Genus Neorickettsia Flashcards
Neorickettsia helminthoeca
Salmon poisoning disease of dogs
Salmon poisoning disease of dogs
Transmission—snail-fish-dog cycle
N. helminthoeca is found in all stages of the fluke, Nanophyetus salmincola
Released infected cercariae penetrate salmonid fish, developing into metacercariae
Infected raw fish ingested by dog
Metacercariae develop into adult intestinal flukes
Adult flukes release N. helminthoeca
Salmon Poisoning Disease
Pathogenesis
Release of N. helminthoeca; invasion of bloodstream
Replication in intestinal epithelial cells and lymphatic tissues [lymphadenopathy]
Inflammation of Peyer’s patches, etc
Salmon Poisoning Disease
Clinical Findings
Fever, diarrhea or dysentery, vomiting, weight loss and dehydration
Salmon Poisoning Disease
Diagnosis
Consumption of raw fish
Fluke ova in feces
Examination of smears using Giemsa stain
Salmon Poisoning Disease
Immunity
Recovered dogs may be immune for life
Neorickettsia risticii
Potomac Horse Fever or Equine Neorickettsiosis
Potomac Horse Fever or Equine Neorickettsiosis
Epidemiology
N. risticii infects cercariae and metacercariae of the fluke A. oregonense
Infected cercariae are ingested by the larvae of caddis fly, mayfly, etc.
Ingestion of infected, dead adult caddis flies and mayflies by horse feeding on pasture
Potomac Horse Fever
Pathogenesis
Monocyte-associated bacteremia
Replication in epithelial cells of the large intestines
Colitis and typhlitis
Potomac Horse Fever
Clinical Findings
Fever, profuse, watery diarrhea
Colic, subcutaneous edema of the limbs and ventral abdomen, and laminitis
Case fatality rate: 5-30%
Potomac Horse Fever
Diagnosis
Giemsa-stained blood smear
Potomac Horse Fever
Serology
Rise in antibody titer
Potomac Horse Fever
Immunity
Recovered animals may be immune for up to 20 months
Horses are vaccinated with an inactivated vaccin
