History.—Although Hippocrates described the clinical features of relapsing fever quite accurately this knowledge seems to have been lost until about the eighteenth century.
The causative spirochaetes were first seen by Obermeier in the blood of a patient in 1868 but he did not publish his discovery until 1873.
Ross and Milne, in 1904, found that African tick fever was a spirillar fever while Dutton and Todd established the fact of its transmission by ticks.
Geographical Distribution.—Relapsing fever was epidemic in the U. S. in 1869, since which time it has not reappeared. There have been many epidemics in Ireland, Russia, Turkey and other parts of Europe. It was a disease of importance during the Balkan War of 1912-1913. China and India have frequently been visited by epidemics as well as the Philippine Islands and the Dutch East Indies. Uganda, Congo State and German East Africa, as well as Egypt and Algeria, are important centers. There is also a relapsing fever of Colombia and Central America.
Etiology and Epidemiology
Etiology.—Relapsing fevers are caused by organisms generally considered as protozoal in their nature and belonging to the flagellates.
Fig. 36.—Spirochaetes of relapsing fever from blood of man. (Kolle and Wassermann.)
Transmission by the tick.—The generic name Spiroschaudinnia is preferred by some to the more commonly accepted Spirochaeta. Recently, authorities give these organisms the name Spironema. East and West African relapsing fever, or tick fever, is caused by Spironema duttoni and the transmission is through the bite of an argasine tick, Ornithodoros moubata. Not only does the tick itself become infected by the taking in of blood-containing spirochaetes but likewise transmits the infection to its progeny. Leishman considers that when the spirochaetes are taken into the alimentary tract of the tick there is a breaking up of the spirochaetes into small granules which reach the Malpighian tubules. They also invade the ovary and the ova. It was thought that these granules were the infecting agents and that they were excreted in the fluid of the coxal glands or passed out with the faeces. More recently it has been claimed that these granules have no relation to the infection, which is due to spirochaetes as such.