938 



ORDER I. RICKETTSIALES 



Serology: Strains from various parts of 

 the world are closely related as determined 

 by complement fixation, are distinguishable 

 from other rickettsiae by agglutination, 

 complement fixation and precipitin tests, 

 have a common antigenic factor (alkali - 

 stable polysaccharide) with Proteus OX19 

 and have a soluble antigen in yolk culture. 



Lethal effect: Heavily infected yolk-sac 

 cultures injected intravenously or intra- 

 peritoneally are fatal to white mice in a few 

 hours. The toxin, in neutralization tests, has 

 been shown to be specific and is distin- 

 guishable from murine typhus toxin. 



Pathogenic for man, apes, monkeys, 

 guinea pigs, cotton rats, gerbilles and the 

 louse {Pediculus humanus). Inapparent 

 infections occur in white mice, white rats 

 and rabbits. A characteristic febrile reac- 

 tion with no mortality and usually without 

 scrotal swelling occurs in the guinea pig. 

 Passage in guinea pigs is accomplished by 

 transfer of blood or brain from infected ani- 

 mals; causes a febrile disease with exan- 

 thema and high mortality in man. Does not 

 persist for extended periods in brains of 

 white rats compared to endemic (murine) 

 typhus. A characteristic skin reaction can 

 be produced in recovered rabbits and man. 



Source: Observed sparingly in the blood 

 of typhus patients and abundantly in smears 

 of epithelial cells of the intestinal tracts of 

 lice fed on typhus patients. 



Habitat : Found in the body louse {Pedic- 

 ulus hmnanus var. humanus), head louse 

 (P. humanus var. capitis) and monkey 

 louse {Pedicinus longiceps). The etiological 

 agent of epidemic typhus (European typhus, 

 classical typhus, typhus exanthematicus). 

 Man is the probable animal reservoir. 



2. Rickettsia typhi (Wolbach and Todd, 

 1920) Philip, 1943. {Dermacentroxenus typhi 

 Wolbach and Todd (not Tood), Ann. Inst. 

 Past., 34, 1920, 158; minute intracellular 

 bodies, Mooser, Jour. Inf. Dis., 43, 1928, 

 261; Rickettsia manchuriae Kodama, Taka- 

 hashi and Kono, Saikingaku-Zasshi (Jap.), 

 No. 426, 427, Aug. and Sept., 1931; see 

 Kodama, Kono and Takahashi bibliog- 

 raphy, Kitasato Arch. Exp. Med., 9, 1932, 

 95; Rickettsia mooseri Monteiro, Mem. Inst. 

 Butantan, 6, 1931, 97 (pub. July, 1932); 



see Franco do Amaral and Monteiro, bib- 

 liography, Mem. Inst. Butantan, 7, 1932, 

 367; Rickettsia exanthematofebri Kodama, 

 Kitasato Arch. Exp. Med., 9, 1932, 360; 

 Rickettsia muricola Monteiro and Fonseca, 

 Brasil Med., 46, 1932, 1022; Rickettsia murina 

 and Rickettsia fletcheri Megaw, Trans. Roy. 

 Soc. Trop. Med. Hyg., 29, 1935, 105; Rickett- 

 sia prowazeki var. mooseri Pinkerton, Para- 

 sitology, 28, 1936, 185; Rickettsia prowazeki 

 subsp. typhi Philip, Amer. Jour. Hyg., 37, 

 1943, 304; Rickettsia typhi Philip, loc. cit.; 

 not Rickettsia typhi Franco do Amaral and 

 Monteiro, Rev. Sud. Amer. de Med. et 

 Chirug., 4, 1933, 806; Rickettsia murina 

 mooseri Veintemillas, Tratado sobre rickett- 

 siasis, etc., Bolivia, 1944, 100.) 



ty'phi. Gr. noun typhus cloud, hence 

 stupor arising from fever; M.L. noun typhus 

 fever, typhus; M.L. gen. noun typhi of 

 typhus. 



Resembles Rickettsia prowazekii morpho- 

 logically and in staining properties but 

 averages slightly smaller, 0.45 by 1.0 micron 

 with individual variation of 0.35 to 0.6 by 

 0.7 to 1.3 microns, under the electron 

 microscope. Non-motile. Gram-negative. 



Giroud (1952) proposed the term "typhus 

 murin tropical" for a virulent form in Equa- 

 torial Africa. 



Cultivation : May be cultivated in plasma 

 tissue culture of mammalian cells, in modi- 

 fied Maitland media with and without agar, 

 in fleas and lice, in the peritoneal cavities 

 of X-rayed rats, in the lungs of white mice 

 and of white rats following intranasal 

 inoculation, in the lungs of rabbits follow- 

 ing intratracheal inoculation and in the 

 chorio-allantoic membrane and the j'olk sac 

 of the chick embryo. 



Optimum temperature, 35° C. in chick- 

 embryo cells. 



Immunology: Prolonged immunity in 

 man and animals following infection. Com- 

 plete cross immunity between epidemic and 

 endemic typhus in guinea pigs recovered 

 from infections with Rickettsia prowazekii 

 and R. typhi. No cross immunity between 

 endemic typhus and Rocky Mountain spotted 

 fever, Q fever or tsutsugamushi disease 

 in guinea pigs. 



Serology: Distinguishable from the 

 rickettsiae of spotted fever, Q fever and 



