Our study opens an exciting new direction for understanding the global spread of V. cholerae, great cormorants get infected with this bacterial species. Additionally, we have demonstrated that by consuming fish naturally infected with V. Our current results reveal that different areas of the cormorant intestine have a qualitatively unique bacterial composition, even though the microbiome of each individual differs from the microbiomes of all the others. cholerae in transferring the bacteria to the birds. Here we studied the microbiome composition of the cormorant’s intestine and the possible role of fish infected with V. As a result, the Israeli authorities allow each fish farm to shoot down up to six cormorants per fish farm per day 30. This large number of fish-eating birds causes problems for the fish industry in Israel, as has been described for other countries. The figures are between 17,000 and 29,000 individuals 30. Recently, cormorants have increased in number of individuals, thereby causing trouble for commercial and sports fisheries in lakes and rivers all over Eurasia 27, 28 and North America ( Phalacrocorax auratus) 29.Ī rise in the numbers of great cormorants arriving from Europe to over-winter in Israel from October to March has been demonstrated. They are opportunistic predators that consume a wide range of fish species of diverse size 25, 26. Great cormorants are known as generalist foragers 21 or specialist piscivores 22, with a variety of regional 23 and seasonal 24 diets. Campylobacter, Escherichia coli and Salmonella were cultured from cloacal and pharyngeal swabs of double-crested cormorant chicks in Canada 20. Buck 19 studied the presence of halophilic Vibrios and Candida albicans from different bird species in the USA and found these pathogens in the feces of one double-crested cormorant ( Phalacrocorax carbo). This finding was supported by evidence from the literature that cholera cases have been associated with eating, consumption and cleaning of different fish species in different parts of the world 14, 15, 16, 17, 18.īecause fish are commonly consumed by various waterbird species, they may also create a link between V.
Indeed, we recently demonstrated that fishes are also reservoirs of V. Furthermore, many fish species feed on copepods and chironomids 12, hence may act as a vector of cholera. Support for this hypothesis was also found in the literature 10, 11. cholerae may be dispersed by migratory waterbirds, which consume chironomids or copepods (endozoochory) or carry them externally (epizoochory) 6, 9. Considering these findings we hypothesized that V. 8 found that chironomids and copepods can be transferred across waterbodies via waterbirds. However, it is still not clear how this bacterium spreads all over the world 6. Copepods and chironomids are both considered natural reservoirs of V. The bacteria are endemic in the aquatic environments 1. Vibrio cholerae is the etiologic agent of cholera, a devastating diarrheal disease which causes epidemics and pandemics. The large-scale movements of many fish-eating birds provide a potential mechanism for the global distribution of V. Hence, we demonstrate that fish-eating birds can be infected with V. cholerae in the feces of the tilapia-fed, but not in the goldfish/koi-fed, cormorants. cholerae, and the other was fed exclusively on goldfish or on koi that were V. One group was fed exclusively on tilapias, which are naturally infected with V.
Prior to the experiment, the feces of the cormorants were V. We subsequently tested eight captive, hand-reared cormorants, divided into two equal groups. cholerae-positive wild cormorants, the presence of a gene for cholera toxin ( ctxA) was detected. cholerae in the microbiome of 5/7 wild cormorants’ intestine. Our aim was to determine if fish-eating birds act as vectors in the spread of V. cholerae is abundant in aquatic habitats and is known to be borne by copepods, chironomids and fishes. Despite its importance, the way of its global dissemination is unknown. Vibrio cholerae is the cause of cholera, a devastating epidemic and pandemic disease.
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