[Serological diagnosis of hepatitis A: determination with the RIA of anti-A specific IgM after absorption of IgG with protein A of Staphylococcus aureus].

The research of specific IgM anti virus A (anti HAV-IgM), by absorbtion of IgG with Staphylococcus aureus A protein, has been conducted in the sera of 49 patients with acute hepatitis non B (HBsAg negative). Twenty-nine of these patients (59.2%) were anti HAV-IgM positive and therefore were diagnosed as viral hepatitis A, while twenty (40.8%) were anti HAV-IgM negative and were considered as non A-non B hepatitis. In the present work the practical utility of the detection specific IgM by absorbtion with A protein is discussed also in respect of the more expensive and less sensitive technique of gel fractionation of the sera. In addition our preliminary results document a decreasing incidence of viral hepatitis A in all the cases seen in the period 1978-1979. This event, which needs further investigations, could also be due to a more significant incidence of non A-non B hepatitis, probably as consequence of increasing drug-addiction.