1088 



MANUAL OF DETERMINATIVE BACTEEIOLOGY 



Serology : Distinguishable from Rick- 

 ettsia prowazekii and Rickettsia typhi by 

 complement fixation and agglutination 

 with specific antigens. Distinguishable 

 from Rickettsia conorii by complement 

 fixation, though some degree of cross 

 fixation indicates antigenic relationship. 

 Has common antigenic factor with Pro- 

 teus 0X19 but not distinguishable from 

 Rickettsia prowazekii and Rickettsia 

 typhi by Weil-Felix test. 



Resistance to chemical and physical 

 agents : Readily inactivated by heat and 

 chemical agents. Destroyed by a tem- 

 perature of 50°C in 10 minutes, and by 

 0.5 per cent phenol and 0.1 per cent 

 formalin. Destroyed by desiccation in 

 about 10 hours. 



Pathogenicity : Pathogenic for man, 

 monkeys and guinea pigs. Rabbits and 

 white rats are moderately susceptible. 

 Animals susceptible in varying degree.s 

 include species of ground squirrels, tree 

 squirrels, chipmunks, cotton-tail rabbits, 

 jack rabbits, snowshoe rabbits, marmots, 

 wood rats, weasels, meadow mice and 

 deer mice. In Brazil the opossum, rab- 

 bit, dog and cavy have been found natu- 

 rally infected and the Brazilian plains 

 dog, capybara, coati and certain bats 

 are also susceptible. Sheep are mildly 

 susceptible. 



A febrile reaction occurs in guinea pigs 

 with typical scrotal lesions, involving 

 petechial hemorrhages in the skin, which 

 may become necrotic. Virulent strains 

 kill 80 to 90 per cent of the animals, 

 milder strains kill 20 to 25 per cent. 

 Passage in guinea pigs is accomplished by 

 transfer of blood from infected animals. 

 A febrile reaction accompanied by exan- 

 thema occurs in man. Mortality is high 

 in some localities, low in others. 



Source : Seen by Ricketts (Jour. Amer. 

 Med. Assoc, 52, 1909, 379) in the blood 

 of guinea pigs and monkeys experimen- 

 tally infected with Rocky Mountain 

 spotted fever and in the salivary glands, 

 alimentary sac and ovaries of infected 



female Dcrmacentor ticks and in their 

 ova. 



Habitat: Infected wood tick {Derma- 

 centor andersoni) and the dog tick {Der- 

 macentor variabilis), also the rabbit tick 

 (Haemaphysalis leporis-palustris) , Am- 

 blyonima hrasiliensis, Amhlijomma 

 cajennense, Amblyonwia striatum, Am- 

 blyomma americanuni and Ixodes denta- 

 tus. A number of ticks belonging to the 

 genera Amblyomma, Dermacentor, Rhipi- 

 cephalus, Ornithodoros and Haema- 

 physalis have been experimentally 

 infected. The virus is transmissible 

 through the ova of female ticks. The 

 etiological agent of Rocky Mountain 

 spotted fever, Sao Paulo exanthematic 

 typhus of Brazil, Tobia fever of Colombia 

 and spotted fever of Minas Geraes which 

 are all transmitted to man by the bite of 

 infected ticks. 



i. Rickettsia conorii Brumpt. 



(Brumpt, Compt. rend. Soc. Biol., Paris, 

 110, 1932, 1199; Rickettsia megawi var. 

 pijperi do Amaral and Monteiro, Mem. 

 Inst. Butantan, 7, 1032, 361 ; Rickettsia 

 blanci Caminop^tros, l'"' Cong. Internat. 

 Hyg. Mediterr., Rapports et Compt. 

 rend., 2, 1932, 202; Dermacentroxenus 

 rickettsi var. pijperi Mason and Alexan- 

 der, Onderst. Jour. Vet. Sci. and An. 

 Indust., 13, 1939, 74; Dermacentroxenus 

 rickettsi var. conori Mason and Alex- 

 ander, ibid. ; Dermocentroxenus conori 

 Steinhaus, Insect Microbiology, 1946, 

 339.) Named for A. Conor who with A. 

 Bruch published in 1910 the first clini- 

 cal description of boutonneuse fever. 



Resembles Rickettsia rickettsii. In 

 the tick, diplococcoid and diplobacillary 

 forms predominate, though when the 

 rickettsiae occur in compact masses they 

 are smaller and more coccoid. In tissue 

 cultures the organisms are lanceolate, 

 diplococcoid, and diplobacillary, oc- 

 curring in the nuclei as well as in the 

 cytoplasm of the cells. Size 0.3 to 0.4 

 by 1 to 1.75 microns. Non-motile. 



Stain purplish with the Giemsa stain, 



