Symptoms of SPD begin about one week after eating the salmon and include vomiting, diarrhea, loss of appetite, depression, high fever, and enlarged lymph nodes. Untreated, mortality reaches 90 percent. Death occurs seven to ten days after symptoms begin.
Diagnosis is through finding the fluke eggs microscopically in a stool sample. A needle aspiration biopsy of an enlarged lymph node will reveal rickettsial organisms within macrophages in many cases. The rickettsial infection can be successfully treated with antibiotics such as tetracycline, and the fluke infection can be treated with fenbendazole.
EFF has less severe symptoms than SPD, with less gastrointestinal signs and more lymph node involvement. The mortality in untreated cases is about ten percent.
A similar disease has been identified in Brazil.