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Exposition aux bioaérosols dans les centres de traitement des eaux usées Application d'approches moléculaires et risque viral
Abstract
Le traitement des eaux usées comporte plusieurs étapes susceptibles de générer des
bioaérosols auxquels des travailleurs peuvent être exposés. Bien que la littérature à ce sujet soit relativement abondante, les connaissances relatives au risque, à l’exposition et à la fréquence de certaines maladies chez cette population demeurent mal documentées.
L’environnement des centres de traitement des eaux usées est complexe à plusieurs égards. En effet, les différents sites de traitement représentent des risques variables en ce qui a trait à la nature et à la concentration des bioaérosols, ainsi qu’au type de travail effectué. La majorité des études s’intéressant à cette problématique ont utilisé des approches dites classiques, utilisant la culture de microorganismes, afin d’étudier la concentration et la nature des bioaérosols. Très peu de données relatives à certaines infections virales (grippe, gastroentérite) sont disponibles, rendant difficile l’évaluation du risque associé à ce type de travail.
Les pays nordiques représentent une situation particulière, car les saisons ont un impact sur différents paramètres comme le confinement intérieur des étapes de traitement, les débits de ventilation des établissements et la variation de la température de l’eau à traiter. La compréhension de l’influence des saisons sur l’exposition professionnelle est donc importante. Très peu d’informations sont disponibles quant à l’incidence des symptômes respiratoires et gastroentériques chez les travailleurs oeuvrant dans ce milieu, symptômes pour lesquels les travailleurs s’absentent du travail. Cette recherche vise à combler certaines lacunes dans les connaissances relatives au risque professionnel associé au travail dans les centres de traitement des eaux usées (CTEU), tout en mettant à profit une expertise unique dans l’analyse des bioaérosols (bactériens et viraux) et en appliquant des technologies modernes de biologie moléculaire. Grâce à ces technologies, il devient possible de mieux décrire l’exposition des travailleurs de ce secteur d’activité à certains virus pathogènes respiratoires ou gastro-intestinaux.
Ce projet de recherche a permis de décrire la diversité des bioaérosols et de documenter des corrélations inattendues entre les bactéries cultivables et les endotoxines, suggérant un abaissement d’exposition aux bactéries cultivables. La biologie moléculaire a permis de mesurer de façon efficace les bactéries totales dans les bioaérosols et cette mesure est suggéré comme marqueur d’exposition potentiel. La présence de nombreux virus par
biologie moléculaire a aussi été démontrée, mais leur degré d’infectivité n’a pas été établi.
Seul l’adénovirus montre une corrélation avec les bactéries totales estimées et les
endotoxines. La mesure de ce virus pourrait servir de biomarqueur d’exposition. Des
échantillonnages personnels ont validé les niveaux d’exposition aux bioaérosols. Enfin, des questionnaires longitudinaux autoadministrés proposent que les travailleurs des CTEU sont plus fréquemment victimes de symptômes gastroentériques, qu’ils s’absentent plus fréquemment du travail pour cette raison et qu’ils sont plus sujets à ressentir des symptômes relatifs au contact avec de l’air de moins bonne qualité. Cette étude d’envergure a permis une caractérisation exhaustive de l’exposition aux bioaérosols infectieux, non infectieux et sensibilisants, ce qui contribuera éventuellement à une meilleure évaluation du risque et à l’implantation de mesures visant à mieux contrôler l’exposition. Aussi, l’étude pilote effectuée auprès d’un sous-groupe de travailleurs de ce milieu a permis d’approfondir l’incidence de symptômes respiratoires et gastroentériques au sein de cette population.
