he strain was isolated in the Panama Canal Zone from a Spiny rat (Proechimys semispinosus) by Gale and typed by alton (WHO, 1976).
It was included in the list of 1967 (WHO, 1967) under provisional status under the name proechimys, with reference strain LT 796. Its separate serovar status has been confirmed by Manev (1976), using factor analysis (Manev, 1976). Only in the publication of 1982 by Sulzer et al. are further details given including the name of the reference strain as 1161 U, which had to replace the former laboratory code LT 796.