Clifford E. Starliper
2005
<p><span>Furunculosis, caused by the bacterium </span><i><span class="genus-species">Aeromonas salmonicida</span></i><span>, was artificially induced in brook trout (</span><i><span class="genus-species">Salvelinus fontinalis</span></i><span>) in an experimental tank. Ebonyshells (</span><i><span class="genus-species">Fusconaia ebena</span></i><span>) were placed to cohabit with these fish to acquire the pathogen through siphoning. After 2 wk of cohabitation, 10 of the mussels were assayed by bacterial culture and all were found to harbor </span><span class="genus-species">A. salmonicida</span><span>. The mean cell count from soft tissue homogenates was 1.84 × 10</span><sup>5</sup><span> cfu/g, which comprised an average 14.41% of the total bacteria isolated from tissues. From the fluids, a mean of 2.84 × 10</span><sup>5</sup><span> </span><i><span class="genus-species">A. salmonicida</span></i><span> cfu/mL was isolated, which comprised an average of 17.29% of the total bacterial flora. The mussels were removed from the cohabitation tank and distributed equally among five previously disinfected tanks, 35 per tank. The </span><i><span class="genus-species">F. ebena</span></i><span> in each tank were allowed to depurate </span><i><span class="genus-species">A. salmonicida</span></i><span> for various durations: 1, 5, 10, 15 or 30 days. After each group had depurated for their assigned time, 10 were assayed for bacteria, tank water was tested, and 20 pathogen-free bioindicator brook trout were added to cohabit with the remaining mussels. Depuration was considered successful if </span><i><span class="genus-species">A. salmonicida</span></i><span> was not isolated from tank water or the mussels, and there was no infection or mortality to bioindicator fish. After 1 day of depuration, </span><i><span class="genus-species">A. salmonicida</span></i><span> was not isolated from the soft tissues; however, it was isolated from one of the paired fluids (10% prevalence). The tank water tested positive, and the bioindicator fish became infected and died. From the 5-day depuration group, </span><i><span class="genus-species">A. salmonicida</span></i><span> was not isolated from soft tissues, but was isolated from three fluids (30%; mean = 1.56 × 10</span><sup>2</sup><span> cfu/mL). Tank water from the 5-day group was negative, and there was no mortality among the bioindicator fish. However, </span><i><span class="genus-species">A. salmonicida</span></i><span> was isolated from 2 of 20 fish at the end of the 14-day observation period. One </span><i><span class="genus-species">F. ebena</span></i><span> fluid sample was positive for </span><i><span class="genus-species">A. salmonicida</span></i><span> from the 10-day depuration group, but none of the soft tissue homogenates. The pathogen was not isolated from 10-day tank water, but there was a 30% cumulative mortality to the bioindicator fish. </span><i><span class="genus-species">Aeromonas salmonicida</span></i><span> was not isolated from any of the soft tissue homogenates, fluids or tank water from the 15 day or 30 day depuration groups, and the bioindicator fish remained pathogen- and disease-free. Study results showed that the </span><i><span class="genus-species">F. ebena</span></i><span> were harboring a high </span><i><span class="genus-species">A. salmonicida</span></i><span> cell load going into depuration, but at 15 days and beyond, the pathogen had been depurated to the extent that the mussels did not serve as pathogen vectors.</span></p>
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10.2983/0730-8000(2005)24[573:QOASEM]2.0.CO;2
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National Shellfisheries Association
Quarantine of Aeromonas salmonicida-harboring ebonyshell mussels (Fusconaia ebena) prevents transmission of the pathogen to brook trout (Salvelinus fontinalis)
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