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Bioaerosol studies aim to describe the microbial content and increase understanding of the aerosolization processes linked to diseases. Air samplers are used to collect, identify, and quantify bioaerosols. Studies comparing the performances of air samplers have typically used a culture approach or have targeted a specific microorganism in laboratory settings. The objective of this study was to use environmental field samples to compare the efficiencies of 3 high-airflow-rate samplers for describing bioaerosol diversity using a next-generation sequencing approach. Two liquid cyclonic impactors and one electrostatic filter dry sampler were used in four wastewater treatment plants to target bacterial diversity and in five dairy farms to target fungal diversity. The dry electrostatic sampler was consistently more powerful in collecting more fungal and bacterial operational taxonomic units (OTUs). Substantial differences in OTU abundances between liquid and dry sampling were revealed. The majority of the diversity revealed by dry electrostatic sampling was not identified using the cyclonic liquid impactors. The findings from this work suggest that the choice of a bioaerosol sampler should include information about the efficiency and ability of samplers to cover microbial diversity. Although these results suggest that electrostatic filters result in better coverage of the microbial diversity among the tested air samplers, further studies are needed to confirm this hypothesis. While it is difficult to determine a single universally optimal air sampler, this work provides an in-depth look at some of the considerations that are essential when choosing an air sampler for studying the microbial ecology of bioaerosols.
Functional gastrointestinal disorders (FGIDs) account for at least 40% of all referrals to gastroenterologists. Of the 33 recognized adult FGIDs, irritable bowel syndrome (IBS) is the most prevalent, with a worldwide prevalence estimated at 12%. IBS is an important health care concern as it greatly affects patients' quality of life and imposes a significant economic burden to the health care system. Cardinal symptoms of IBS include abdominal pain and altered bowel habits. The absence of abdominal pain makes the diagnosis of IBS untenable. The diagnosis of IBS can be made by performing a careful review of the patient's symptoms, taking a thoughtful history (e.g., diet, medication, medical, surgical, and psychological history), evaluating the patient for the presence of warning signs (e.g., "red flags" of anemia, hematochezia, unintentional weight loss, or a family history of colorectal cancer or inflammatory bowel disease), performing a guided physical examination, and using the Rome IV criteria. The Rome criteria were developed by a panel of international experts in the field of functional gastrointestinal disorders. Although initially developed to guide researchers, these criteria have undergone several revisions with the intent of making them clinically useful and relevant. This monograph provides a brief overview on the development of the Rome criteria, discusses the utility of the Rome IV criteria, and reviews how the criteria can be applied clinically to diagnose IBS. In addition, a diagnostic strategy for the cost-effective diagnosis of IBS will be reviewed.
The use of aerosolized bacteriophages as surrogates to hazardous viruses could simplify and accelerate the discovery of links between viral components and their persistence in the airborne state under diverse environmental conditions. In this study, four structurally distinct lytic phages, MS2 (ssRNA), Φ6 (dsRNA), ΦX174 (ssDNA) and PR772 (dsDNA), were nebulised into a rotating chamber and exposed to various levels of relative humidity (RH) and temperature as well as to germicidal ultraviolet radiations. The aerosolized viral particles were allowed to remain airborne for up to fourteen hours before being sampled for analysis by plaque assays and quantitative PCR. Phages Φ6 and MS2 were most resistant at low levels of relative humidity whilst ΦX174 was more resistant at 80% RH. Phage Φ6 lost its infectivity immediately after exposure to 30°C and 80% RH. The infectivity of all tested phages rapidly declined as a function of the exposure time to UV-C radiations, phage MS2 being the most resistant. Taken altogether, our data indicate that these aerosolized phages behave differently under various environmental conditions and highlight the necessity of carefully selecting viral simulants in bioaerosols studies.
Copyright © 2015, American Society for Microbiology. All Rights Reserved.
The term 'unculturable' is used to describe bacteria that are not grown on artificial media till date and thus these are referred as unculturables. We do not have sufficient biological information to culture these bacteria in vitro. These microscopic cells are considered to be dead and therefore would never grow posed the anomaly without classifying them. In fact, many of these cells were shown to be metabolically active, even though they were not able to grow on laboratory media.
