Active surveillance of avian influenza virus in backyard birds in Egypt

The lack of biosecurity measures for backyard birds in Egypt and their continuous contact with wild migratory birds make backyard birds much more vulnerable to avian influenza virus (AIV) than those on commercial farms. The wild bird-backyard flock pathway was claimed to be the source of the first intrusion of H5N1 virus in Egypt in February 2006. The Egyptian government reported the isolation of low-pathogenic AIV subtype H7 in migratory ducks from El-Abassa Lake, a fish-farming lake located 80 km east of Cairo. Fear of repeating the scenario of introducing H5N1 into the poultry sectors prompted us to survey backyard birds around the borders of the lake. Screening of 207 serum samples (73 from chickens, 67 from ducks, 52 from geese, 9 from turkeys, and 6 from pigeons) using a commercial generic anti-influenza A nucleoprotein antibody enzyme-linked immunosorbent assay revealed 4.9% positive chicken sera. No antibody against the AIV H7 subtype was recorded when a hemagglutination inhibition test was used, whereas 4.3% of the serum samples examined were positive for the H5 AIV subtype. Nevertheless, AIV was not detected in swabs examined by real-time reverse transcription-polymerase chain reaction. However, continuous surveillance of backyard birds should be emphasized.