944 



ORDER I. RICKETTSIALES 



eruptive, Mediterranean or Marseilles fever 

 and probably Indian tick typhus, Kenya 

 typhus and South African tick-bite fever, 

 though the identity of the latter with bou- 

 tonneuse fever has been questioned). 



6. Rickettsia australis Philip, 1950. 

 (Agent of North Queensland tick typhus, 

 Andrew, Bonnin and Williams, Med. Jour. 

 Australia, 1946 (Aug. 24), 253; Rickettsia 

 (Dermacentroxenus) australis Philip*, in 

 Pullen, Communicable Diseases, Lea & 

 Febiger Co., 1950, 786; Ixodoxenus australis 

 Zhdanov, Opredelitel Virusov Celovska i 

 Zivotmych, Izd. Akad. Med. Nauk, U.S. 

 S.R., Moskau, 1953, 52 and 159.) 



aus.tra'lis. L. adj. australis southern. 



Minute, ellipsoidal or coccoidal forms re- 

 sembling Rickettsia prowazekii morphologi- 

 cally and in staining properties. Non-motile. 

 Gram-negative. 



Cultivation: In yolk sacs of developing 

 chicken eggs, at 32° to 35° C, poor to mod- 

 erate growth reveals cocco-bacillary, short 

 bacillary and diplo-bacillary forms. As in 

 other members of the subgenus Derma- 

 centroxenus, richer growth is reported on 

 Zinsser agar tissue culture, in which both 

 intracytoplasmic and intranuclear parasit- 

 ism is readily demonstrated. 



Immunology: Duration of immunity is 

 unknown in man in this recently discovered 

 malady. Recovered guinea pigs remain 

 solidly immune for at least 8 months and 

 may show partial to complete immunity 

 within 50 days to heterologous challenge 

 with strains of Rickettsia conorii and R. 

 typhi but no immunity toR. conorii 8 months 

 or longer after recovery. No cross immunity 

 was found with R. isutsugnmushi in white 

 mice. 



Serology: Convalescent sera of patients 

 contained agglutinins for Proteus OXig or 

 0X2 but none for OXK. The sera failed to 

 fi.x complement in the presence of rickettsial 

 antigens of epidemic or murine typhus. 



boutonneuse fever and American spotted 

 fever, though homologous fixation was re- 

 ported. Sera of recovered rabbits or guinea 

 pigs have shown this agent to be a distinct 

 member of the spotted-fever group in com- 

 plement-fi.xation tests and to have a higher 

 homologous than heterologous reaction in 

 certain of these tests. 



Pathogenic for man; infected guinea pigs 

 develop fever and scrotal reactions. White 

 mice do not usually show signs of infection. 

 In contrast to R. typhi, R. australis does not 

 persist in the brains of white rats, though 

 male rats may develop scrotal reactions 

 when injected with cultures. 



Lethal effect: Intravenous injection of 

 laboratory mice with cultures has not 

 demonstrated the presence of a to.xin, in this 

 respect resembling Rickettsia akari. 



Source: Observed by Andrew et al. (op. 

 cit., 1946, 253) in smears of peritoneal exu- 

 date of white mice injected with blood of 

 two patients in North Queensland, Aus- 

 tralia. 



Habitat: Tick transmission has not been 

 demonstrated but has been presumed by the 

 finding of either larval or adult Ixodes 

 holocijclus on a few patients. The occurrence 

 of primary eschars on patients implicates a 

 probable acarine vector, but Dermacentor 

 andersoni, a natural vector of Rickettsia 

 rickettsii, does not experimentally transmit 

 R. australis. Complement-fixing antibodies 

 have been found in four kinds of native 

 Queensland marsupials and in one species 

 of rat. 



7. Rickettsia akari Huebner et al., 1946. 

 (Huebner, Jellison and Pomerantz, U. S. 

 Public Health Rep., 61, 1946, IQ82; Rickettsia 

 (Dermacentroxenus) akari Philip and Hughes, 

 Amer. Jour. Trop. Med., ^8, 1948, 705; 

 Acaroxenus varioleidis (sic) Zhdanov and 

 Korenblit, Jour. Microbiol., Epidemiol, 

 and Immunobiol. (Russian), No. 9, 1950, 

 ■i2; Gamasoxenus muris Zhdanov, Opredelitel 



* Publishing date, June 16, 1950. By coincidence this name, including the same subgenus, 

 was published by Zhdanov and Korenblit the same year (Jour. Microbiol., Epidemiol, and 

 Immunobiol. (Russian), No. 9, 1950 (reprint states September), 42). This name had also 

 been used by these authors in a report to a scientific conference (Ukranian Int. imeni 

 Mechnikov, Khar'kov, October 11, 1949), although, according to Rule 11, it was not eff"ec- 

 tively published at that time so far as known. 



