The lack of success in preventing and combating viral hepatitis (VH) is due to a number of objective difficulties, of which the most important are marked infectiousness of patients in the incubation period, two to three weeks or more before the appearance of jaundice; many, usually unrecognized, sources of the infection in patients with anicteric or asymptomatic forms of the disease and in carriers; inefficacy of anti-epidemic measures, due to their delayed application; and lack of specific preventive measures, owing to the fact that the etiologic agent has not yet been isolated.
Evidence from electron microscopic, immunological, biochemical, and epidemiological studies indicates that the Australia (Au) antigen is associated with the etiologic agent of hepatitis, especially the parenteral form.
Precise information on the epidemiology of VH, especially concerning cases of parenteral infection, is essential. Comparison of the findings in different countries is difficult, because reporting is often incomplete
Kurylowicz W. Epidemiology of Viral Hepatitis and its Long-Term Sequelae in Poland. Am J Dis Child. 1972;123(4):335-340. doi:10.1001/archpedi.1972.02110100067027