Volume s1-11, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



  • 1.  We received a juvenile squirrel-monkey, (Pucheran) with a naturally acquired spirochetosis on May 20, 1930. This animal had been in captivity for a short time in the region of Arraijan and La Chorrera, Republic of Panama. This region has long been known as an endemic center for relapsing fever.
  • 2.  We secured, in August, 1930, two monkeys of this same species that were positive for a scant or latent infection of apparently the same spirochete. These animals were captured in the jungle at a point on the banks of the Tuira river above Boca de Cupe, Dárien Province, Republic of Panama. Twenty other specimens captured on the same expedition failed to show the infection. All were post mortem examinations.
  • 3.  We have passed the spirochetal infection from the squirrel-monkeys to white mice, white rats, one guinea pig, white-faced monkeys ( Thomas), red spider monkeys ( Kuhl), a night monkey ( Goldman) and to numerous squirrel-monkeys. It soon disappears from all these animals except the white rats, mice and the young squirrel-monkey, the latter being far more sensitive to the disease than even the white rats and mice.
  • 4.  The spirochete did not grow in the usual culture media employed for spirochetal study.
  • 5.  This spirochete corresponds very closely to the morphology of the various species causing relapsing fever in man.
  • 6.  Two men were given direct blood inoculations from squirrel-monkeys infected with the disease. One received a combined intradermal and subcutaneous inoculation while the other received a deep intramuscular injection. Both men developed the disease. It was passed from one man to a clean squirrel-monkey and from the other man to three other persons, one of whom failed to show spirochetes in the blood films but recovered promptly from a severe attack by the use of neoarsphenamine.
  • 7.  The squirrel-monkey spirochetosis was transferred by the the bites of 31 nymphal and adults ticks, to man. One paroxysm developed but the blood films failed to reveal spirochetes. A clean juvenile squirrel-monkey inoculated with the blood of the man on the day of his paroxysm did develop the disease promptly and died of it in about one month's time.
  • 8.  A total of 60 larval ticks, , reared from eggs deposited by females which had fed on a squirrel-monkey with the spirochetal infection from August 4 to 13, 1930, were permitted to feed on a human volunteer but the disease was not transmitted.
  • 9.  The use of this spirochete in the treatment of paresis was reported as unsatisfactory.
  • 10.  Relapse may or may not occur in the course of the disease and the interval between paroxyms may vary greatly although it is usually seven to twelve days.
  • 11.  The inoculation of a young squirrel-monkey with the blood from a case of human relapsing fever resulted in the production of symptoms and spirochetes in the blood films on the third day and the animal died in about one month's time. The course of the disease and the morphology of the spirochete was apparently the same as in the naturally acquired squirrel-monkey spirochetosis. Both strains behave as a blood stream parasite and not as a tissue spirochete.
  • 12.  There is reason to believe from the human cases in these experiments and from blood film surveys of the rural population that but few of the total cases of relapsing fever ever appear at the hospital primarily for the treatment of this disease. The usual severe hospital case probably does not represent the average case in rural communities, many of which have no severe relapses.
  • 13.  During the past year and were both found on fowls. The latter species has also been found on a number of opossums and rats. We have seen in the wild state two opossums and two armadillos with a spirochetal infection that we can not tell from that of relapsing fever. There is much to suggest that relapsing fever is primarily a disease of animals rather than of man.
  • 14.  We consider that the spirochete found in the squirrel-monkey of Panama is identical with our local species of human relapsing fever. The infant and juvenile squirrel-monkeys of Panama are the most sensative laboratory animals we can use for this form of spirochetosis. This animal, we are told, will not live long in a temperate zone climate.


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