With regard to the role of wild ducks and coots as a source of viruses potentially pathogenic for domestic poultry we observed some differences: in coots, no evidence of H5 and H7 virus circulation was found either at serological or virological level whereas ducks serologically positive to H5 virus were detected every year. In the present study, the highest H5 antibody frequencies that were observed in DWMA during the first sampling period overlapped with the H5N2 Italian poultry epidemic (Donatelli et al., 2001). Moreover, even if no H5 viruses were isolated during the present study period, seroconversion observed in a mallard indicated that circulation of H5 subtype viruses occurred in the sampling area during the first sampling period (Table 2). Unlike H5 AIVs, no evidence of H7 virus circulation was found either at serological or virological level in ducks trapped in the area under study (Table 1). Thus it appears that no H7 viruses circulated among ducks sampled in the study area since 1992 (De Marco et al., 2004). In particular, duck sera resulted negative for H7 subtype both before and after the beginning of the catastrophic Italian poultry epidemic due to the H7N1 serovar (Capua & Alexander, 2004), suggesting a possible implication of other bird reservoirs. With regard to virus circulation, the H1N1 subtype appears to be endemic in Italian wetlands since 1992 (De Marco et al., 2004). H2N3 and H11N6 strains were isolated for the first time, even though ducks serologically positive to both subtypes had been found in previous years in the same study area (De Marco et al., 2004). The present results, together with data obtained before and after this study period in the same study area (De Marco et al., 2004, Campitelli et al., 2004b), suggest a perpetuation of H5 AIVs in the wild duck reservoir in Italy. This evidence is all the more relevant when we consider that the duck populations we analysed are representative of waterfowl populations that very likely make use of wetlands of Northern Italian regions (where H5N2, H7N1 and H7N3 poultry epidemics occurred in recent years) during their migrations northward in spring and southward in autumn (De Marco et al., 2000). The identification in 2001, in these wetlands, of H7N3 duck viruses almost identical to H7N3 strains affecting domestic poultry in Northern Italy in 2002-03 (Campitelli et al., 2004a) supports the existence of an epidemiological connection between these two areas and confirms the importance of maintaining an active influenza surveillance program in wild waterfowl reservoirs.
De Marco M. A., Foni E., Campitelli L., Delogu M., Raffini E., Chiapponi C., et al. (2005). Influenza virus circulation in wild ducks and coots in Italy during H5N2 and H7N3 poultry epidemic periods (1998- 1999). BASEL : KARGER.
Influenza virus circulation in wild ducks and coots in Italy during H5N2 and H7N3 poultry epidemic periods (1998- 1999)
De Marco M. A.;DELOGU, MAURO;
2005
Abstract
With regard to the role of wild ducks and coots as a source of viruses potentially pathogenic for domestic poultry we observed some differences: in coots, no evidence of H5 and H7 virus circulation was found either at serological or virological level whereas ducks serologically positive to H5 virus were detected every year. In the present study, the highest H5 antibody frequencies that were observed in DWMA during the first sampling period overlapped with the H5N2 Italian poultry epidemic (Donatelli et al., 2001). Moreover, even if no H5 viruses were isolated during the present study period, seroconversion observed in a mallard indicated that circulation of H5 subtype viruses occurred in the sampling area during the first sampling period (Table 2). Unlike H5 AIVs, no evidence of H7 virus circulation was found either at serological or virological level in ducks trapped in the area under study (Table 1). Thus it appears that no H7 viruses circulated among ducks sampled in the study area since 1992 (De Marco et al., 2004). In particular, duck sera resulted negative for H7 subtype both before and after the beginning of the catastrophic Italian poultry epidemic due to the H7N1 serovar (Capua & Alexander, 2004), suggesting a possible implication of other bird reservoirs. With regard to virus circulation, the H1N1 subtype appears to be endemic in Italian wetlands since 1992 (De Marco et al., 2004). H2N3 and H11N6 strains were isolated for the first time, even though ducks serologically positive to both subtypes had been found in previous years in the same study area (De Marco et al., 2004). The present results, together with data obtained before and after this study period in the same study area (De Marco et al., 2004, Campitelli et al., 2004b), suggest a perpetuation of H5 AIVs in the wild duck reservoir in Italy. This evidence is all the more relevant when we consider that the duck populations we analysed are representative of waterfowl populations that very likely make use of wetlands of Northern Italian regions (where H5N2, H7N1 and H7N3 poultry epidemics occurred in recent years) during their migrations northward in spring and southward in autumn (De Marco et al., 2000). The identification in 2001, in these wetlands, of H7N3 duck viruses almost identical to H7N3 strains affecting domestic poultry in Northern Italy in 2002-03 (Campitelli et al., 2004a) supports the existence of an epidemiological connection between these two areas and confirms the importance of maintaining an active influenza surveillance program in wild waterfowl reservoirs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
