A survey of domestic animals to detect serological responses against Legionella spp. by indirect fluorescent antibody.

One hundred ninety-six (196) animal sera were examined for antibodies against heat-killed antigens of Legionella pneumophila serogroups 1 to 5, L. bozemanii, L. dumoffii, L. gormanii and L. micdadei by the indirect fluorescent antibody technique. Only two animals (1%), both sheep, reacted against L. pneumophila serogroups at a titer of 256. However, 29% of the horses and 24% of the sheep tested were reactive to at least one non-L. pneumophila Legionella spp. antigen at a titer of 256. At a titer of 128, 72% of the pigs, 56% of the sheep and 50% of the horses were reactive to at least one Legionella spp. antigen. Despite the presence of high antibody titers against Legionella antigens, conclusive evidence of infection by these agents in animals is dependent upon further studies.