Investigations on infection status with H5 and H7 avian influenza virus in short-distance and long-distance migrant birds in 2001.

The role of migrating birds as potential vectors for avian influenza virus (AIV) was investigated. We captured 543 migrating passerines during their stopover on the island of Helgoland (North Sea) in spring and autumn 2001. These birds were sampled for avian influenza A viruses (AIV), specifically the subtypes H5 and H7. For virus detection, samples were taken from 1) short-distance migrants, such as chaffinches (Fringilla coelebs; n = 131) and song thrushes (Turdus philomelos; n = 169); and 2) long-distance migrants, such as garden warblers (Sylvia borin; n = 142) and common redstarts (Phoenicurus phoenicurus; n = 101). Virus isolation assays failed to identify AIV. Therefore, regarding the actual low number of samples, we speculate that the tested four species of passerines were not infected by AIV, indicating that the passerine species examined in this study may play only a minor role as potential vectors of AIV.

No detection of avian influenza A viruses of the subtypes H5 and H7 and isolation of lentogenic avian paramyxovirus serotype 1 in passerine birds during stopover in the year 2001 on the island Helgoland (North Sea).

A total of 543 migrating passerines were captured during their stopover on the island of Helgoland (North Sea) in spring and autumn 2001. They were sampled for the detection of avian influenza A viruses (AIV) subtypes H5 and H7, and for avian paramyxoviruses serotype 1 (APMV-1). The goal of the study was to examine the role of migrating birds as potential vectors for these zoonotic viral diseases. For virus detection samples were taken from a) short-distance migrants such as chaffinches (Fringilla coelebs, n = 131) and song trushes (Turdus philomelos, n = 169), and b) long-distance migrants such as garden warbler (Sylvia borin, n = 142) and common redstarts (Phoenicurus phoenicurus, n = 101). Virus detection was done on conjunctival, choanal cleft and cloacal swabs. Embryonated SPF chicken eggs were used to isolate and propagate virus followed by virus identification in a hemagglutination test, hemagglutination inhibition test and in an agar gel diffusion test. In none of the tested samples AIV was detected. Therefore, we conclude that the tested four species of passerines were infected by these pathogens. Six out of 543 birds (1.1 %) were found to carry non-pathogenic and lentogenic strains of APMV-1. This indicates that the passerine species examined in this study may play only a minor role as potential vectors of APMV-1.