Legionella is an opportunistic waterborne pathogen that causes Legionnaires\' disease. It poses a significant public health risk, especially to vulnerable populations in health care facilities. It is ubiquitous in manufactured water systems and is transmitted via inhalation or aspiration of aerosols/water droplets generated from water fixtures (e.g., showers and hand basins). As such, the effective management of premise plumbing systems (building water systems) in health care facilities is essential for reducing the risk of Legionnaires\' disease. Chemical disinfection is a commonly used control method and chlorine-based disinfectants, including chlorine, chloramine, and chlorine dioxide, have been used for over a century. However, the effectiveness of these disinfectants in premise plumbing systems is affected by various interconnected factors that can make it challenging to maintain effective disinfection. This systematic literature review identifies all studies that have examined the factors impacting the efficacy and decay of chlorine-based disinfectant within premise plumbing systems. A total of 117 field and laboratory-based studies were identified and included in this review. A total of 20 studies directly compared the effectiveness of the different chlorine-based disinfectants. The findings from these studies ranked the typical effectiveness as follows: chloramine > chlorine dioxide > chlorine. A total of 26 factors were identified across 117 studies as influencing the efficacy and decay of disinfectants in premise plumbing systems. These factors were sorted into categories of operational factors that are changed by the operation of water devices and fixtures (such as stagnation, temperature, water velocity), evolving factors which are changed in-directly (such as disinfectant concentration, Legionella disinfectant resistance, Legionella growth, season, biofilm and microbe, protozoa, nitrification, total organic carbon(TOC), pH, dissolved oxygen(DO), hardness, ammonia, and sediment and pipe deposit) and stable factors that are not often changed(such as disinfectant type, pipe material, pipe size, pipe age, water recirculating, softener, corrosion inhibitor, automatic sensor tap, building floor, and construction activity). A factor-effect map of each of these factors and whether they have a positive or negative association with disinfection efficacy against Legionella in premise plumbing systems is presented. It was also found that evaluating the effectiveness of chlorine disinfection as a water risk management strategy is further complicated by varying disinfection resistance of Legionella species and the form of Legionella (culturable/viable but non culturable, free living/biofilm associated, intracellular replication within amoeba hosts). Future research is needed that utilises sensors and other approaches to measure these key factors (such as pH, temperature, stagnation, water age and disinfection residual) in real time throughout premise plumbing systems. This information will support the development of improved models to predict disinfection within premise plumbing systems. The findings from this study will inform the use of chlorine-based disinfection within premise plumbing systems to reduce the risk of Legionnaires disease.

This study was conducted to investigate the effects of heated water intake on the growth performance, serum biochemical indexes, apparent total tract digestibility (ATTD) of nutrients and ruminal fermentation function of yak calves in winter. A total of 24 yaks (59.09 ± 3.181 kg) were randomly selected and divided into a cold water (fluctuated with the temperature of test sites at 0-10 °C) group (CW) (58.58 ± 3.592 kg) and a heated water (20 °C) group (HW) (59.61 ± 2.772 kg). After 2 months of the experiment, body weight, serum biochemical indexes, ruminal fermentation characteristics and ATTD were measured. The results showed that drinking heated water increased (p < 0.05) the total weight gain and average daily gain of yaks compared with those drinking cold water. Heated water increased (p < 0.05) the levels of immune globulin M, interleukin-6, triiodothyronine, tetraiodothyronine and growth hormone compared with cold water. In addition, yaks drinking heated water showed higher (p < 0.05) ATTD of crude protein and ether extract, as well as increased (p < 0.05) content of total protein, albumin and urea nitrogen in serum than those drinking cold water. Compared with cold water, heated water showed increased (p < 0.05) total volatile fatty acids, acetic acid and propionic acid, and a reduced (p < 0.05) acetic acid to propionic acid ratio (p < 0.05). In conclusion, drinking heated water at 20 °C could improve performance via increasing nutrient digestibility and ruminal fermentation function in yak calves.

Thermal treatment has become the most used delousing method in salmonid aquaculture. However, concerns have been raised about it being painful for the fish. We studied the behavioural response of Atlantic salmon acclimated to 8 °C when transferred to temperatures in the range 0-38 °C. Exposure time was 5 min or until they reached the endpoint of losing equilibrium and laying on their side, a sign of imminent death. At temperatures below 28 °C, none of the fish reached endpoint within the 5-min maximum. At 28 °C four of five fish reached endpoint, and fish reached endpoint more rapidly as temperature increased further. Fish transferred to temperatures above 28 °C had higher swimming speed immediately after transfer and maintained a high swimming speed until just before loss of equilibrium. Their behaviour was from the start characterised by collisions into tank walls and head shaking. Just before loss of equilibrium they started breaking the surface of the water, swimming in a circle pattern and in some instances displayed a side-wise bending of their body. In other words, salmon transferred to temperatures above 28 °C showed instant behavioural responses indicative of nociception or pain.

