952 



ORDER I. RICKETTSIALES 



node imprint preparations, these organisms 

 stain bluish with Giemsa's stain and faintly 

 by Castaneda's method. Gram-negative. 



Cultivation: Will not grow in ordinary 

 bacteriological media or in embryonated 

 chicken eggs. Has been grown in certain 

 tissue-culture explants from infected dog- 

 node tissues. 



Immunology: Recovered dogs are solidly 

 immune to reinfection, but mild febrile 

 relapses may occur during which infection 

 is recoverable from the blood. Guinea pigs 

 injected with this agent are not cross- 

 immunized against Rocky Mountain spotted 

 fever, endemic typhus or Q fever. Natural 

 resistance in dogs has not been observed, 

 but dogs have been immunized by infectious 

 materials of reduced virulence which have 

 caused mild or inapparent infections. 



Serology: Attempts to prepare a usable 

 antigen from heavily infected dog nodes 

 have not been successful, and no other 

 source of antigen is yet available. Hyper- 

 immunized dogs and rabbits have shown no 

 common antigenic factor with strains of 

 Proteus vulgaris. 



Resistance to chemical and physical 

 agents: Inactivated within a few hours in a 

 saline suspension at room temperature. Dog 

 nodes frozen at —20° C. have remained 



infectious for at least 158 days but survive 

 more consistently at — 70°C. Survival under 

 lyophilization is short. 



Antibiotic therapy: Symptoms in ill dogs 

 quickly alleviated by oral administration 

 of aureomycin or terramycin, as little as 

 250 mg in 15-pound beagles. Sulfonamids 

 also effective in treatment. 



Pathogenicity: Untreated dogs show up- 

 wards of 90 per cent mortality after feeding 

 on infected fish or when injected with in- 

 fected dog tissues and blood. Foxes and coy- 

 otes are also susceptible. Causes mild re- 

 sponse in guinea pigs, hamsters and white 

 mice; this response is retrogressive on 

 passage and is not maintained. Raccoons 

 and mink do not show clinical reactions to 

 attempted experimental infections. Trout 

 are not infected by injection of infected dog- 

 node suspensions. 



Source: First observed in node-imprint 

 preparations of experimentally infected 

 dogs by Cordy and Gorham (Amer. Jour. 

 Path., ^6, 1950, 457). 



Habitat: Found in the intestinal trema- 

 tode Nanophyetus salmincola (Chapin), 

 which probably acts as the natural reservoir 

 of infection. The etiological agent of a sal- 

 mon-poisoning disease of canines. 



TRIBE III. WOLBACHIEAE PHILIP, 1955. 



(Bact. Rev., 19, 1955, 271.) 



Wol.ba.chi'e.ae. M.L. fem.n. Wolbachia type genus of the tribe; -eae ending to denote a 

 tribe; M.L. fem.pl. n. Wolbachieae the Wolbachia tribe. 



Includes many species heretofore assigned to the genus Rickettsia which are rickettsia- 

 like in growth and in morphological and staining properties and which are mostly intracel- 

 lular symbiotes or parasites of various species of arthropods, sometimes occupying special 

 tissues or mycetomes. Characterization has often been not so adequate as in the preceding 

 forms that are pathogenic for vertebrates, and differentiation has been arbitrarily assigned 

 chiefly on the basis of presumed host-specificity in arthropods, though differences in devel- 

 opment and morphology are often noted. 



At present three genera are recognized in the tribe Wolbachieae; however, future knowl- 

 edge may show that a better and more satisfactory arrangement is possible. 



Key to the genera of tribe Wolbachieae. 



I. No known filterability; no reported association with intracellular crystalline inclusions. 

 A. Symbiotic to highly pathogenic; no mycetomes produced in hosts. 



Genus VI. Wolbachia, p. 953. 



