Active surveillance in poultry in Poland for avian influenza subtypes H5 and H7

A serological surveillance programme for avian influenza A virus (AIV) subtype H5 and H7 in poultry was implemented in Poland in 2008-2013 with two main objectives: i) to detect subclinical infections or previous exposures to AIV H5 and H7 subtypes and ii) to demonstrate the AI- free status of Poland. During this period, over 45 000 serum samples from 2833 holdings were examined using the hemagglutination inhibition test (HI). The presence of HI antibodies was detected in 8 breeder geese holdings (7 positive for H5 and 1 positive for H7 AIV) and in 1 breeder duck holding (H5-positive), which represented 0.32% of all investigated holdings. All seropositive flocks were examined by real time RT-PCR with negative results, which substantiated the AI-free status of Poland. Positive results detected in clinically healthy poultry kept in an open range system indicate prior infections with low pathogenic AIV originating from the wild-bird reservoir.