Fish as Reservoirs and Vectors of Vibrio cholerae

Abstract

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. 5×103 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.

Vibrio cholerae non-O1/non-O139 infection in fish in the Czech Republic

“…The common nase, which was the most severely affected species, is not a typical benthophage, but its pathological relevance is linked to the fact that while scraping algae off hard surfaces it also eats, besides the biofilm, the organisms present in the benthic fauna. This feeding habit is not uncommon in the nase, as observed on many occasions at other sites and the hypothesis is in keeping with the findings of Senderovich et al (2010) and Halpern et al (2008), referred to above. They suggested that fish serve as an intermediate vector of V. cholerae since they create a link in the food chain between chironomids and copepods on the one hand and water birds on the other.…”

“…Du Preez et al (2010) conducted a study to determine whether the estuarine and freshwater environment in Beira, Mozambique, serves as a reservoir of Vibrio cholerae O1 and doi: 10.17221/7921-VETMED O139. Senderovich et al (2010) found that fish of various species and habitats contain V. cholerae non-O1/ non-O139 in their digestive tract. They suggested that fish serve as intermediate vectors of V. cholerae since they create a link in the food chain between chironomidae and copepods on the one hand and waterbirds on the other (Halpern et al 2008).…”

Occurrence of Vibrio cholerae in fish and water from a reservoir and a neighboring channel in Ouagadougou, Burkina Faso

“…Cholera vibrios are commonly transmitted to humans through ingestion of contaminated food or water, and the disease occurs mainly in developing countries with inadequate sanitation [5][6][7]. Studies have suggested that fish may act as reservoirs and vectors of V. cholerae [8]. While an estuarine environment represents an ideal setting for the survival and persistence of V. cholerae, cholera has also become endemic in arid and inland areas of Africa [9] such as Burkina Faso [10].…”

Non-Selectivity of R-S Media for Aeromonas hydrophila and TCBS Media for Vibrio Species Isolated from Diseased Oreochromis niloticus

“…Vibrio alginolyticus and Vibrio cholerae are major pathogens in Chinese aquatic products [15]. Senderovich et al [42] isolated Vibrio cholera from Oreochromis aureus; Rehulka et al [43] isolated pathogenic Vibrio cholerae non-O1/non-O139 from moribund freshwater fish, and proved its ability to induce disease condition through experimental infection of common carp, infected carb developed typical signs of Vibriosis. Unidentified pathogenic bacteria represent 3.3% (one out of 30 isolates).…”