Detection of hepatitis viral infections has traditionally relied on the circulating antibody test using the enzyme-linked immunosorbent assay. However, multiplex real-time PCR has been increasingly used for a variety of viral nucleic acid detections and has proven to be superior to traditional methods. Hepatitis A virus (HAV) and hepatitis E virus (HEV) are the major causes of acute hepatitis worldwide; both HAV and HEV infection are a main public health problem. In the present study, a one-step multiplex reverse transcriptase quantitative polymerase chain reaction assay using hydrolysis probes was developed for simultaneously detecting HAV and HEV. This novel detection system proved specific to the target viruses, to be highly sensitive and to be applicable to clinical sera samples, making it useful for rapid, accurate and feasible identification of HAV and HEV.
Highly pathogenic avian influenza A/H5N1 virus can cause morbidity and mortality in humans but thus far has not acquired the ability to be transmitted by aerosol or respiratory droplet ("airborne transmission") between humans. To address the concern that the virus could acquire this ability under natural conditions, we genetically modified A/H5N1 virus by site-directed mutagenesis and subsequent serial passage in ferrets. The genetically modified A/H5N1 virus acquired mutations during passage in ferrets, ultimately becoming airborne transmissible in ferrets. None of the recipient ferrets died after airborne infection with the mutant A/H5N1 viruses. Four amino acid substitutions in the host receptor-binding protein hemagglutinin, and one in the polymerase complex protein basic polymerase 2, were consistently present in airborne-transmitted viruses. The transmissible viruses were sensitive to the antiviral drug oseltamivir and reacted well with antisera raised against H5 influenza vaccine strains. Thus, avian A/H5N1 influenza viruses can acquire the capacity for airborne transmission between mammals without recombination in an intermediate host and therefore constitute a risk for human pandemic influenza.
Although bioaerosols from both cage-housed (CH) and floor-housed (FH) poultry operations are highly concentrated, the concentrations of dust, endotoxin, and bacteria are significantly higher in FH bioaerosols. Workers from CH operations have reported a greater prevalence of respiratory symptoms. To date, archaea have been examined in swine and dairy bioaerosols but not in poultry bioaerosols. The objective of this study was to directly compare methanogenic archaea concentrations in bioaerosols from CH and FH poultry facilities. Bioaerosols were collected from 15 CH and 15 FH poultry operations, using stationary area samplers as well as personal sampling devices. Archaea were quantified and their diversity was investigated using polymerase chain reaction (PCR) followed by denaturing gradient gel electrophoresis (DGGE) and band sequencing. Archaea were significantly higher in area and personal bioaerosols of CH poultry operations than in those from FH poultry operations (p < 0.001 and p < 0.05, respectively) and did not differ significantly between area and personal samples within each barn type. Sequences matching Methanobrevibacter woesei, an archaea previously found in poultry samples, were detected in bioaerosol samples from CH operations. Methanogenic archaea concentrations are significantly different between bioaerosols from CH and FH poultry operations.
Raw sewage contains various pathogenic organisms including bacteria, viruses, fungus, worms and protozoa. Workers at wastewater treatment plants (WWTPs) are exposed to these organisms as well as to H2S gas causing many health hazards.
To assess some work-related health effects among WWTPs workers with special emphasis on the most common infections as well as cardiopulmonary disorders.
43 workers at Berket Al-Sabih WWTPs were studied. An equal number of non-exposed comparison group were also studied. All participants were asked about their personal demographic data, symptoms suggesting infection, respiratory tract impairment and cardiovascular manifestations. Spirometric measurements were made at the end of the work shift. A resting standard 12-lead ECG was also taken for each participant. For those with a positive ECG finding, echocardiography was also performed. Serum examination for antibodies against hepatitis A virus (HAV) and hepatitis E virus (HEV) was also done. A heparinized blood sample to measure sulf-hemoglobin, as an indicator of H2S exposure, was taken. Stool was analyzed by polymerase chain reaction (PCR) for Leptospira spirochete.
WWTPs workers suffered from body ache, abdominal pain, wheeze, asthma and dyspnea more frequently than the comparison group (p<0.05). An obstructive pattern of pulmonary function impairment and a higher mean sulf-hemoglobin% were significantly more common among WWTPs workers than the comparison group. Antibody levels against HAV and HEV as well as frequency of positive stool PCR test results for L. spirochete were significantly higher among WWTPs workers than the comparison group. The prevalence of left ventricular hypertrophy (LVH) according to ECG and mean ejection fraction (EF) as measured by echocardiography were significantly more frequent in WWTPs workers than in the comparison group.
