A. Balfour 
293 
3 INCIDENCE OF LEPTOSPIRA ICTEROHAEMORRHAGIAE AND MECHANISM 
OF ITS TRANSMISSION. 
The publication in 1919 of the very complete monograph by Martin and 
Pettit entitled Spirochetose Icterohemorragique has rendered any detailed con¬ 
sideration of the literature superfluous. There have, however, been some 
important papers since the appearance of the French work and to these, 
when necessary, attention will be directed. 
Technique. 
j 
At the autopsies when urine was present in the bladders of the rats it 
was examined by the dark field method. In addition it was customarv to 
«/ 
make smears from the kidney which were stained by Giemsa, while in a few 
of the earlier cases portions of the kidney were stained in block by the Levaditi 
method. As a further confirmatory test on a good many occasions the urine 
or an emulsion of kidney and liver tissue were inoculated into guinea pigs 
intraperitoneally. 
The results of these procedures were on the whole confirmatory though, 
as other observers have found, a certain proportion of guinea pigs cannot be 
infected, either because they are insusceptible or possibly because the particular 
strain of leptospira possesses no pathogenicity for these animals. In cases 
where infected urine was employed it is conceivable, as suggested by Uhlenhuth 
and Zuelzer, that the urine had itself exerted a detrimental effect on the 
organism, rendering it innocuous. These observers believe that the acidity of 
urine is a potent factor in weakening or killing the leptospira. There must 
also be considered the view put forward by Foulerton that infection with 
Leptospira icterohaemorrhagiae can only be definitely determined by guinea 
pig inoculation. On these grounds he rejects the work of Coles at Bournemouth 
in 1918. This is doubtless true, but, as pointed out, the inoculation test is by 
no means a certain one and, as the presence of a leptospira-like organism can 
after sufficient experience readily be detected in tissue emulsion and in the 
urine by the dark field method and also in stained smears and sections, and 
as no other organism morphologically similar is known to infect rats in this 
country, it is reasonable to assume that in the case of positive findings by these 
various methods one is actually dealing with Leptospira icterohaemorrhagiae. 
If positive infections with guinea pigs are alone accepted as a criterion of 
infection there can be no doubt that, for the reasons above stated, cases will 
be missed. 
A record of part of this work has already been published by A. C. Stevenson 
in a paper entitled “The Incidence of a Leptospira in the Kidneys and of 
Parasites in the Intestines of One Hundred Wild Rats examined in England.” 
He showed by a comparison of kidney smears and kidney sections that, in 
the hands of an experienced observer, the smear method sufficed to. reveal the 
presence of leptospira. 
