Two hundred and ninety-four specimens of aqueous humor and cerebrospinal fluid from 34 chimpanzees were examined for treponeme-like forms with a direct fluorescent antibody technique. One such form was found in 44 specimens from eight animals having a reactive fluorescent treponemal antibody-absorption (FTA-ABS) test prior to experimental infection, one in 170 specimens from six animals having untreated experimental syphilis of two to three years' duration, and one in 14 specimens of aqueous humor from six animals having pinta of one to two years' duration. None was seen in 49 specimens from animals with non-reactive FTA-ABS tests prior to experimental infection, or in 18 specimens from eight animals examined three to four years following penicillin treatment for experimental syphilis. Seven percent of the fluids examined contained "suspicious" forms which could not definitely be classified as treponemes.
Elsas FJ, Cox PM, Bullard JC, Kuhn USG, Chandler FW. Treponeme-like Forms in Chimpanzee Aqueous Humor and Cerebrospinal Fluid. Arch Ophthalmol. 1972;87(3):333-336. doi:10.1001/archopht.1972.01000020335019