Fish as reservoirs and vectors of Vibrio cholerae

• Published in: PloS one Vol. 5; no. 1; p. e8607
• Main Authors: Senderovich, Yigal, Izhaki, Ido, Halpern, Malka
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06.01.2010; Public Library of Science (PLoS)
• Subjects: Animals; Aquatic birds; Aquatic environment; Aquatic habitats; Bacteria; Biology; Chitin; Cholera; Cholera toxin; Continents; Copepoda; Copepods; Digestive tract; Disease Vectors; Distributing; Ecology; Etiology; Fish; Fish ponds; Fishes; Fishes - microbiology; Freshwater environments; Freshwater fish; Freshwater lakes; Gastrointestinal tract; Gastrointestinal Tract - microbiology; Genes; Genes, Bacterial; Habitats; Health aspects; Health risks; Hospitalization; Infections; Infectious Diseases; Infectious Diseases/Bacterial Infections; Infectious Diseases/Epidemiology and Control of Infectious Diseases; Intestine; Lakes; Microbiology/Environmental Microbiology; Mugil cephalus; Pathogens; Ponds; Public health; Public Health and Epidemiology/Infectious Diseases; Reservoirs; Rivers; Sarotherodon galilaeus; Science education; Species; Species Specificity; Vibrio cholerae; Vibrio cholerae - genetics; Vibrio cholerae - isolation & purification; Water-borne diseases; Waterborne diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0008607

Vibrio cholerae, the etiologic agent of cholera, is autochthonous to various aquatic environments, but despite intensive efforts its ecology remains an enigma. Recently, it was suggested that copepods and chironomids, both considered as natural reservoirs of V. cholerae, are dispersed by migratory waterbirds, thus possibly distributing the bacteria between water bodies within and between continents. Although fish have been implicated in the scientific literature with cholera cases, as far as we know, no study actually surveyed the presence of the bacteria in the fish. Here we show for the first time that fish of various species and habitats contain V. cholerae in their digestive tract. Fish (n = 110) were randomly sampled from freshwater and marine habitats in Israel. Ten different fish species sampled from freshwater habitats (lake, rivers and fish ponds), and one marine species, were found to carry V. cholerae. The fish intestine of Sarotherodon galilaeus harboured ca. 5 x 10(3)V. cholerae cfu per 1 gr intestine content-high rates compared with known V. cholerae cfu numbers in the bacteria's natural reservoirs. Our results, combined with evidence from the literature, suggest that fish are reservoirs of V. cholerae. As fish carrying the bacteria swim from one location to another (some fish species move from rivers to lakes or sea and vice versa), they serve as vectors on a small scale. Nevertheless, fish are consumed by waterbirds, which disseminate the bacteria on a global scale. Moreover, V. cholerae isolates had the ability to degrade chitin, indicating a commensal relationship between V. cholerae and fish. Better understanding of V. cholerae ecology can help reduce the times that human beings come into contact with this pathogen and thus minimize the health risk this poses.