Lactococcus garvieae and Streptococcus iniae infections in rainbow trout Oncorhynchus mykiss:similar, but different diseases

Abstract

ABSTRACT. Chnical and macroscopic findings (anorexia, lethargy, loss of orientation and exophthalmia) indicate that Streptococcus ~n i a e and Lactococcus garvieae infections of trout share some common features, but histopathology reveals notable differences between the 2 diseases. Meningitis and panophthalmitis are the main lesions among S. iniae infected trout, whereas L. garvieae infection results in a hyperacute systemic disease. Differences in the LD,,s of the 2 pathogens and the sudden onset of signs and death correlate with the histopathological findings, indicating the severity of L. garvieae infection of trout.KEY WORDS Trout . Streptococcus iniae . Lactococcus garvieae Pathology . Experimental disease During the last decade, Gram-positive cocci have become important fish pathogens. Epidemic and sporadic diseases have been reported from different parts of the world, notably Japan

Development of a sensitive and specific LAMP PCR assay for detection of fish pathogen Lactococcus garvieae

“…However, similar clinical signs are also found in Streptococcus sp. infections (Eldar & Ghittino 1999).…”

“…However, similar clinical signs are also found in Streptococcus sp. infections (Eldar & Ghittino 1999).Molecular detection methods of Lactococcus garvieae have been developed, including polymerase chain reaction (PCR) (Zlotkin et al 1998, Aoki et al 2000, Pu et al 2002 and 16S rRNA and sodA sequence analysis (Fihman et al 2006). However, although considered rapid and specific methods for detection, these require expensive equipment and other costly materials (Gunimaladevi et al 2005).…”

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“…Also, it has been reported in a number of species of fish, such as barramundi (Lates calcarifer) (Creeper and Buller, 2006), Nile tilapia (Oreochromis niloticus) (Shoemaker et al 2001) and rainbow trout (Oncorynchus mykiss) (Lahav et al, 2004) as well as in mammals (Pier andMadin, 1976 andFacklam et al, 2005). In rainbow trout, streptococcosis is characterized by a subacute to acute course, with specific lesions of panophthalmitis and meningitis beside minor pathological changes in other organs (Eldar and Ghittino, 1999). Moreover, S. iniae has recently emerged as a threat to public health due to its zoonotic importance, being isolated from humans infected due to accidental injuries during handling of fresh infected fish (Weinstein et al, 1997;Lau et al, 2003;Koh et al, 2004;Facklam et al, 2005;Lau et al, 2006 andSun et al, 2007).…”

Molecular characterization and virulence gene profiling of pathogenicStreptococcus agalactiaepopulations from tilapia (Oreochromissp.) farms in Thailand

“…25 To date, streptococcosis, which has been recognized as a significant cause of massive fish mortality, has spread to many continents and has resulted in enormous economic loss in the global aquaculture industries (Yanong RPE, et al: 2010, Streptococcal infections of fish). Several species of sea and freshwater fish have been reported to be susceptible to Streptococcus agalactiae (group B streptococci [GBS]) infection, including rainbow trout (Oncorhynchus mykiss), 8 hybrid striped seabass (Morone saxatilis × M. chrysops), 29 channel catfish (Ictalurus punctatus), 29 wild mullet (Klunzinger's mullet; Liza klunzingeri), 10 and Nile tilapia (Oreochromis niloticus). 32 Seventy percent accumulated mortality can occur due to chronic infection over several weeks (Yanong RPE, et al: 2010), and in some cases, more than 50% mortality within 3 -4 days has been reported in severely acute infections (Yanong RPE, et al: 2010, Streptococcal infections of fish).…”