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United States Department of Agriculture

Agricultural Research Service

Title: Prevalence of Streptococcus Iniae in Tilapia, Hybrid Striped Bass and Channel Catfish from Fish Farms in the United States

Authors
item Shoemaker, Craig
item Klesius, Phillip
item Evans, Joyce

Submitted to: Aquaculture
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2000
Publication Date: January 21, 2001
Citation: SHOEMAKER, C.A., KLESIUS, P.H., EVANS, J.J. PREVALENCE OF STREPTOCOCCUS INIAE IN TILAPIA, HYBRID STRIPED BASS AND CHANNEL CATFISH FROM FISH FARMS IN THE UNITED STATES. AQUACULTURE. 2001.

Technical Abstract: In 1995-1996, much attention was focused on Streptococcus iniae in North America because of the reported potential for human infection due to puncture wounds received while preparing tilapia for cooking. Because of the perceived risk by the public, a prevalence study was conducted to determine the prevalence of S. iniae in tilapia (Oreochromis spp.), hybrid striped bass (Morone chrysops X M. saxatilis) and channel catfish (Ictalurus punctatus) from farms in the United States. A total of 1543 fish were sampled from commercial aquaculture farms in the United States. This included 970 tilapia, 415 hybrid striped bass 158 channel catfish. The dry-swab technique for sampling of streptococcal specimens was employed to obtain samples. Samples were then shipped overnight and processed by standard bacteriological techniques for identification. Streptococcus iniae was not isolated from market size channel catfish. Prevalence in tilapia and hybrid striped bass was 3.82 and 7.23%, respectively. Prevalence by farm ranged from 0.0-27.4% for tilapia and 0.0-21.6% for hybrid striped bass. In tilapia, prevalence was lowest in market size and nursery fish (1.67 and 0.88%, respectively) with an increase in prevalence for the grow out group (7.96%). For hybrid striped bass, the prevalence was lowest in nursery (3.12) and market size fish (2.12%) and highest in grow out fish (9.56%). Prevalence in market sized tilapia and hybrid striped bass was 1.75% and was found to be 18 to 50 fold lower than fish sampled in Canada in tilapia from suppliers or retail outlets. Results of the present study do not support the contention that S. iniae is a serious public health threat associated with cultured fish, but rather a limited risk in older and immuno-compromised individuals who suffer puncturewounds while preparing fish.

Last Modified: 4/25/2014
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