Analysis of risk factors for isolated outbreak of infectious salmon anaemia (ISA) in marine farms with Atlantic salmon
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1
Norwegian Veterinary Institute, Norway
Since, 1993, there has been between one and 20 annual outbreaks of infectious salmon anaemia (ISA) in Norway. The outbreak pattern is characterized by isolated outbreaks (unknown source of infection) and local epidemics (infection from close neighbor with ISA).
The occurrence of an isolated ISA outbreak may be caused by a low virulent variant of ISA virus (ISAV HPR0) mutating into virulent ISA virus. Knowledge on ISAV-HPR0 is scarce. Understanding of the possible mechanisms and triggers of a transition from ISAV-HPR0 into virulent ISAV is needed in order to prevent and reduce the occurrence of isolated ISA outbreaks in the future. Here, we use data from isolated ISA outbreaks in marine farms with Atlantic salmon between 2003 and 2015 to identify the associated risk factors. Isolated ISA outbreaks were identified with a model described in Aldrin et al. (2011), and we use generalized linear models to test numerous possible risk factors; including local biomass density, mortality, sea temperature, distance to the slaughterhouse, the occurrence of other diseases, moving, lice treatment etc. The results from this analysis will be presented.
References
Aldrin M, Lyngstad TM, Kristoffersen AB, Storvik B, Borgan Ø, Jansen PA (2011). Modelling the spread of infectious salmon farms based on seaway distances between ISA virus isolates. Journal of the Royal Society Interface 00; 1-11.
Keywords:
Infectious salmon anaemia,
Atlantic salmon,
Risk factors,
ISAV-HPR0,
isolated ISA outbreak
Conference:
AquaEpi I - 2016, Oslo, Norway, 20 Sep - 22 Sep, 2016.
Presentation Type:
Oral
Topic:
Aquatic Animal Epidemiology
Citation:
Lyngstad
TM,
Qviller
L,
Sindre
H and
Kristoffersen
AB
(2016). Analysis of risk factors for isolated outbreak of infectious salmon anaemia (ISA) in marine farms with Atlantic salmon.
Front. Vet. Sci.
Conference Abstract:
AquaEpi I - 2016.
doi: 10.3389/conf.FVETS.2016.02.00035
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Received:
30 May 2016;
Published Online:
14 Sep 2016.
*
Correspondence:
Dr. Trude M Lyngstad, Norwegian Veterinary Institute, Oslo, Norway, trude.lyngstad@vetinst.no