1.Relapsing fever of man was first diagnosed on the Isthmus of Panama in 1905 and has been known to be endemic since that date.
2.Approximately 117 cases of human relapsing fever were diagnosed in the Canal Zone hospitals during the twenty-six years from 1905 to 1930, inclusive.
3.Relapsing fever has been known to be endemic in Colombia, the country adjoining Panama, for a number of years.
4.Two species of Argasine ticks, Ornithodorus venezuelensis and Ornithodorus talaje, that have been proven to be transmitters of relapsing fever are prevalent in Panama and Colombia.
5.Earlier investigations on Ornithodorus venezuelensis in Colombia showed that a fairly high percentage of them were infected with spirochetes.
6.Naturally occurring spirochetal infections have been found in marmoset monkeys, opossums, armadillos, calves and a horse during the past three years in Panama.
7.In each instance the spirochetes found in these animals so closely resembled those found in human cases of relapsing fever that we believe them to be identical.
8.The infection in the monkeys was successfully transferred to man and also to white rats, white mice and various species of of monkeys.
9.The spirochetes found in the opossums were readily transferred to monkeys, white rats and white mice.
10.Inoculation experiments with clean armadillos proved them to be highly susceptible to the human strain of relapsing fever.
11.The spirochetes found in the calves were transferred to a marmoset monkey and white rats.
12.Ornithodorus talaje in the larval stage have been found infesting marmoset monkeys and opossums.
13.During recent years cases of relapsing fever have occurred from time to time in the United States. Several of these apparently acquired their infection while in isolated areas which would indicate that naturally infected mammals may be concerned in the propagation and dissemination of the disease in the United States.
14.From the literature available, we are unable to find any record of either opossums or armadillos having previously been found naturally infected with spirochetes and we believe that this indicates two new and hitherto unsuspected sources of the disease.