scholarly journals Legionella pneumophila as a Health Hazard to Miners: A Pilot Study of Water Quality and QMRA

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1528
Author(s):  
Valerie Madera-García ◽  
Alexis L. Mraz ◽  
Nicolás López-Gálvez ◽  
Mark H. Weir ◽  
James Werner ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Health Hazard ◽  
Ventilation System ◽  
Sprinkler System ◽  
Dust Control ◽  
Quantitative Microbial Risk Assessment ◽  
Mining Operations ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Life Years

Legionella pneumophila (L. pneumophila), the causative agent of legionellosis, is an aquatic bacterium that grows in warm water. Humans are only presented with a health risk when aerosolized water containing L. pneumophila is inhaled. In mining operations, aerosolized water is used as dust control and as part of the drilling operations, a currently ignored exposure route. This study characterized L. pneumophila concentrations in the mine’s non-potable water and the relationship between L. pneumophila and chlorine concentrations. These concentrations informed a quantitative microbial risk assessment (QMRA) model to estimate the infection risk to miners exposed to aerosolized water containing L. pneumophila. Fourteen water samples were collected from seven locations at a mine and analyzed for temperature, pH, chlorine, and L. pneumophila serogroup. Most samples (93%) tested positive for L. pneumophila cells. The faucet from the sprinkler system on the adit level (entrance to the underground mine levels) showed the highest concentration of L. pneumophila (8.35 × 104 MPN/L). Disability adjusted life years (DALYs) were estimated in the QMRA model and showed that the risk for all miners was significantly lower (p < 0.0001) with the ventilation system on than when the system was off. Our study showed that the use of a ventilation system at the adit level of the mine reduced the risk of infection with aerosolized L. pneumophila.

scholarly journals Quantification of the health risk associated with wastewater reuse in Accra, Ghana: a contribution toward local guidelines

2008 ◽  
Vol 6 (4) ◽  
pp. 461-471 ◽  
Author(s):  
Razak Seidu ◽  
Arve Heistad ◽  
Philip Amoah ◽  
Pay Drechsel ◽  
Petter D. Jenssen ◽  
...  
Keyword(s):  
Irrigation Water ◽  
Health Hazard ◽  
Wastewater Reuse ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Post Harvest ◽  
Pipe Water ◽  
Tolerable Risk ◽  
Rotavirus Infections

Quantitative Microbial Risk Assessment (QMRA) models with 10,000 Monte Carlo simulations were applied to ascertain the risks of rotavirus and Ascaris infections for farmers using different irrigation water qualities and consumers of lettuce irrigated with the different water qualities after allowing post-harvest handling. A tolerable risk (TR) of infection of 7.7 × 10−4 and 1 × 10−2 per person per year were used for rotavirus and Ascaris respectively. The risk of Ascaris infection was within a magnitude of 10−2 for farmers accidentally ingesting drain or stream irrigation water; ∼100 for farmers accidentally ingesting farm soil and 100 for farmers ingesting any of the irrigation waters and contaminated soil. There was a very low risk (10−5) of Ascaris infection for farmers using pipe−water. For consumers, the annual risks of Ascaris and rotavirus infections were 100 and 10−3 for drain and stream irrigated lettuce respectively with slight increases for rotavirus infections along the post-harvest handling chain. Pipe irrigated lettuce recorded a rotavirus infection of 10−4 with no changes due to post harvest handling. The assessment identified on-farm soil contamination as the most significant health hazard.

scholarly journals Quantitative Microbial Risk Analysis to evaluate health effects of interventions in the urban water system of Accra, Ghana

2010 ◽  
Vol 8 (3) ◽  
pp. 417-430 ◽  
Author(s):  
Herve Labite ◽  
Isabella Lunani ◽  
Peter van der Steen ◽  
Kala Vairavamoorthy ◽  
Pay Drechsel ◽  
...  
Keyword(s):  
Disease Burden ◽  
Water System ◽  
Reference Value ◽  
Urban Water ◽  
Quantitative Microbial Risk Assessment ◽  
Indicator Organisms ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Urban Water System ◽  
Life Years

A quantitative microbial risk assessment was applied to evaluate the microbial risks of the Accra Urban Water System (AUWS). The exposure assessment was based on the count of indicator organisms in waste water from open roadside drains and in water and sand samples from the beach. The predicted total disease burden generated in a representative catchment of the AUWS (Odaw Catchment) was 36,329 Disability Adjusted Life Years (DALYs) per year, of which 12 and 88% are caused by, respectively, shortcomings in the water supply system and inappropriate sanitation. The DALYs per person per year were above the WHO reference value. The open roadside drain had the highest contribution to the disease burden. Of four possible interventions evaluated for health risk reduction, the highest efficiency in terms of DALYs averted per euro invested would be achieved by providing covers for the open roadside drains.

scholarly journals An Advanced Risk Modeling Method to Estimate Legionellosis Risks Within a Diverse Population

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 43
Author(s):  
Mark H. Weir ◽  
Alexis L. Mraz ◽  
Jade Mitchell
Keyword(s):  
Legionella Pneumophila ◽  
Accurate Method ◽  
Incidence Rates ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Modeling ◽  
Microbial Risk Assessment ◽  
Homogeneity Assumption ◽  
Life Years ◽  
Significant Difference ◽  
Legionnaires Disease

