Avian Influenza Virus Status and Maternal Antibodies in Nestling White Ibis (Eudocimus albus)

Abstract

The White Ibis (Eudocimus albus), a nomadic wading bird, has increased its exploitation of urban habitats in South Florida, United States, and has recently established several urban breeding colonies. Certain characteristics of ibis ecology could position them in the natural cycle of the avian influenza virus (AIV). In fact, experimentally infected ibises were shown to be competent hosts for multiple AIV subtypes, and seroconversion to AIV has been documented in adult ibises in natural populations. However, the mechanisms of transmission and the timing of infection are unclear as we have yet to isolate AIV from a free-living ibis. To investigate the age-specific AIV dynamics of ibis, we captured nestlings (n = 115) weekly for 1–4 weeks from urban and natural settings in 2020 and 2021. We collected choanal/cloacal swabs for rRT-PCR and virus isolation, and plasma to screen for maternal AIV antibodies. AIV was not detected in any individual by virus isolation; however, maternal antibodies to AIV were detected in 95% of nestlings, with varying rates of catabolism. These results confirm that nestlings are afforded maternal antibodies from adults at rates reflective of higher adult seroprevalence than previously documented and that nestlings in breeding colonies may have some degree of protection and are unlikely to become infected with AIV.

Effect of 2020–21 and 2021–22 Highly Pathogenic Avian Influenza H5 Epidemics on Wild Birds, the Netherlands

“…Unattended chicks from dead parents most likely died because of lack of parental care. Maternal antibodies have been described in chicks of previously infected parents, but clinical protection is short-lived and requires high maternal antibody titers (27,28). Furthermore, maternal antibodies are only relevant if the infection has occurred before egg laying.…”

White‐faced and Black‐faced ibises foraging on predictable anthropogenic food subsidies in Patagonia, Argentina

“…Other ibis species associated with urbanized and agricultural landscapes were shown to transport Salmonella enterica , Newcastle disease virus, avian influenza virus or flaviviruses from livestock areas (Christie et al, 2021; Epstein et al, 2006; Hernandez et al, 2016). Black‐faced and White‐faced ibises foraging at anthropogenic food sources along the lower Chubut River Valley may be a matter of sanitary concern, as they could act as carriers of pathogens to freshwater areas where other species congregate to rest and/or forage.…”

An Acute Mortality Event Associated with Novel Macrorhabdus ornithogaster Infection and Underlying Factors in a Newly-Established Captive Group of American White Ibis (Eudocimus albus) Nestlings

“…Our work with Salmonella spp. in free-living nestlings demonstrates that shedding birds, even nestlings, do not exhibit clinical disease (Christie 2021). Although we did not observe gross or histopathologic lesions consistent with hypervitaminosis E, liver vitamin E levels in the birds that died were higher (252–455 µg/g dry weight liver, Michigan State University Veterinary Diagnostic Laboratory (MSU VDL, Lansing, Michigan, USA) than those reported in chickens (45–120 µg/g, MSU VDL) and similar to liver levels of pink-backed pelicans ( Pelecanus rufescens ) that died of acute vitamin E toxicosis (244–500 µg/g; Nichols et al 1989; Sünder et al 1999).…”