A review of Legionella pneumophila in horses and some South African serological results.

An examination of the sera of 329 horses for L. pneumophila antibodies revealed a much lower exposure rate than that reported in the United States of America. Further serological investigations of persons closely associated with a sero-positive horse indicated that the horse could not be considered to be a source of infection but that both humans and animals were probably exposed to a common source of infection. The results showed that 192/329 (58.4%) of the sera tested negative, 114/329 (34.7%) had end-point titres of 1/2, 22/329 (6.7%) end-points of 1/16 and one an end point of 1/256 (0.3%). Serological testing of the people closely associated with horses showed that out of 22 people, 3 had a positive end-point titre of 1:64 and only one person showed an end-point titre of 1:256.