CHAPTER XII
RELAPSING FEVER
Synonyms.—— Febris recurrens; spirillum fever; famine fever; tick fever.
Definition.—— An acute infectious disease, or, possibly, a group of infectious diseases, characterized by fever of sudden onset and, after several days (one to seven), rapid subsidence, and which may relapse at intervals of from one to seven or more days for an indefinite number of times. It is caused by spirochætes which are present in the blood during the fever and are transmitted by certain insects (bug, body-louse) or by certain ticks (Argas, Ornithodoros).
Geographical distribution.—— Relapsing fever is found in Europe, Asia, Africa, America, and probably in Australasia. In Europe it occurs in Britain and, especially, in Ireland; also in Norway, Denmark, Germany, Russia, and Turkey. In Russia there have been many epidemics; it attacked the Grand Army in the retreat from Moscow, the allied armies in the Crimea, and, also, the armies of both sides in the Russo-Turkish War. In Africa the disease has long been known in Egypt, the Soudan, and Algeria. Recently, Philip Ross, Milne, and Cook found it in Uganda, Dutton and Todd in the Congo Free State, Wellman in Angola, and Koch in German East Africa. In Asia relapsing fever is known to occur in China, in Sumatra, and in India where Carter's classical investigations were made. In America it was recognized in the United States in 1844; in 1809 it was epidemic in New York and Philadelphia. It is probably widely distributed throughout South and Central America.
From the symptoms, as far as they are known, and from the fact that they are communicated by tick bite, we are justified in conjecturing that the
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