G46 FILTERABLE VIRUSES— RICKETTSIA 
of patients. Jungmann and Kuczynski' found diplobacillary bodies 
which resembled somewhat hemorrhagic septicemia bacilli. Houston 
and McClov' isolated Micrococcus ovalis (enterococcus) from a series 
of trench fever cases. x4rkwright, Bacot and Duncan"* found small 
globoid and bacilloid bodies in a series of lice obtained from the persons 
of cases of trench fever. These bodies measured about 0.3 micron in 
diameter and from 0.3 to 1.5 microns in length. They were considered 
to be members of the group of the Rickettsia. Toepfer'* had previously 
reported the occurrence of the same, or similar bodies in blood films 
obtained from trench fever cases, and Minik and da Rocha-Lima^ had 
studied the Rickettsia in lice obtained both from cases of trench fever 
and typhus. They believed the Rickettsia of trench fever infected lice 
were extracellular, whereas the Rickettsia of lice infected with typhus 
(Rickettsia prowazeki) were intracellular. These observations suggest 
that Rickettsia prowazeki may actually infect lice, as well as man. 
Schmincke'' called the Rickettsia found in association with trench fever 
Rickettsia quintana.^ The name Rickettsia wolhynica has also been 
bestowed upon this member of the group. Wolbach, Todd and Pal- 
frey*^ have presented evidence which led them to believe Rickettsia 
pediculi, the name given by Munk and da Rocha-Lima to the organisms 
found by them in lice infected from trench fever cases, to be identical 
with Rickettsia quintana and Rickettsia wolhynica. This seems quite 
probable, and if it is confirmed, it will simplify the nomenclature very 
materially. Available evidence suggests quite definitely that the 
Rickettsia have an etiological relationship to trench fever. ^ 
There is some evidence that the virus may belong to the group of 
filter passers. Both the American Red Cross Commissions'^ and Brad- 
ford, Bashford and Wilson^^ have reported successful infections of 
volunteer subjects with filtrates from the blood of trench fever patients. 
The virus is said to resist an exposure to a temperature of 60° C. 
moist heat, but not 70° C. 
Immunity, if such exists after recovery, appears to be of brief 
duration. 
Delousing is the most direct hygienic measure to prevent the spread 
of trench fever. 
Rocky Mountain Spotted Fever.— Rocky Mountain spotted fever 
is defined^^ as "an acute specific infectious endangitis, chiefly of the 
1 Deutsch. med. Wchnschr., 1917, 64, 359. 
2 Lancet, 1916, ii, 632. ' British Med. Jour., 1918, ii, 307. 
" Miuichen. med. Wchnschr., 1918, 63, 1495. 
5 Ibid., 1917, 64, 1422. " Ibid., 64, 961. 
" Werner and Benzler: Miinchen. med. Wchnschr., 1917, 64, 695. Werner, Benzler 
and Weise: Ibid., 1916, 63, 1369. 
8 The Etiology and Pathology of Typhus, 1922, p. 200. 
9 Arkwright, Bacot and Duncan: Jour. Hyg., 1919-1920, 18, 76. 
1" Loc. cit. " British Med. Jour., 1919, i, 599, 601, 602. 
12 Wolbach: Studies on Rocky Mountain Spotted Fever (Jour. Med. Res., 1919, 41, 
1-197). (This monograph is the authoritative publication upon this disease, both with 
res])ect to history, etiology', pathology and clinical aspects.) 
