts of tropical Middle and South America. Very high prevalence of HBsAg (5 to15%) occurs in the western parts of the Amazon Basin, in some Caribbean Islands (Hispaniola, and St. Kitts and Nevis), and in some areas of Brazil, Colombia, Peru and Venezuela. There are about 6.3 million chronic HBsAG Carriers int he Americas, of which 5.5. million live in Latin America and the Caribbean.

Fulminant hepatitis associated with delta infection has been documented in the Western Amazon and in certain areas of Colombia (e.g. Santa Maria, Uraba and Catatumbo areas), Venezuela (among the Yucpa-Bari Indians) and PEru (e.g. Abanacay, Quillabamba). Although scarce information is available on the impact due to the chronic consequences of HBV infection in Latin America and the Caribbean, it is likely proporcional to the level of disease endemicity and, in high endemicity areas, comparable to those in Africa and parts of Asia.

Vaccination is the most effective tool in preventing transmission of HBV. Vaccines are composed of the surface antigen of the hepatitis B virus (HBVsAg) and are produced by two different methods (plasma-derived or recombinant DNA). When administered properly, hepatitis B vaccine induces protection in about 95% of recipients. The plasma-derived vaccine is made from the blood of chronically infected individuals which has been treated to destroy any live virus. It has been shown to be safe and effective. Over 40 million doses have been given over a Lumber of years. Recombinant DNA vaccine is also safe and effective. It appears to be equal to the plasma-derived vaccine in every way. Two countries (Cuba and the United States) manufactured this type of vaccine in our Region.

Three doses of vaccine are considered a full course. In areas such as Latin America and the Caribbean where perinatal transmission of HBV is uncommon, the first dose may be given at six weeks (or later) with the first dose of DPT. The second and third doses should be time to coincide with visits required for other childhood immunizations. Several vaccine manufacturers are attempting to develop a quadrivalent DTP-HBV vaccine. It is believed that such a vaccine will be available for use in about 2-3 years. The availability of this vaccine will contribute significantly to the progress of the universal programs of HBV immunization of infants.

In general HBV immunization in Latin America has been directed towards areas of high HBV endemicity, particularly in those where outbreaks of fulminant hepatitis associated with delta infection have been recognized. Currently immunization demonstration programs are underway in several Latin American countries. One of the main objectives of these programs is to integrate HBV vaccine into EPI Schedule and it is expected that in the future these programs will be extended to all infants from these countries. Vaccination o folder children and health workers has also been implemented in certain areas. So far Cuba, Colombia, the United States and Brazil (in the Amazon Region) are the only countries in the Americas that are implementing universal infant immunization. Immunization of children is also being conducted selectively in other countries such as Venezuela, Costa Rica, Dominican Republic, Peru, and Honduras.