Date: Tue, 12 Oct 1999
From: Erin Bromage erin.bromage@jcu.edu.au

Streptococcus Iniae, Fish


There have been quite a few outbreaks of _Streptococcus iniae_ in saltwater and brackish environments worldwide, including Australia, China, Thailand, and Japan, most of which have been associated with aquaculture.

Here in Northern Australia, S.iniae has emerged as a serious pathogen of Lates calcarifer (barramundi), grown in sea cages. Recently, however, there have been 2 large epizootics in wild fish, with fish losses estimated at about 5-10 tons.

I have found that many species of fish are carriers, or are susceptible to S. iniae, including fish found on the Great Barrier Reef (especially the siganids (rabbit fish) and puffers), most of which die quite rapidly (12-48hrs) after initial exposure to the pathogen.

In my experience S. iniae is highly infective in freshwater, and only just slightly less so in saltwater (comparison done on Euryhaline fish species).

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Erin Bromage
Aquatic Microbiology and Pathobiology
Department of Microbiology and Immunology
James Cook University, Townsville, 4811 Australia

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