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Rh carapata disease described by Livingstone and Kirk as endemic in the Zambesi basin, the miana disease of Persia, and a similar disease described by Alleman in Mexico may be spirochæte-produced diseases, and forms of relapsing fever.

History.—— Relapsing fever was known to Hippocrates. He describes an epidemic which he witnessed on the island of Thasos. Among other cases, he quotes those of two brothers, in one of whom the initial paroxysm lasted seven days, in the other six; the intermission in one was five days, in the other six; the relapse in both lasted five days. He further mentions the splenic enlargement, the jaundice, the liability to abortion in pregnant women, and the tendency to menorrhagia. From the time of Hippocrates onwards there is no further notice of relapsing fever in medical literature until 1770; in that year Rutty in his book on the diseases of Dublin described it. In 1873 Obermeier discovered the spirochsete. In 1897 Tictin stated that the parasite and the disease were communicated by the common bed bug; he infected a monkey with relapsing fever by subcutaneous injection of blood obtained from the stomach of a bug which had previously fed on another monkey inoculated with the disease. In 1904 Philip Ross and Milne in Uganda, and rather later, but independently, Dutton and Todd on the Congo, discovered that in Africa the spirochsete was communicated by the bite of a tick, Ornithodoros moubata. The last two observers found that the parasite could pass into the egg and larva, and so confer infective powers on the mature tick of the succeeding generation. In 1907 Mackie, in India, recorded an outbreak of relapsing fever in which lice apparently served as the transmitting agent a view favoured by the experiments of Nicolle and others, who further state that the infection can be transmitted hereditarily to the offspring of infected lice.

Etiology.—— Experiments and observation have proved that the various forms of relapsing fever are caused by Spirochceta recurrently or an allied organism