INFECTIOUS SALMON ANAEMIA IN THE UNITED STATES OF AMERICA
Follow-up report No. 2
See also: 4 July 2003 , 20 June 2003
Information received on 28 June 2004 from Dr Peter Fernandez, Associate Administrator, Animal and Plant Health Inspection Service, United States Department of Agriculture (USDA), Washington, DC:
End of previous report period: 3 July 2003 (see Disease Information , 16 , 161, dated 4 July 2003).
End of this report period: 28 June 2004.
New outbreak: Location: State of Maine, Cobscook Bay, Deep Cove. No. of outbreaks: 1 farm
Description of affected population: Atlantic salmon( Salmo salar ).
Total number of animals in the new outbreak: species: pis; susceptible: 7,000; cases: 1 cage; deaths
Diagnosis: samples were taken on 1 June 2004.
A. Laboratory where diagnosis was made: MicroTechnologies Inc., Richmond, Maine.
B. Diagnostic tests used:
- Positive results from the RT-PCR(1) were obtained on 4 June 2004.
- Virus isolation results were obtained on 14 June 2004 confirming the RT-PCR results.
A. Source of agent / origin of infection: unknown. This is the fourth detection of infectious salmon anaemia (ISA) in this area in Maine.
B. Mode of spread: ISA virus is considered a slow spreading low virulent virus. The mode of spread of ISA virus may be passive in seawater, may be via sea lice as a vector, or there may be a natural host acting as a reservoir, although none of these has been confirmed in the field.
Control measures during reporting period:
- the cage was voluntarily harvested on 10 June 2004 due to suspicion of ISA based on surveillance testing;
- control of arthropods (sea lice);
- quarantine and movement control inside the country.
(1) RT-PCR: reverse transcriptase - polymerase chain reaction