Abstract

Infectious salmon anaemia in the United States of America: Follow-up report No. 2 (2004)

O.I.E.
WAHIS - WOAH Disease Information (on-line)
17
27
2004
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 [27], 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 … ; destroyed: slaughtered: 4,000

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.

Epidemiology:
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


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