Slow sand filtration with extensive pretreatment reduces the microbial growth potential of drinking water to a minimum level at four surface water supplies in The Netherlands. The potential of these slow sand filtrates (SSFs) to promote microbial growth in warm tap water installations was assessed by measuring biofilm formation and growth of Legionella bacteria on glass and chlorinated polyvinylchloride (CPVC) surfaces exposed to SSFs at 37 ± 2°C in a model system for up to six months. The steady-state biofilm concentration ranged from 230 to 3,980 pg ATP cm-2 on glass and 1.4 (±0.3)-times-higher levels on CPVC. These concentrations correlated significantly with the assimilable organic carbon (AOC) concentrations of the warm water (8 to 24 µg acetate-C equivalents [ac-C eq] liter-1), which were raised about 2 times by mixing cold and heated (70°C) SSFs. All biofilms supported growth of Legionella pneumophila with maximum concentrations ranging from 6 × 102 to 1.5 × 105 CFU cm-2 Biofilms after ≤50 days of exposure were predominated by Betaproteobacteriales, mainly Piscinibacter, Caldimonas, Methyloversatilis, and an uncultured Rhodocyclaceae bacterium. These rapidly growing primary colonizers most likely served as prey for the host amoebae of L. pneumophila Alphaproteobacteria, mostly Xanthobacteraceae, e.g., Bradyrhizobium, Pseudorhodoplanes, and other amoeba-resistant bacteria, accounted for 37.5% of the clones retrieved. A conceptual model based on a quadratic relationship between the L. pneumophila colony count and the biofilm concentration under steady-state conditions is used to explain the variations in the Legionella CFU pg-1 ATP ratios in the biofilms.IMPORTANCE Proliferation of L. pneumophila in premise plumbing poses a public health threat. Extended water treatment using physicochemical and biofiltration processes, including slow sand filtration, at four surface water supplies in The Netherlands reduces the microbial growth potential of the treated water to a minimum level, and the distributed drinking water complies with high quality standards. However, heating of the water in warm tap water installations increases the concentration of easily assimilable organic compounds, thereby promoting biofilm formation and growth of L. pneumophila Prevention of biofilm formation in plumbing systems by maintenance of a disinfectant residual during distribution and/or further natural organic matter (NOM) removal is not feasible in the supplies studied. Temperature management in combination with optimized hydraulics and material selection are therefore essential to prevent growth of L. pneumophila in premise plumbing systems. Still, reducing the concentration of biodegradable compounds in drinking water by appropriate water treatment is important for limiting the Legionella growth potential.

BACKGROUND: Regular exercise is an effective intervention to decrease blood pressure (BP) in hypertension, but no data are available concerning the effects of heated water-based exercise (HEx). This study examines the effects of HEx on BP in resistant hypertensive patients.
METHODS: This is a parallel, randomized controlled trial. 125 nonconsecutive sedentary patients with resistant hypertension from a hypertension outpatient clinic in a university hospital were screened; 32 patients fulfilled the study requirements. The training was performed for 60-minute sessions in a heated pool (32°C), three times a week for 12 weeks. The HEx protocol consisted of callisthenic exercises and walking inside the pool. The control group was asked to maintain habitual activities. The main outcome measure was change in mean 24-hour ambulatory BP (ABPM).
RESULTS: 32 patients (HEx n=16; control n=16) were randomized; none were lost to follow-up. Office BPs decreased significantly after heated water exercise (36/12 mmHg). HEx decreased 24-hour systolic (from 137±23 to 120±12 mmHg, p=0.001) and diastolic BPs (from 81±13 to 72±10 mmHg, p=0.009); daytime systolic (from 141±24 to 120±13 mmHg, p<0.0001) and diastolic BPs (from 84±14 to 73±11 mmHg, p=0.003); and nighttime systolic (from 129±22 to 114±12 mmHg, p=0.006) and diastolic BPs (from 74±11 to 66±10 mmHg, p<0.0001). The control group after 12 weeks significantly increased in 24-hour systolic and diastolic BPs, and daytime and nighttime diastolic BPs.
CONCLUSIONS: HEx reduced office BPs and 24-hour ABPM levels in resistant hypertensive patients. These effects suggest that HEx may be a potential new therapeutic approach in these patients.