Legionella longbeachaeand Legionellosis

Harriet Whiley,Richard Bentham

doi:10.3201/eid1704.100446

Abstract

Reported cases of legionellosis attributable to Legionella longbeachae infection have increased worldwide. In Australia and New Zealand, L. longbeachae has been a known cause of legionellosis since the late 1980s. All cases for which a source was confirmed were associated with potting mixes and composts. Unlike the situation with other Legionella spp., L. longbeachae–contaminated water systems in the built environment that cause disease have not been reported. Spatially and temporally linked outbreaks of legionellosis associated with this organism also have not been reported. Sporadic cases of disease seem to be limited to persons who have had direct contact with potting soil or compost. Long-distance travel of the organism resulting in infection has not been reported. These factors indicate emergence of an agent of legionellosis that differs in etiology from other species and possibly in route of disease transmission.

Highlights

Reported cases of legionellosis attributable to Legionella longbeachae infection have increased worldwide
The link between potting mix and legionellosis was established in 1989 when a cluster of L. longbeachae infections was detected in South Australia
The authors postulated that the discrepancy between incidence of L. longbeachae infection in Australia and the rest of the world, Europe, was attributable to the content of commercial potting mix

Summary

Introduction

Reported cases of legionellosis attributable to Legionella longbeachae infection have increased worldwide. The primary environmental reservoir of L. longbeachae remains unknown; the major source of human infection is considered to be commercial potting mixes and other decomposing materials, such as bark and sawdust (5,8,18,19). The link between potting mix and legionellosis was established in 1989 when a cluster of L. longbeachae infections was detected in South Australia. The authors postulated that the discrepancy between incidence of L. longbeachae infection in Australia and the rest of the world, Europe, was attributable to the content of commercial potting mix.

Results

Conclusion