Infection of Tilapia Oreochromis sp. by Vibrio vulnificus in Freshwater and Low‐salinity Environments

Abstract

The first isolation of Vibrio vulnificus in southern Taiwan from hybrid tilapia Oreochromis sp. raised in freshwater and brackish water environments is documented in this report. The infection was only found in fish in ponds where the salinity was less than 10 ppt. Tilapia raised in water of higher salinities in the same region were not affected. Grossly visible signs of infection included dark coloration, lethargy, and external hemorrhage and ulceration of the skin. The most prominent internal signs of infection included splenomegaly and severe hemorrhagic lesions in the liver. Septicemia was documented in moribund fish. All bacterial isolates from moribund fish were tested by polymerase chain reaction, using V. vulnificus hemolysin/cytolysin gene‐specific primers. Sequence data from the 16S ribosomal RNA gene suggest that these isolates were V. vulnificus. The isolates were indole and mannitol positive, characteristics shared by human clinical isolates and isolates from freshwater European eel, Anguilla anguilla. The isolates from tilapia were unique in that they were negative for ornithine decarboxylase and citrate.

The Fish Pathogen Vibrio vulnificus Biotype 2: Epidemiology, Phylogeny, and Virulence Factors Involved in Warm-Water Vibriosis

“…Afterwards, the disease was reported in different European eel farms, including those from Nordic countries (notably Germany, Holland, and Denmark) (30, 31; and personal communications with different eel farmers). In parallel, new warm-water vibriosis cases, which affected other farmed fish species and shrimps were reported worldwide (21,22,23,24). None of these cases caused the detrimental effects that warm-water vibriosis produced on eel aquaculture (personal communications with different eel farmers).…”

“…The most susceptible host for this vibriosis is the eel (Anguilla anguilla and A. japonica) (20). Other susceptible hosts are derbio (Trachinotus ovatus) (21), tilapia (Oreochromis sp) (22), trout (Oncorhynchus mykiss) (23), and shrimp (Penaeus vannamei) (24). Warm-water vibriosis in its acute form is also a primary septicemia, but in this case, it is triggered irrespectively of the pathogen's route of entry (gills, intestine, skin injury) and/or the host's immune status (25).…”

Serotype distribution and antimicrobial susceptibilities of Streptococcus agalactiae isolated from infected cultured tilapia (Oreochromis niloticus) in Thailand: Nine-year perspective

“…The major pathogenic bacteria responsible for mortalities in tilapia include Aeromonas hydrophila (Tipmongkolsilp et al, 2012), Francisella noatunensis subsp. orientalis (Soto et al, 2013), Flavobacterium columnare (Dong et al, 2015), Vibrio vulnificus (Chen et al, 2006), Streptococcus iniae (Suanyuk et al, 2010) and Streptococcus agalactiae (group B Streptococcus, GBS) (Suanyuk et al, 2008).…”

Vibrio vulnificus outbreaks in Dutch eel farms since 1996: strain diversity and impact

“…Additionally, V. vulnificus has been isolated from disea sed fish from brackish and marine waters, mainly from severely diseased eels (Kusuda et al 1979, Biosca et al 1991, Høi et al 1998, Fouz et al 2006, Esteve & Alcaide 2009), but also from diseased tilapia Oreochromis niloticus (Sa kata & Hattori 1988, Bisharat et al 1999, Fouz et al 2002, Chen et al 2006, carp Cyprinus carpio (Bis harat et al 1999, Mouzopoulos et al 2008 and from various sea fish species (DePaola et al 1994, Mouzopoulos et al 2008, Rajapandiyan et al 2009). In humans, V. vulnificus can be a zoonotic invasive pathogen (Austin 2010).…”