1094 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



Genus III. Cowdria Bengtson, gen. nov. 



Named for E. V. Cowdry who first described the organism in heartwater of three 

 ruminants, sheep, goats and cattle. 



Small pleomorphic, spherical or ellipsoidal, occasionally rod-shaped organisms, 

 occurring intracellularly in ticks. Gram-negative. Have not been cultivated in 

 cell-free media. Parasites which are the etiological agent of heartwater of cattle, 

 sheep and goats. 



The type species is Cowdria ruminantiwn (Cowdry) Bengtson. 



1. Cowdria ruminantiixm (Cowdry) 

 Bengtson, comb. nov. (Rickettsia rumi- 

 naniium Cowdry, Jour. Exp. Med., 4^, 

 1925, 231; Rickettsia (Coivdria) rurni- 

 nantiu7n Moshkovsky, Uspekhi Soure- 

 mennoi Biologii (Russian) (Advances in 

 Modern Biology), 19, 1945, 18.) From 

 M. L. Ruminantia, the cud-chewing 

 mammals. 



Differ morphologically from typical 

 rickettsiae, showing usually spherical 

 and ellipsoidal forms; occasionally bacil- 

 lary forms. Irregular pleomorphic forms 

 occur. Grow in the cytoplasm of cells, 

 sometimes in densely packed masses. 

 Size of cocci from 0.2 to 0.5 micron in 

 diameter in the endothelial cells of ani- 

 mals, 0.2 to 0.3 micron in diameter in 

 ticks. Bacillary forms 0.2 to 0.3 by 0.4 

 to 0.5 micron and pairs 0.2 by 0.8 micron 

 in ticks. Non-motile. 



Stain blue with the Giemsa stain and 

 can also be stained by methylene blue 

 and other basic aniline dyes. Gram- 

 negative. 



Cultivation not reported. 



Immunology : Immunity incomplete 

 after recovery from the infection. The 

 organisms are found in the tissues long 

 after recovery. There is some evidence 

 of a variety of strains. 



Pathogenicity: Pathogenic for goats, 

 sheep and cattle. Transmissible to goats 

 by inoculation of infected blood intra- 

 jugularly. The most characteristic le- 

 sion is the hydropericardium of infected 

 animals. The only small animal shown 

 to be susceptible is the ferret. 



Source : Seen in the endothelial cells 

 of renal glomeruli and in the endothelial 

 cells of the cerebral cortex of animals suf- 



fering from heartwater and in the tick, 

 Amhlyoynma hebraeuni. 



Habitat : The bont tick {Amhlyomma 

 hebraeiun) and also Amblyomma variega- 

 tum. When the tick is infected in the 

 larval state, it can transmit the infection 

 to the nymphal and adult stages, but the 

 disease is not transmissible through the 

 ova of the adult female tick. The etio- 

 logical agent of heartwater in sheep, 

 goats and cattle in South Africa. 



Appendix I: Further studies of the 

 organism of trench fever are required be- 

 fore the relationship of Rickettsia quin- 

 iana to the other more firmly established 

 species of rickettsiae can be determined. 

 Therefore, it is placed in this appendix. 



1. Rickettsia quintana Schminke. 

 (Schminke, Miinch. med. Wchnschr., 64, 

 July 17, 1917, 961; Rickettsia wolhynica 

 Jungmann and Kuczynski, Ztschr. klin. 

 Med., 85, 1918, 261; Fossilis quintana 

 suggested as a possible subspecies "if 

 necessary" by Megaw, Trop. Dis. Bull., 

 40, 1943, 828.) 



Probable synonym : Rickettsia pediculi 

 Munk and da Rocha-Lima, Miinch. med. 

 Wchnschr., ^4, 1917, 1423. 



Coccoid or ellipsoidal organisms, 

 often occurring in pairs, more plump and 

 staining more deeply with the Giemsa 

 stain than Rickettsia prowazekii. Da 

 Rocha-Lima gives their size as 0.2 to 0.4 

 micron by 0.3 to 0.5 micron. In lice 

 appear as short rods, frequently in pairs 

 and often bipolarly stained. Non-mo- 

 tile. 



Stain reddish-violet with the Giemsa 

 stain. Gram-negative. Occur extra- 



