Prevalence of Streptococcus iniae in tilapia, hybrid striped bass, and channel catfish on commercial fish farms in the United States.
OBJECTIVE
To determine the prevalence of Streptococcus iniae in tilapia (Oreochromis spp), hybrid striped bass (Morone chrysops X M saxatilis), and channel catfish (Ictalurus punctatus) on commercial fish farms in the United States.


METHODS
1,543 fish (970 tilapia, 415 hybrid striped bass, and 158 channel catfish).


METHODS
The dry-swab technique was used for collection of specimens for streptococcal isolation. Specimens were shipped by overnight delivery and processed by use of standard bacteriologic techniques.


RESULTS
Streptococcus iniae was not isolated from market-size channel catfish. Prevalence in tilapia and hybrid striped bass was 37 of 970 (3.81%) and 30 of 415 (7.23%), respectively. Prevalence by farm ranged from 0.0 to 27.4% for tilapia and 0.0 to 21.6% for hybrid striped bass. In tilapia, prevalence was lowest in market-size and nursery fish (4 of 239 [1.67%] and 3 of 339 [0.88%], respectively), with an increase in prevalence for fish in the grow-out stage (30 of 337 [7.96%]). For hybrid striped bass, prevalence was lowest in nursery and market-size fish (3 of 96 [3.12%] and 1 of 47 [2.12%], respectively) and highest in fish in the grow-out stage (26 of 272 [9.56%]). Prevalence in market-size tilapia and hybrid striped bass was 5 of 286 (1.75%).


CONCLUSIONS
Results of this study do not support the contention that S iniae is a serious public health threat associated with commercially raised fish; rather, it represents a limited risk for older or immunocompromised people who incur puncture wounds while handling and preparing fish.
Shoemaker
C A
CA
USDA-Agricultural Research Service, Aquatic Animal Health Research Laboratory, Auburn, AL 36830, USA.
Klesius
P H
PH
Evans
J J
JJ
D000818:Animals; D001492:Bass / Q000382:microbiology; D015169:Colony Count, Microbial; D005393:Fish Diseases / Q000453:epidemiology / Q000382:microbiology*; D005398:Fisheries; D005399:Fishes / Q000382:microbiology*; D007059:Ictaluridae / Q000382:microbiology; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology / Q000662:veterinary*; D013291:Streptococcus / Q000302:isolation & purification*; D017210:Tilapia / Q000382:microbiology; D014481:United States / Q000453:epidemiology