Salmonella infections in white ibis nestlings in urban areas as a result of environmental contamination reveal a potential health risk to humans and animals.

Abstract

Salmonella is an important zoonotic pathogen of wildlife and humans. Adult white ibis (Eudocimus albus), an abundant bird in urbanized landscapes in Florida, have a high Salmonella prevalence (26%). Salmonella surveillance of nestlings improves our understanding of transmission and infection dynamics and disease risks. To determine Salmonella epidemiology in ibis nestlings, 2 studies were conducted. First, 24 free-living ibis chicks were captured for an experimental infection trial to evaluate susceptibility and clinical outcome. Most (58%) were shedding Salmonella at capture, but prevalence decreased to zero. After there were no Salmonella detections for 5 weeks, the chicks were inoculated with 106 Salmonella Typhimurium. Seven had evidence of inoculation: 3 of 7 (42.8%) shed at 1 day following inoculation and 1 of 7 (14.2%) at 5 days following inoculation. Only 1 bird developed clinical signs for approximately 24 hours. Second, the Salmonella prevalence between free-living nestlings from 1 urban and 2 natural rookeries were compared. Weekly sampling from hatch until fledging revealed Salmonella shedding up to 22 days. Salmonella prevalence was higher in the urban nestlings. Thirty-two serotypes were detected; Salmonella Rubislaw and Salmonella Reading were the most common, and 19% and 13% of serotypes were in the top 10 and 20 responsible for human cases in the US, respectively. These studies show an absence of clinical disease with Salmonella infection in young birds and the demographic and anthropogenic factors that impact Salmonella shedding, relevant at the human-wildlife interface. An important aspect of Salmonella epidemiology is environmental persistence, which is addressed in a companion Currents in One Health by Perez et al, AJVR, June 2025.