An Occurrence of Avian Influenza Virus Infection in Laying Chickens

Abstract

The isolation of avian influenza virus from chickens is reported for the first time in the United States since the fowl plague outbreak of 1929. The type-A virus was isolated from commercial Leghorn laying hens between 54 and 55 weeks old and involved three different farms in north-central Alabama. These flocks experienced up to 69% mortality and a severe decrease in egg production within a 14-day period.

The onset of virus shedding and clinical signs in chickens infected with high-pathogenicity and low-pathogenicity avian influenza viruses

“…Mild cyanosis of the comb and wattles was also reported in some birds during this time. Huddling and depression, followed within hours by the first deaths, were seen during a severe H4N8 outbreak in layers in Alabama (Johnson & Maxfield, 1976). Decreased egg production, cyanotic combs, and some diarrhoea were also reported.…”

“…Although marked clinical signs are possible (Johnson & Maxfield, 1976;Johnson et al, 1977;Brugh et al, 1996;Swayne et al, 1997;Bano et al, 2003;Nili & Asasi, 2003), most LPAI viruses tend to cause disease when chickens are co-infected with other pathogens or are subject to environmental stresses (Hooper & Selleck, 1998;Bano et al, 2003;Nili & Asasi, 2003). Clinical signs reported in infected chickens include depression/lethargy, decreased feed and water consumption, decreased egg production, decreased fertility and hatchability of eggs, misshapen eggs, and increased mortality (Johnson & Maxfield, 1976;Alexander & Stuart, 1982;Bean et al, 1985;Hooper & Selleck, 1998;Ziegler et al, 1999;Kinde et al, 2003;Mutinelli et al, 2003;Nili & Asasi et al, 2003;Bowes et al, 2004;Swayne & Pantin-Jackwood, 2006). Respiratory signs including cyanosis and facial oedema, conjunctivitis, and diarrhoea have been reported at times in some infected flocks (Johnson & Maxfield, 1976;Hooper & Selleck, 1998;Ziegler et al, 1999;Kinde et al, 2003;Mutinelli et al, 2003;Nili & Asasi, 2003;Swayne & Pantin-Jackwood, 2006).…”

“…Clinical signs reported in infected chickens include depression/lethargy, decreased feed and water consumption, decreased egg production, decreased fertility and hatchability of eggs, misshapen eggs, and increased mortality (Johnson & Maxfield, 1976;Alexander & Stuart, 1982;Bean et al, 1985;Hooper & Selleck, 1998;Ziegler et al, 1999;Kinde et al, 2003;Mutinelli et al, 2003;Nili & Asasi et al, 2003;Bowes et al, 2004;Swayne & Pantin-Jackwood, 2006). Respiratory signs including cyanosis and facial oedema, conjunctivitis, and diarrhoea have been reported at times in some infected flocks (Johnson & Maxfield, 1976;Hooper & Selleck, 1998;Ziegler et al, 1999;Kinde et al, 2003;Mutinelli et al, 2003;Nili & Asasi, 2003;Swayne & Pantin-Jackwood, 2006). The pattern of signs varies with the flock.…”

“…Increased mortality, decreased feed consumption, and decreased egg laying as indicators of an LPAI outbreak Although these parameters do not usually change as dramatically as they do in HPAI-infected flocks, increased mortality, decreased egg production, and decreased feed and water consumption are common in LPAI virus-infected flocks (Johnson & Maxfield, 1976;Alexander & Stuart, 1982;Bean et al, 1985;Hooper & Selleck, 1998;Ziegler et al, 1999;Kinde et al, 2003;Nili & Asasi, 2003;Mutinelli et al, 2003;Bowes et al, 2004;Swayne & Pantin-Jackwood, 2006). The baseline mortality in a chicken flock varies with the timing within the production period (Elbers et al, 2004a).…”

Water-Borne Transmission of Influenza A Viruses?

“…All of the major hemagglutinin and neuraminidase subtypes of human strains were represented among these duck isolates: Hswl, which is related to the HO ,HI, and Hswl subtypes [5]; H2, which is antigenically indistinguishable from the human H2 [3]; Hav7, which is related to H3 [2]; and both N 1 and N2, which correspond to the neuraminidase subtypes of human strains. In addition, antigenic counterparts of these duck viruses (HavlNav2 [7], Hav7NavI [8], Hav4Neq2 [9], and Hav8Nav4 [10]) have been associated with disease outbreaks in domestic avian species in North America.…”