Alternative Routes for Dissemination of Legionella pneumophila Causing Three Outbreaks in Norway

Abstract

Three outbreaks of Legionnaires' disease were reported in the Fredrikstad/Sarpsborg community, Norway, in 2005 and 2008 caused by the L. pneumophila ST15 and ST462 strains determined by sequence based typing. In this retrospective study, we suggest that the aeration ponds, a part of the biological treatment plant at Borregaard Ind. Ltd., are the main amplifiers and primary disseminators of the outbreak L. pneumophila strains. This result is supported by the finding that the ST15 and ST462 strains were not able to survive in air scrubber liquid media more than two days of incubation at the scrubber's operating conditions during the 2005 and 2008 outbreaks. In 2008, >10¹⁰ CFU/L of L. pneumophila ST462 were detected in the aeration ponds. ST15 and ST462 were also detected in the river Glomma in 2005 and 2008, respectively, downstream of the wastewater outlet from the treatment plant (10⁵CFU/L). These findings strongly suggest that the presence of L. pneumophila in the river is due to the release of wastewater from the industrial aeration ponds, demonstrating that the river Glomma may be an additional disseminator of L. pneumophila during the outbreaks. This work emphasizes the need for preventive actions against the release of wastewater containing human pathogens to the environment.

High-Throughput Typing Method To Identify a Non-Outbreak-Involved Legionella pneumophila Strain Colonizing the Entire Water Supply System in the Town of Rennes, France

“…The current typing method recommended by the European EWGLI Consortium is a multilocus sequence typing (MLST)-like protocol called sequence-based typing (SBT) (18,30). This approach is highly portable and widely used to perform epidemiological surveys and outbreak inves-tigation (27) owing to the existence of databases accessible over the internet. However, SBT remains tedious and timeconsuming, as it requires the sequencing of both strands of seven gene fragments.…”

Legionellaand non-Legionellabacteria in a biological treatment plant

“…The aeration ponds of the biological treatment plant at the wood and pulp factory Borregaard Ind. Ltd., a world's leading supplier of lignin-based chemicals, were identified as the main amplifiers and primary disseminators of the outbreak strain of L. pneumophila (Olsen et al 2010). Legionella pneumophila was measured at concentration levels up to 3300 CFU/L in air samples taken directly above the aeration ponds and at lower levels up to 200 m downwind from the ponds (Blatny et al 2008).…”

On the Use of Computational Fluid Dynamics to Investigate Aerosol Dispersion in an Industrial Environment: A Case Study

“…Liquid samples taken directly from these aeration ponds (Blatny et al 2008(Blatny et al , 2011, and samples of aerosols collected immediately above the liquid surfaces (Olsen et al 2010), have all revealed the presence of the microorganism Legionella spp. Blatny et al (2008) proved that Legionella-containing aerosols could be dispersed from the aeration ponds and transported at least 300 m downwind of the ponds.…”

“…Ltd., Norway (cf. Blatny et al 2008Blatny et al , 2011Olsen et al 2010). The aeration ponds considered in this study have been identified as two of several possible sources responsible for the outbreak in 2005.…”