Serological evidence of human infections with avian influenza viruses. Brief report

Two hundred ninety-four subjects from Milan were tested for serum hemagglutination-inhibiting (HI) and neuraminidase-inhibiting (NI) antibodies to five avian influenza viruses. No HI antibodies were found in all the serum samples. On the contrary, NI antibodies to each strain were detected depending on the year of birth of the subjects.