FAMILY I. RICKETTSIACEAE 



951 



1. Cowdria ruminantium (Cowdry, 

 1925) Moshkovskiy, (1945) 1947. {Rickettsia 

 ruminantium Cowdry, Jour. Exp. Med., ^2, 

 1925, 'IZl; Rickettsia (Cowdria) ruminantium 

 Moshkovskiy, Uspekhi Souremennoi Biol. 

 (Russian) (Advances in Modern Biology), 

 19, 1945, 18; Cowdria ruminantium Moshkov- 

 skiy, Science, 106, 1947, 62; Kurlovia (Cow- 

 dria) ruminantium Zhdanov, Opredelitel 

 Virusov Celovska i Zivotmych, Izd. Akad. 

 Med. Nauk, U.S.S.R., Moskau, 1953, 56 and 

 166.) 



ru.mi.nan'ti.um. M.L. neut.gen.pl.n. ru- 

 minantium of Ruminantia, formerly an 

 ordinal name for cud-chewing mammals. 



Differ morphologically from typical ty- 

 phus-like rickettsiae, showing u.sually 

 spherical and ellipsoidal forms, occasionally 

 bacillary forms. Irregular pleomorphic 

 forms occur. Grow in the cytoplasm but not 

 in the nuclei of cells, sometimes in densely 

 packed masses. Cocci measure 0.2 to 0.5 

 micron in diameter in the endothelial cells 

 of animals and 0.2 to 0.3 micron in diameter 

 in ticks. In ticks bacillary forms are 0.2 to 

 0.3 by 0.4 to 0.5 micron and pairs are 0.2 

 by 0.8 micron. Non-motile. Stain blue with 



Giemsa's stain; 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 

 (premunition). There is some evidence of a 

 variety of strains. 



Pathogenic for goats, sheep and cattle. 

 Transmissible to goats by inoculation of 

 infected blood intrajugularly. The most 

 characteristic lesion is the hj^dropericar- 

 dium of infected animals. The only small 

 animal shown to be susceptible is the ferret. 



Source: Observed in the endothelial cells 

 of renal glomeruli and in the endothelial 

 cells of the cerebral cortex of animals suffer- 

 ing from heartwater; also observed in the 

 tick Amblyomma hebraeum. 



Habitat: Found in the bont tick (A. 

 hebraeum) and also in A. variegatum, in 

 which the infection has been shown to be 

 transstadial but not transovarial. The eti- 

 ological agent of heartwater in sheep, goats 

 and cattle in South Africa. 



Genus V. Neorickettsia Philip et al., 1953. 



(Philip, Hadlow and Hughes, Riassunti delle Comunicazioni, VI Congresso Internaz. di 



Microbiol., Roma, 2, 1953, 256; also see Exp. Parasitol., 3, 1954, 336; and Atti del 



VI Congresso Internaz. di Microbiol., Roma (1953), 4, 1955, 70.) 



Ne.o.ri.ckett'si.a. Gr. prefix neo- new; M.L. fem.n. Rickettsia type genus of family 

 Rickettsiaceae; M.L. fem.n. Neorickettsia the new Rickettsia. 



Small, coccoid, sometimes pleomorphic (in the form of short rods, crescents and even 

 rings), intracytoplasmic organisms which occur in the reticulo-endothelial cells of certain 

 mammals and in tissues of at least mature fluke vectors. No intranuclear forms have been 

 observed. Non-filterable. Non-motile. Not cultivable on cell-free media. The etiological 

 agent of a helminth-borne disease of canines. 



The type species is Neorickettsia helminthoeca Philip et al. 



1. Neorickettsia helminthoeca Philip 

 et al., 1953. (Neorickettsia hehnintheca (sic) 

 Philip, Hadlow and Hughes, Riassunti delle 

 Communicazioni, VI Congresso Internaz. 

 di Microbiol., Roma, 2, 1953, 256; also see 

 Exp. Parasitol., 3, 1954, 336; Neorickettsia 

 hehnintheca (sic) Philip, Hadlow and 

 Hughes, Atti del VI Congresso Internaz. di 

 Microbiol., Roma (1953), 4, 1955, 70.) 



hel.min'thoe.ca. Gr. noun helmins, hel- 



minthis worm; Gr. noun oicus house; M.L. 

 adj. helminthoecus worm-dwelling. 



Minute, coccoid and ellipsoidal forms to 

 short rods and clubs, occasionally crescentic 

 and even ring-like. Often form morula-like 

 clusters either singly or in multiple colonies 

 in the cytoplasm of reticuloendothelial cells 

 of infected canines. The most common coc- 

 coid forms range from 0.3 to 0.4 micron in 

 diameter. Non-filterable. Non-motile. In 



