Health risks from exposure to Legionella in reclaimed water aerosols: Toilet flushing, spray irrigation, and cooling towers

Hamilton, Kerry A.; Hamilton, Mark T.; Johnson, W. J.; Jjemba, Patrick K.; Bukhari, Zia; LeChevallier, Mark W.; Haas, Charles N.

doi:10.1016/j.watres.2017.12.022

Cited by 117 publications

(82 citation statements)

References 103 publications

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“…Therefore, legionella are widespread environmental infectious agents representing a hazard to public health. Suspected sources of legionella infections relevant to humans are, e.g., showers or cooling water reservoirs, but also dental instruments or flushing toilets that produce water aerosols [5,6].…”

Section: Introductionmentioning

confidence: 99%

Antimicrobial Effect of Visible Light—Photoinactivation of Legionella rubrilucens by Irradiation at 450, 470, and 620 nm

et al. 2019

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Despite the high number of legionella infections, there are currently no convincing preventive measures. Photoinactivation with visible light is a promising new approach and the photoinactivation sensitivity properties of planktonic Legionella rubrilucens to 450, 470, and 620 nm irradiation were thus investigated and compared to existing 405 nm inactivation data for obtaining information on responsible endogenous photosensitizers. Legionella were streaked on agar plates and irradiated with different doses by light emitting diodes (LEDs) of different visible wavelengths. When irradiating bacterial samples with blue light of 450 nm, a 5-log reduction could be achieved by applying a dose of 300 J cm−2, whereas at 470 nm, a comparable reduction required about 500 J cm−2. For red irradiation at 620 nm, no inactivation could be observed, even at 500 J cm−2. The declining photoinactivation sensitivity with an increasing wavelength is consistent with the assumption of porphyrins and flavins being among the relevant photosensitizers. These results were obtained for L. rubrilucens, but there is reason to believe that its inactivation behavior is similar to that of pathogenic legionella species. Therefore, this photoinactivation might lead to new future concepts for legionella reduction and prevention in technical applications or even on or inside the human body.

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Section: Introductionmentioning

confidence: 99%

Antimicrobial Effect of Visible Light—Photoinactivation of Legionella rubrilucens by Irradiation at 450, 470, and 620 nm

et al. 2019

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“…Wastewater is usually considered as a reservoir and vehicle for various human pathogens, and discharges into the natural environment may pose direct or indirect exposure risks. Comparing estimates from quantitative microbial risk analyses and epidemiological studies have raised public concerns regarding the health risks in wastewater irrigation [8,9]. Apart from conventional indexes related to water quality criteria, there is a need to be concerned about the microbiological quality of irrigation water in terms of its effects on the soils and crops.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Opportunistic Pathogens in Domestic Wastewater from a Pilot-Scale Anaerobic Biofilm Reactor to Reuse in Agricultural Irrigation

Cui

Liang

2019

Water

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Wastewater reuse for agricultural irrigation in many developing countries is an increasingly common practice. Regular monitoring of indicators can help to identify potential health risks; therefore, there is an urgent need to understand the presence and abundance of opportunistic pathogens in wastewater, as well as plant phyllosphere and rhizosphere. In this study, an anaerobic biofilm reactor (ABR) was developed to treat rural domestic wastewater; the performance of pollutants removal and pathogenic bacteria elimination were investigated. Additionally, we also assessed the physicochemical and microbiological profiles of soil and lettuces after wastewater irrigation. Aeromonas hydrophila, Arcobacter sp., Bacillus cereus, Bacteroides sp., Escherichia coli, Legionella sp., and Mycobacterium sp. were monitored in the irrigation water, as well as in the phyllosphere and rhizosphere of lettuces. Pathogens like B. cereus, Legionella sp. and Mycobacterium sp. were present in treated effluent with relatively high concentrations, and the levels of A. hydrophila, Arcobacter sp., and E. coli were higher in the phyllosphere. The physicochemical properties of soil and lettuce did not vary significantly. These data indicated that treated wastewater irrigation across a short time period may not alter the soil and crop properties, while the pathogens present in the wastewater may transfer to soil and plant, posing risks to human health.

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“…Most of the Legionella species detected were L. pneumophila , making up 96% of the isolates on BCYE media, and 87% of these were identified as L. pneumophila serotype 1—the strain most commonly associated with waterborne outbreaks in North America (http://www.cdc.gov/vitalsigns/legionnaires/). Hamilton et al () used the data from this study to develop several quantitative microbial risk assessment models for Legionella exposure from reclaimed water. The analysis examined nonpotable applications in which aerosols are produced (e.g., toilet flushing, spray irrigation, cooling tower blowdown) and found the risks were largely driven by the concentration of L. pneumophila in the water and the number and size of aerosol droplets.…”

Section: Discussionmentioning

confidence: 99%

“…Water used for direct or indirect potable reuse is treated to a higher standard than unrestricted reuse water and would be considered a much less significant source of Legionella spp. The study also developed a quantitative microbial risk assessment to evaluate the public health risk of L. pneumophila in various applications of unrestricted urban reuse water, but that report is published elsewhere (Hamilton et al ).…”

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confidence: 99%

Occurrence of Legionella in Nonpotable Reclaimed Water

et al. 2018

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Legionella was monitored in reclaimed water systems and were detected by culture in 50% of 115 samples, while 80% of the samples were positive by quantitative polymerase chain reaction (qPCR). The lowest level of Legionella was in a system that practiced biological nutrient removal and maintained an average 0.3 mg/L free chlorine residual. The difference between qPCR and ethidium monoazide treated samples was used as an indicator of viability, and the greatest difference was in a chloraminated system, where the molecular method indicated a 9% viability. Ninety-six percent of the species were L. pneumophila, and 87% were identified as L. pneumophila serotype 1. Total amoebae (summed as cysts or trophozoites) were detected in 100% of samples from all six systems, and were mostly (50-95%) in the active trophozoite phase. In the chloraminated system, 87% of the mesophilic amoebae and 66% of the thermophilic amoebae were in the cyst phase.

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Health risks from exposure to Legionella in reclaimed water aerosols: Toilet flushing, spray irrigation, and cooling towers

Cited by 117 publications

References 103 publications

Antimicrobial Effect of Visible Light—Photoinactivation of Legionella rubrilucens by Irradiation at 450, 470, and 620 nm

Antimicrobial Effect of Visible Light—Photoinactivation of Legionella rubrilucens by Irradiation at 450, 470, and 620 nm

Monitoring Opportunistic Pathogens in Domestic Wastewater from a Pilot-Scale Anaerobic Biofilm Reactor to Reuse in Agricultural Irrigation

Occurrence of Legionella in Nonpotable Reclaimed Water

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