Prevalence of Hepatitis A Virus Antibody in Portuguese Travelers: A New Paradigm

Introduction: In Portugal, the prevalence of hepatitis A virus infection has decreased in the past decades, especially in young adults. The aim of this study was to detect the prevalence of antibody to hepatitis A virus in a population observed in our Travel Clinic.
Material and methods: Antibodies against hepatitis A, hepatitis B, hepatitis C and human immunodeficiency virus were tested using standard enzyme immunoassay in patients older than 18. The exclusion criteria were: prior vaccination for hepatitis A virus, previous diagnosis of infection with hepatitis B virus, hepatitis C virus and/or human immunodeficiency virus, foreign travelers and long-term expatriates. We applied an epidemiological survey and data was statistically analyzed with SPSS® 18.0.
Results: In the 665 travelers studied, natural immunity to hepatitis A virus was present in 57.6% (n = 383). They were stratified into 8 age groups and for each one hepatitis A immunity was clarified: 5.0% (n = 1) in 18 – 25 years, 32.3% (n = 21) in 26 – 30 years, 40.9% (n = 47) in 31 – 35 years, 45.8% (n = 54) in 36 – 40 years, 68.7% (n = 79) in 41 – 45 years, 70.1% (n = 68) in 46 – 50 years, 80.8% (n = 63) in 51 – 55 years and 87.7% (n = 50) over 56 years old. In those who accepted further screening, positivity for hepatitis B core antibody was found in 0.6% (n = 3) travelers, hepatitis C virus infection in 1.1% (n = 6) and human immunodeficiency virus infection in 0.5% (n = 3) whose previous status was unknown. The most frequent travel destination was sub-Saharan Africa (72.6%; n = 483).
Discussion: We found 49.1% (n = 260) travelers under 50 years old susceptible to hepatitis A virus infection and for those between 40 and 50 years, 30.7% (n = 65) still need vaccine protection.
Conclusion: Across age groups there is a trend towards lower prevalence of hepatitis A virus antibody, in particular among youngsters, when compared with older Portuguese studies.