Piscirickettsia salmonis, “Piscirickettsiosis”

Salmon cells in tissue culture that have been infected with P. salmonis; the dark clusters are dying, infected cells. Image courtesy of WADDL Microbiologists Jo-Lynn Reno and Katie McMenamin-Snekvik.

What is it?

Piscirickettsia salmonis is a bacterium that causes piscirickettsiosis. This disease can cause high mortality in salmon that live in a marine environment. It is a pathogen of concern for many international fish health regulatory authorities, and it is common to test fish for this bacterium as part of export certification testing.

P. salmonis is a unique bacterium because it invades and replicates inside of the host fish’s cells. Unlike most other bacteria, which are cultured in the laboratory on agar plates, P. salmonis must be grown in tissue culture (see image below). This makes it different and sometimes more difficult to test for than most fish bacterial pathogens.

Testing Methods

Certification Testing: WADDL offers screening via PCR for P. salmonis

P. salmonis in tissue culture. Image provided by Dr. Kevin Snekvik.

Diagnostic Testing: Necropsy in conjunction with histopathology and PCR are the most common tests used to diagnose piscirickettsiosis in fish. See the “Aquatic Species: Diagnostic Testing” resource for information about how to select and submit appropriate samples for diagnostic testing at WADDL.

How can I get more information about certification and diagnostic testing for Piscirickettsia salmonis?

For more information about submitting fish for P. salmonis testing at WADDL, please contact us.