Another occurrence of IPN in juvenile rainbow trout in inland waters


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In July, the IPN disease (infectious pancreatic necrosis) was detected in two inland water fish farms located in the river basins of Kymijoki and Vuoksi. The disease was last found in inland waters in March 2012 in the Kymijoki river basin. The virus causing the IPN disease is discovered in the Finnish sea area every year, but in the past, it has been very rare in inland waters. The IPN virus is harmless to people and does not prevent the consumption of affected fish.

Typical symptoms of IPN were detected in rainbow trout in one of the two fish farms that have now tested positive for the disease. In the other farm, samples were taken as part of routine testing. It is possible that the virus causing the IPN disease transferred from one of the two fish farms to the other through fish or equipment prior to the detection of the disease. Further investigations and measures to prevent the spread of IPN within inland waters have begun.

Juvenile fish affected
The IPN disease affects salmonids, mainly the rainbow trout, the brown trout, the powan, the salmon and the brook trout. It is caused by the birnavirus, which persists well in a wide variety of conditions. Typical IPN symptoms include high mortality in juvenile fish, particularly among the fastest-growing individuals, darkening of the skin, haemorrhages in the visceral organs, bulging eyes and stomach and "spiral swimming". If these symptoms occur on a fish farm, they must be immediately reported to an official veterinarian.

The disease is most frequently found in juvenile salmonids when waters are cool. The key source of infection is infected fish carrying the disease. IPN may spread from one fish to another through water, from spawners to eggs and through fish farming equipment. Disinfecting eggs may not necessarily kill the virus. As there is no treatment for the disease, it can only be eliminated by emptying and disinfecting the fish farm.

IPN is an animal disease which requires control
IPN is an animal disease which requires legislative control in inland water areas. Any measures taken to eradicate the disease are led by the authorities. The Finnish inland water area has IPN-free status, granted by the EU. Health-certified inland spawning farms and hatcheries are tested for IPN by the state, at least every second year. After the detection of an infection, the infected fish farm is given restrictive orders, preventing the transfer of fish to and from the farm.

Read more about IPN (in Finnish):
Etusivu > Eläimet > Eläinten terveys ja eläintaudit > Eläintaudit > Kalat ja ravut > IPN

For more information, contact:
Senior Inspector Tiina Korkea-aho (fish disease control), tel. +358 40 351 3318,
Researcher Satu Viljamaa-Dirks (fish disease research), tel. +358 44 720 1469,
Senior Researcher Tuija Gadd (fish viral diagnostics) tel. +358 50 357 0328,

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