Introduction

• Salmon poisoning disease (SPD) is not actually a poisoning. It is a rickettsial disease transmitted by a specific trematode (helminth)Nanophyetus.
• Signs: fever, anorexia, lethargy, depression, weight loss, diarrhea.
• Diagnosis: history, clinical signs, fecal analysis, lymph node cytology.
• Treatment: symptomatic and doxycycline or tetracycline.
• Prognosis: good if treated early. SPD is highly fatal without treatment.

Pathogenesis

Etiology

• Salmon poisoning disease (SPD) is a rickettsial disease, closely related toN.(Ehrlichia) risticiiandN.(Ehrlichia) sennetsu.
• There are thought to be two primary agents causing SPD:
  • Neorickettsia helminthoeca Neorickettsia helminthoeca and
  • Elokomin fluke fever (EFF) agent.
• Some researchers feel that EFF is actually another strain ofN. helminthoeca. Other strains ofNeorickettsiamay also be involved.

Predisposing factors

• Dogs that live along water in the Pacific Northwest and are allowed to roam and ingest raw fish are at increased risk.

Pathophysiology

• The rickettsial organism is harbored in the trematode,Nanophyetus salmincola.
• This fluke requires three different hosts to complete its life cycle:
  • Snails (Oxytrema silicula), fish (salmonoid) and mammals/birds.
• The larva of the fluke carrying the rickettsial organism leave the snail and penetrate a salmonoid fish, where it can localize anywhere in the body. A dog (or other definitive host) then ingests the infected fish and the adult fluke develops in the intestine. After attaching to the intestinal mucosa, through an unknown mechanism, the fluke inoculates the dog with the rickettsia. Eggs of the fluke are passed in the feces, which hatch and infectOxytremasnails.

Timecourse

• Typically, the incubation period is about 6 to 7 days after ingesting raw infected fish.
• There have been reports of the incubation period lasting up to 30 days. After infection, dogs usually succumb within 7 to 14 days if not treated.

Diagnosis

Treatment

Prevention

Outcomes