THE SPIROCHÆTES OF THE BLOOD.
There are at least two important human parasites included hereunder:—
(a) Spirochæta recurrentis (=S. obermeieri), (b) Spirochæta duttoni.
More is known of the life-cycle of Spirochæta duttoni, and it will be convenient to consider that first.
Spirochæta duttoni, Novy and Knapp, 1906.
The specific name duttoni was also given, independently, to this parasite in 1906 by Breinl and Kinghorn.
S. duttoni is the pathogenic agent of African tick fever in man, prevalent in the Congo State and other parts of Africa. The full-grown organism is about 16 µ to 24 µ long, and has pointed ends. It is 0·25 µ to 0·5 µ broad. P. H. Ross and Nabarro were among the earliest to see a spirochæte in the blood of patients in Uganda. It is transmitted by the tick, Ornithodorus moubata.
In the blood of the patient some of the spirochætes may show, after staining, lighter and darker portions (chromatin dots) and evidence of the possession of a very narrow membrane (fig. 54). The mode of division has already been discussed. Periodicity in the direction of division was first described by Fantham and Porter,[145] (1909). Just before the crisis in African tick fever, Breinl has stated that S. duttoni becomes thinner in the spleen and bone-marrow and rolls up into skein-like forms, which are surrounded by a thin “cyst” wall (probably the periplast). Such occur in apyrexial periods. Inside the cyst the spirochæte breaks up into granules. Balfour and Sambon have described somewhat similar rolled up forms, breaking into granules, inside the red blood cells of Sudanese fowls in the case of S. granulosa (possibly only a variety of S. gallinarum). The intracorpuscular stage is not definitely established.
