Farmageddon

Calbuco, southern Chile. The disease was later described as affecting Atlantic salmon Salmo salar, rainbow trout Oncorhynchus mykiss, and Chinook salmon Oncorhynchus tshawytscha.

In Chile, the losses were extensive and, on certain farms, mortalities of up to 90% were reported.‖ A scientific paper published in 1999 in the journal Diseases of Aquatic Organisms reported that: ―Piscirickettsia salmonis was first recognized as the cause of mortality among penreared coho salmon Oncorhynchus kisutch in Chile. Since the initial isolation of this intracellular Gram-negative bacterium in 1989, similar organisms have been described from several areas of the world, but the associated outbreaks were not reported to be as serious as those that occurred in Chile.‖ An article – ―Salmonid Rickettsial Septicaemia‖ – by Intervet published in 2006 stated that: ―SRS (a.k.a. Salmon Rickettsial Syndrome or Piscirickettsiosis or Coho salmon septicaemia or Huito disease) is considered to be the most important disease problem in the Chilean salmon farming industry, with economic losses of over US$100 million in some years. SRS was first reported, from Chile, in 1989, but (Pisci)rickettsia-like organisms (RLO) are now frequently associated with disease syndromes in both salmonid and non-salmonid fish from both fresh and saltwater worldwide. During 1989, this disease was considered to be the cause of death of an estimated 1.5 million Coho salmon, many near market-size. A year later, the disease was also found to occur in Atlantic salmon and up to 90% mortality was seen on some farms. Outbreaks of SRS in other countries have not reached the levels of the Chilean outbreaks. For example, variable and inconsistent mortality of 0.6 - 15% has been reported in Canada and Norway.‖ A report by the European Union in 2007 stated that: ―The clinical signs and gross lesions reported for piscirickettsiosis from natural and experimentally infected fish from Chile include anorexia, darkening of the skin, lethargy, swimming near the water surface and respiratory distress (Branson and Nieto Diaz Muñoz 1991; Cvitanich et al. 1991). Skin lesions include perianal and periocular haemorrhage, abdominal petechiae and shallow haemorrhagic ulcers, varying between 0.5 and 1.5 cm in diameter. Characteristic ring-shaped, yellow / cream-coloured subcapsular nodules can be observed throughout the liver of chronically infected fish (Cvitanich et al. 1991). The abdomen is frequently distended; splenomegaly is common with white spots occurring in the skin. Petechiae on the serosa surfaces of the intestine, pyloric caeca and swim bladder have been observed in Atlantic salmon. In other organs macroscopic changes include ascites, diffuse swelling, general pallor and multifocal pale areas in the kidney and spleen. Additionally, bilateral exophthalmia and an ulcerative inflammatory reaction around the mouth have been described. In Canada and Ireland a similar gross pathology is reported from rickettsia-like organisms among farmed Atlantic salmon (Brocklebank et al. 1992; Rodger and Drinan 1993).‖ In Australia, ‗Tasmanian richettsial disease‘ (Rickettsial-like organism specific to Tasmania) was reported in 2006. The Government reported: ―Significant and widespread disease event occurred during summer of 2006 in south-eastern Tasmania resulting in significant mortalities. Affected companies treated large volumes of stock using OTC.‖ Listeria monocytogenes (Listeriosis)