Thank you Mr. Chairman. I want to thank the congress organization, the ISID and the API for this kind invitation. My task today is to share with you some insights about the epidemiology of chronic hepatitis in Latin America.
Slide 2 Latin America is a sub-continental area of more than 21 million square kilometers with an estimated population of 569 million people, about 9.5% of the world population; it comprises 20 countries of Latin origin, where Spanish and Portuguese are spoken, but in the same region there are another 14 countries of non-Latin origins that share the same environment. It contributes with more than 5 trillion dollars a year to the Gross World Product.
Slide 3 Two main viruses produce chronic liver disease: the hepatitis B virus, a DNA virus belonging to the Hepadnavirus genus and the hepatitis C virus, a RNA virus of the Hepacivirus genus. Sometimes, co-infection of VHB with a third defective virus, the Delta agent, results in chronic infection or acute fulminant hepatitis.
Slide 4 I will show you some data about chronic hepatitis B in Latin America.
Slide 5 According to the WHO, the prevalence of VHB chronic carriers varies widely in different parts of the world. In Latin America we can find areas of low prevalence beside areas of very high prevalence, many times within the same country.
Slide 6 The great majority of countries have low prevalence and low risk of infection. Some other countries have intermediate prevalence and risk. High prevalence can be observed in the Amazon basin, affecting part of Colombia, Venezuela, north of Brazil and Peru. In these areas, the risk of infection is higher than 60%.
Slide 7 Prevalence of hepatitis B virus infection measured by anti-HBc antibodies can be as low as 0.6% in Chile and as high as 21.4% in Dominican Republic. Local epidemiological factors contribute to this variation, but there is a lack of more representative published data.
Slide 8 Past or current infection, measured by the prevalence of anti-HBc, plotted according to age intervals, reveals in some countries, like Dominican Republic, Argentina, Brazil and Venezuela, a little bit higher prevalence in infant and children below 10 years old. Except for Dominican Republic, the prevalence falls in older than 10 years old children and teenagers, rising again in young adults. This reflects two types of VHB transmission: perinatal and sexual. In all countries prevalence of infection is higher with increasing age.
Slide 9 Prevalence of chronic infection can be very low, like in Chile or reach higher values, like in Brazil Colombia and Venezuela. Unfortunately, current data is lacking for many countries.
Slide 10 In Brazil, a continental sized country, with many different regions, environments, populations and cultures, the prevalence of chronic VHB infection can be lower than 1% in the oriental side. In the Amazon basin prevalence is higher. Risk factors are age, male sex, having initiated sexual life, past history of blood transfusion and drug abuse, along with lower socio-economical level. Higher education is a protection factor.
Slide 11 Genotypes distribution pattern is related to colonization routes of the first humans that entered America through the Behring peninsula, about 20.000 years ago. Two main routes spread this population to the south of the continent, as can be seen here by the F genotype distribution. F1 goes by the west coast and genotype F2 goes by the east, meeting in Argentina. Other genotypes came later, with the slave traffic and migration from Europe and Asia. Genotypes F is typical Amerindian and genotype H is derived from F and exist mainly in Central America. In many countries, like Brazil and Argentina, genotype A is predominant, followed by genotypes D and F.
Slide 12 The F genotype divides in clusters with well defined distribution. F1 clusters Ia and Ib exist in Central America and spread to the south, until Argentina through the west coast. F2 clusters II, III and IV can be found in the east coast of Central America, the north and centre of South America. This patterns can mix and change because of migration.
Slide 13 A few words about Delta virus co-infection. The Amazon basin is considered an area of high prevalence, reaching Brazil and Peru, together with the north part of Venezuela and Colombia, where Amerindian population is highly affected. In the south part of Brazil, co-infection is a rare event and cases are imported from the north.
Slide 14 Now I’m going to talk about chronic hepatitis C
Slide 15 As you can see in this map, statistics of the WHO are five years lagged, but still reflect the magnitude of the problem. Latin America is considered a low prevalence zone, as compared with other regions of the world. Less than 2% of the population is affected or something like 10 million people.
Slide 16 Seroprevalence data is incomplete and in many countries is based in blood bank studies, which have population selection bias. A feel population studies in Chile, Brazil and Colombia confirm the WHO estimates. Considering a mean prevalence of 1.2%, almost 7 million people is affected with chronic hepatitis C in Latin America.
Slide 17 In Brazil, a feel studies revealed variable numbers, with antibodies to VHC prevalence varying between 0.22 to 2.61%. A major seroprevalence study in Sao Paulo city showed a mean prevalence of 1.42% for antibodies. The RNA prevalence is low, but this result is biased by the small sample size.
Slide 18 In Brazil, until 2005, there were a little bit more than 50,000 cases of chronic hepatitis C reported to the health authorities. This represents less than 2.5% of estimated existing cases. This means that a great number of people are infected with HCV without knowing. These individuals are at risk of developing cirrhosis and hepatocarcinoma. There is a repressed demand for diagnosis and treatment in Brazil and this situation can occur in other countries of Latin America. As the disease affects millions of people and treatment is expensive, health expenses forecast is of great concern, mainly for developing countries with many other endemic health problems.
Slide 19 VHC genotype distribution follows the American and European pattern: genotype 1 is more frequent, being almost 70% of isolates, followed by genotype 3 and 2. Other genotypes, like 4 or 5 can be isolated occasionally.
Slide 20 Thank you for the attention.