Quantitative microbial risk assessment (QMRA) is a computational science leveraged to optimize infectious disease controls at both population and individual levels. Often, diverse populations will have different health risks based on a population’s susceptibility or outcome severity due to heterogeneity within the host. Unfortunately, due to a host homogeneity assumption in the microbial dose-response models’ derivation, the current QMRA method of modeling exposure volume heterogeneity is not an accurate method for pathogens such as Legionella pneumophila. Therefore, a new method to model within-group heterogeneity is needed. The method developed in this research uses USA national incidence rates from the Centers for Disease Control and Prevention (CDC) to calculate proxies for the morbidity ratio that are descriptive of the within-group variability. From these proxies, an example QMRA model is developed to demonstrate their use. This method makes the QMRA results more representative of clinical outcomes and increases population-specific precision. Further, the risks estimated demonstrate a significant difference between demographic groups known to have heterogeneous health outcomes after infection. The method both improves fidelity to the real health impacts resulting from L. pneumophila infection and allows for the estimation of severe disability-adjusted life years (DALYs) for Legionnaires’ disease, moderate DALYs for Pontiac fever, and post-acute DALYs for sequela after recovering from Legionnaires’ disease.

scholarly journals Flushing of stagnant premise water systems after the COVID-19 shutdown can reduce infection risk by Legionella and Mycobacterium spp.

2020 ◽  
Author(s):  
Raymond M Hozalski ◽  
Timothy M LaPara ◽  
Xiaotian Zhao ◽  
Taegyu Kim ◽  
Michael B Waak ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Levels ◽  
Hot Water ◽  
Quantitative Microbial Risk Assessment ◽  
Opportunistic Pathogens ◽  
Bacterial Gene ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Commercial Cultivation ◽  
Premise Plumbing

The unprecedented widespread closing of buildings due to the COVID-19 pandemic has allowed water to stagnate in premise plumbing systems, creating conditions that may facilitate the growth of opportunistic pathogens. In this study, we flushed and collected samples from showers in buildings that had been unoccupied for approximately two months and quantified Legionella pneumophila using a commercial cultivation-based assay. In addition, all bacteria, Legionella spp., L. pneumophila, L. pneumophila serogroup 1, non-tuberculous mycobacteria (NTM), and Mycobacterium avium complex (MAC) were analyzed using quantitative PCR (qPCR). Despite low or negligible total chlorine in the stagnant pre-flush water samples, L. pneumophila were not detected by either method; Legionella spp., NTM, and MAC, however, were widespread. Using quantitative microbial risk assessment (QMRA), estimated risks of clinical illness from exposure to legionella and MAC via showering were generally low, but the risk of subclinical infection via Legionella spp. could exceed a 10-7 daily risk threshold if just a small fraction (≥0.1 %) of those legionellae detected by qPCR are highly infectious. Flushing cold and hot water lines rapidly restored a total chlorine (as chloramine) residual and decreased all bacterial gene targets to building inlet water levels within 30 min. Following flushing, the chlorine residual rapidly dissipated and bacterial gene targets rebounded, approaching pre-flush concentrations after 6 to 7 days of stagnation. These results suggest that stagnant water in premise plumbing may contain elevated levels of opportunistic pathogens; flushing, however, can rapidly improve water quality and reduce the health risk but the improvement will be short-lived if building disuse persists.

scholarly journals Direct and indirect QMRA of infectious Cryptosporidium oocysts in reclaimed water

2012 ◽  
Vol 10 (4) ◽  
pp. 539-548 ◽  
Author(s):  
M. Agulló-Barceló ◽  
R. Casas-Mangas ◽  
F. Lucena
Keyword(s):  
Uv Light ◽  
Health Hazard ◽  
Reclaimed Water ◽  
Poisson Model ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Treatment Type ◽  
Cryptosporidium Oocysts ◽  
The Mean

Water scarcity leads to an increased use of reclaimed water, which in turn calls for an improvement in water reclamation procedures to ensure adequate quality of the final effluent. The presence of infectious Cryptosporidium oocysts (IOO) in reclaimed water is a health hazard for users of this resource. Here, we gathered information on Cryptosporidium (concentrations, infectivity and genotype) in order to perform quantitative microbial risk assessment (QMRA). Moreover, data concerning the spores of sulphite-reducing clostridia (SRC) were used to undertake QMRA at a screening level. Our results show that the probability of infection (PI) by Cryptosporidium depends on the tertiary treatment type. The mean PI using the exponential dose-response model was 3.69 × 10−6 in tertiary effluents (TE) treated with UV light, whereas it was 3 log10 units higher, 1.89 × 10−3, in TE not treated with this disinfection method. With the β-Poisson model, the mean PI was 1.56 × 10−4 in UV-treated TE and 2 log10 units higher, 4.37 × 10−2, in TE not treated with UV. The use of SRC to perform QMRA of Cryptosporidium showed higher PI than when using directly IOO data. This observation suggests the former technique is a conservative method of QMRA.

Enteric virus presence in green vegetables and associated irrigation waters in a rural area from Argentina. A quantitative microbial risk assessment

LWT ◽  
2021 ◽  
Vol 144 ◽  
pp. 111201 ◽  
Author(s):  
Prez Verónica Emilse ◽  
Victoria Matías ◽  
Martínez Laura Cecilia ◽  
Giordano Miguel Oscar ◽  
Masachessi Gisela ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Rural Area ◽  
Enteric Virus ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Irrigation Waters
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