268 
Spirochaetosis 
those in which mouhata occurs, the latter being a purely African 
species. 0. savignyi, which is indistinguishable from moubata at 
a casual glance, and which also occurs in Africa, at Aden and in India, 
has been found by Brumpt to convey a spirochaete derived from cases 
of human relapsing fever occurring in Abyssinia. 0. turicata is 
suspected in connection with relapsing fever in Colombia, and 0. talaje, 
I have no doubt, might play a similar part in Mexico and Central 
America whence I have received specimens. Lately, both Leishman 
and myself have received specimens of 0. tholozani from Quetta, India, 
where it was suspected of being a vector, but experiments carried out 
with the few living examples which reached Leishman have proved 
negative. Again, from the fact that A. persicus, as tested experi¬ 
mentally by Sergent and Foley (1908), in the Sud-Oranais, Africa, serves 
as a host for spirochaetes of human origin, we may conclude that this 
species, which frequently attacks man, may also communicate relapsing 
fever under suitable conditions. Sergent and Foley found the spiro¬ 
chaetes present in the coelomic fluid of this tick for two days, after 
which they disappeared. 
That neither the tick nor the spirochaete is specifically adapted to 
the other is a matter of considerable importance which has been 
revealed by recent research. In view of the morphological similarity of 
the supposedly different species of spirochaetes and their individual 
variations in virulence, we may well doubt if any of the “species” are 
valid. As I pointed out four years ago, the various specific names given 
to the spirochaetes causing relapsing fever in man may be used merely 
for convenience to distinguish strains or races of different originf They 
cannot be regarded as valid names, in the sense of scientific nomen¬ 
clature, for virulence and immunity reactions are not adequate tests of 
specificity. Under experimental conditions 0. moubata has served for 
the transmission not only of S. duttoni and two other so-called species, 
S. recurrentis and S. novyi, which affect man in the Old and New 
World respectively, but it has also been found to transmit the fowl 
spirochaete. S. duttoni, moreover, has been successfully transmitted to 
rats by Haematopinus spinulosus, the common rat-louse. There is every 
reason to suppose that a spirochaete capable of adapting itself either to 
a tropical African tick or to a rat-louse occurring all over the world, will 
be able to accommodate itself to a variety of vertebrate hosts; and we 
know in fact, from laboratory tests, that a considerable number of animals 
1 S. recurrentis may be the only true species; the name recurrentis has priority over 
S. ohermeieri. Other so-called species are duttoni, rossi or kochi, novyi, hcrhera, carteri, etc. 
