Epidemiology of hepatitis A in Valencia, Spain: public health implications

Between July 1988 and July 1989, sera from 1223 persons resident in the Valencia area of Spain were tested for antibodies against the hepatitis A virus. Sixty-five per cent of serum samples were positive for anti-HAV (95% confidence interval = 62.4-67.6). The prevalence of anti-HAV increased significantly with age (odds ratio > 50 years = 69.8; 95% confidence interval = 26.5-183.4) and previous history of hepatitis A (odds ratio = 2.1; 95% confidence interval = 1.4-3.2). Prevalence decreased with higher educational level (odds ratio, university studies = 0.2; 95% confidence interval = 0.1-0.5). Overall, there has been a reduction of anti-HAV prevalence reflecting the decreasing exposure of the Spanish population to hepatitis A virus in recent years, particularly in the younger generations. The age of infection has increased, increasing the probability of future epidemics in groups previously protected by immunity acquired in early childhood. This new epidemiological pattern has strong public health implications, and universal childhood vaccination together with measures directed to improve sanitation may be the best public health strategy to protect the population.