Prevalence of antibody to Legionella spp. in healthy Japanese

Abstract

An indirect fluorescent antibody (IFA) test was used to establish the background prevalence of antibody to Legionella spp. in a single serum specimens from healthy Japanese. These have been compared with antibody levels obtained from stocked sera and patient's sera with pneumonia or febrile illness.We used two groups of polyvalent antigens of Legionella spp., which included: group 1-L. pneumophila, serogroup 1 to 4, and group 2-L. pneumophila, serogroup 5 to 6, L. micdadei, L. bozemanii, L. dumoffii and L. longbeachae.In this paper the higher titer from group 1 and 2 was used as the titer of Legionella group. All the high titers that we observed (≥1:64) with the polyvalent antigens, was confirmed with the use of monovalent antigens.Of 527 healthy persons, 237 (45%) had titers of <4:13 (2.5%) had titers ≥1:64 (12 had a titer of 1:64 and 1 a titer of 1: 128). The proportion of antibody did not vary with sex, however, the higher age groups demonstrated greater level.The overall prevalence of seropositibity (reciprocal titer, ≥64) in 527 healthy persons, 125 patients with pneumonia or febrile illness and 755 stocked sera was in each 2.5%, 4.8% and 1.3% respectively.The observed titer of 1: 128, corresponded to L. pneumophila, serogroup 1.No serum had an antibody titer ≥1:256 in all of the 1407 sera examined.