An indirect fluorescent antibody test (IFAT) was developed for detection of the rickettsia that was causing epizootics among salmonids cultured in seawater net-pens in southern Chile. Antiserum against the rickettsial agent was produced in New Zealand white rabbits with a preparation grown in antibiotic-free chinook salmon embryo (CHSE-214) cell cultures and partially purified by a combination of filtration and centrifugation steps. The IFAT was effectively used on blood films, tissue sections, and smears. Two gram-negative and two gram-positive bacterial pathogens of salmonids did not react in this test. Detection of the rickettsial agent has previously been restricted to examination by light microscopy or isolation in salmonid cells. The IFAT provides a simple, rapid, sensitive method for detection of the agent and diagnosis of the disease. The rickettsia is thought to be a member of the tribe Ehrlichieae and was tested by IFAT with sera from animals infected with other rickettsial agents.Keywords: Fish diseases, Indirect fluorescent antibody test, Salmonids, Rickettsia, ChileKeywords: Fish diseases, Indirect fluorescent antibody test, Salmonids, Rickettsia, Chil
