Migratory birds along the Mediterranean – Black Sea Flyway as carriers of zoonotic pathogens

Abstract

At the crossroad between Europe, Asia, and Africa, Bulgaria is part of the Mediterranean - Black Sea Flyway (MBSF) used by millions of migratory birds. In this study, bird species migrating through Bulgaria were investigated as carriers of zoonotic pathogens. In total, 706 birds belonging to 46 species were checked for the presence of various bacterial pathogens (Campylobacter, Yersinia, Salmonella, Listeria, Escherichia coli, Staphylococcus aureus, Francisella tularensis, Coxiella burnetii, Borrelia burgdorferi, and Brucella spp.). From 673 birds we investigated fecal samples, from the remaining 33, blood samples. We detected Campylobacter 16S rDNA gene in 1.3% of birds, but none were of pathogenic Campylobacter jejuni and Campylobacter coli species. Escherichia coli 16S rDNA gene was found in 8.8% of the birds. Out of 34 birds that transported Yersinia enterocolitica strains (5.05%), only 1 carried a pathogenic isolate. Three birds (0.4%) were carriers of nonpathogenic Salmonella strains. Four avian samples (0.6%) were positive for Listeria monocytogenes and 1 (0.15%) was positive for Brucella spp. None of the birds tested carried the tick-borne pathogens C. burnetii or B. burgdorferi sensu lato. Antibiotic-resistant strains were detected, suggesting that migratory birds could be reservoirs and spreaders of bacterial pathogens as well as antibiotic resistance genes.

Carriage and potential long distance transmission of Listeria monocytogenes by migratory black-headed gulls in Dianchi Lake, Kunming

“…The prevalence of L. monocytogenes in black-headed gull feces averaged 0.87% with 1.0%, 1.0% and 0.6% per year from 2016 to 2018, and the occurrences in environmental samples of Dianchi Lake were 0% except in 2017 with 0.7% [19]. The occurrences of L. monocytogenes in black-headed gull feces were similar to the result of a recent study of pathogen carriage by migratory birds along the Mediterranean- Black Sea Flyway at 0.6% of L. monocytogenes [28]. Of the 28 L. monocytogenes isolates obtained from black-headed gulls, 50% of the isolates were serotype 4b which is known to be responsible for the majority of listeriosis outbreaks reported [11].…”

Molecular survey on the occurrence of avian haemosporidia, Coxiella burnetii and Francisella tularensis in waterfowl from central Italy

“…Two studies have been carried out on ticks collected from birds in Italy: Toma et al (2014) detected C. burnetii DNA in 42/127 analysed ticks collected from migratory birds of different species, but not waterfowl; Pajoro et al (2018) did not detected C. burnetii and F. tularensis in any ticks collected from 124 wild birds. A recent investigation has been carried out on fecal samples collected from 673 migratory birds along the Mediterranean – Black Sea flyway and bacteriological and molecular analyses found neither F. tularensis nor C. burnetii (Najdenski et al, 2018).…”

Expanding the host range: infection of a reptilian host (Furcifer pardalis) by an atypical Brucella strain

“…The core has 647,357 amino acid residues/bp per genome, 11,005,069 in total. GenBank accession numbers are given in parentheses; bar, 0.01 nucleotide substitutions per site; isolation sources are indicated as follows: mammals (blue), reptile (red), amphibians (black), fish (green) of one molecular proof in an avian blood sample of a migratory bird, but without any clinical signs (Najdenski et al 2018;Wareth et al 2020). However, since chicken embryos are susceptible and pathologies do occur depending on infection strains, brucellosis in birds needs further evaluation (Wareth et al 2020).…”

“…This picture is far less clear in birds, where occasionally anti- Brucella antibodies have been found, but more in depth studies are lacking, especially with respect to direct detection and clinical disease due to these microorganisms (Wareth et al 2020 ). No natural Brucella infections have been described in adult birds to date with the exemption of one molecular proof in an avian blood sample of a migratory bird, but without any clinical signs (Najdenski et al 2018 ; Wareth et al 2020 ). However, since chicken embryos are susceptible and pathologies do occur depending on infection strains, brucellosis in birds needs further evaluation (Wareth et al 2020 ).…”