Caligus rogercresseyi: possible vector in the horizontal transmission of the virus of infectious salmon anaemia (ISAv)

In 2007 Chile became the second largest producer of salmonids worldwide. The following year the salmon industry began to experience a severe health crisis produced in Chile by the virus causing infectious salmon anaemia. This virus was first recorded in Norway (1984), then in Canada, Scotland, Faroe Islands, United States and Chile in 2007. The infectious salmon anaemia (ISA) is a highly contagious disease of fish produced by a virus from the Orthomyxoviridae family. The most vulnerable species to this virus is the Atlantic salmon (Salmo salar). The parasitic plague caused by the ectoparasite copepod sea louse, Caligus rogercresseyi, has been increasing and promotes the transmission of bacterial and viral illnesses. From all the species farmed in Chile, the Atlantic salmon is the one most susceptible to infestation by C. rogercresseyi. In 2006, the industry showed a significant increase in infestation rates by Caligus, and then in 2007 appeared outbreaks of infectious salmon anaemia (ISA). In Norway, it has been shown that sea louse, Lepeophtherius salmonis, may have a role as a vector in the transmission of ISA virus, so the aim of this study was to determine whether C. rogercresseyi is a vector of transmission of infectious salmon anaemia virus in the Atlantic salmon, farmed in the south of Chile.