VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

CLASSIFICATION

• Depending on the diseases they produce, the vectors that transmit them, antigenic relationships, growth properties and resistance to physical and chemical agents.
  

S.No	Genus	Cell parasitised in host
1	Rickettsia	Macrophages, leucocytes and endothelial cells
2	Coxiella	Circulating leucocytes
3	Ehrlichia	Vascular endothelial cells
4	Cowdria	Vascular endothelial cells
5	Neorickettsiae	Reticular cells of lymphoid tissue

• Rickettsiales are usually parasites of alimentary tract of arthropods such as fleas, lice, ticks and mites.
• Transmission is from artropod to animal.
• The principal diseases, hosts, mode of transmission of pathogens in the Rickettsiales are:
  

Species	Disease	Main host	Transmission
R.Prowazekii	Epidemic typhus	Human	Louse
R.Mooseri	Endemic typhus	Human	Rat flea
R.Rickettsii	Rocky mountain spotted fever	Human, dogs, rabbit	Ticks (Dermacentor spp)
R.tsutsugamushi	Scrub typhus	Small rodents,Birds	Mite
Rochalimae quintana	Trench fever	Human	Louse
Coxiella burnetti	Q-fever	Human, Cattle and small ruminants	Human Contaminated dust mainly by inhalation and ingestion of contaminated milk Contact with birth fluid of ruminants Ixodes tick Animals
Ehrlichia bovis	Bovine ehrlichiosis	Cattle	Ixodes tick
Ehrlichia canis	Canine ehrlichiosis (Tropical canine pancytopenia)	Dog	Rhipicephalus sanguineus (Brown dog tick)
E.phagocytophilia	Grazing fever in cattle	Cattle &Sheep	Ixodes tick
E.risticii	Potomac horse fever (equine monocytic ehrlichiosis)	Horse	Vector not known
Cowdria ruminantium	Heart water	Cattle, Sheep, Goat and wild ruminants	Ambylomma ticks
Neorickettsia helminthoeca	Salmon poisoning	Dogs, foxes, bears, ferrets	Ingestion of salmon fish contain the infected helminth fluke(Nanophytes salmincola)