WWTPs workers are high risk of developing various infections and cardiopulmonary diseases.
Using miniature perfluorocarbon tracer (PFT) sources and miniature passive samplers, both about the size of a cigarette, tests conducted in the laboratory and in a typical home successfully demonstrated the utility of the PFT kit as a means for implementing wide-scale infiltration measurements in homes. The PFT diffusion plug source, an elastomer containing a dissolved perfluorocarbon compound, was shown to emit vapors at the rate of about 0.1 to 5 nL/min, providing steady-state concentrations in a home of about 1 to 10 pL/L, i.e., parts per trillion by volume, when one source is deployed for each 300–500 ft2 (28–46 m2) of living space. The emission rate from the diffusion source was predictable, but its dependence on both temperature and time suggested the development of alternative approaches. One such alternative, a liquid PFT permeation source, had emission rates which could be tailored over the range 10–20 nL/min, were independent of age for as long as the liquid remained (∼ 5 yr), and had significantly lower temperature dependence. A number of passive adsorption tube samplers performed reproducibly and identically (to within ±2%–3%) in laboratory tests. Together with a programmable tracer sampler, the miniature diffusion sources and samplers were deployed in a typical home; six PFT sources were uniformly deployed, three on each level of a two-story house. Multiple location sampling, as well as sampling in rooms with and without a miniature source, demonstrated that even in a house without forced-air circulation, a well-mixed modeling approach is justified. Analyses of the tracer samplers were performed back in the laboratory with an automatic electron-capture gas-chromatography system. The effects of the inside/outside temperature differential, as well as that of an open fireplace compared with a wood-burning stove, on the measured air infiltration rates were clearly demonstrated. Comparisons of the PFT tracer method with that of the SF6 tracer decay approach showed the results of the two methods to be identical within experimental precision. With this miniature source and sampling tracer kit, infiltration rates in the range 0.2–5 air changes per hour can be measured over time-averaged periods of as little as 1 day up to several years.
The main objective of this work was to quantify and characterize the major indoor air contaminants present in different stages of a municipal WWTP, including microorganisms (bacteria and fungi), carbon dioxide, carbon monoxide, hydrogen sulfide ammonia, formaldehyde, and volatile organic compounds (VOCs). In general, the total bacteria concentration was found to vary from 60 to >52,560 colony-forming units (CFU)/m(3), and the total fungi concentration ranged from 369 to 14,068 CFU/m(3). Generally, Gram-positive bacteria were observed in higher number than Gram-negative bacteria. CO(2) concentration ranged from 251 to 9,710 ppm, and CO concentration was either not detected or presented a level of 1 ppm. H(2)S concentration ranged from 0.1 to 6.0 ppm. NH(3) concentration was <2 ppm in most samples. Formaldehyde was <0.01 ppm at all sampling sites. The total VOC concentration ranged from 36 to 1,724 μg/m(3). Among the VOCs, toluene presented the highest concentration. Results point to indoor/outdoor ratios higher than one. In general, the highest levels of airborne contaminants were detected at the primary treatment (SEDIPAC 3D), secondary sedimentation, and sludge dehydration. At most sampling sites, the concentrations of airborne contaminants were below the occupational exposure limits (OELs) for all the campaigns. However, a few contaminants were above OELs in some sampling sites.
Airborne viruses remain one of the major public health issues worldwide. Detection and quantification of airborne viruses is essential in order to provide information regarding public health risk assessment.
In this study, an optimized new, simple, low cost method for sampling of airborne viruses using Low Melting Agarose (LMA) plates and a conventional microbial air sampling device has been developed. The use of LMA plates permits the direct nucleic acids extraction of the captured viruses without the need of any preliminary elution step. Molecular detection and quantification of airborne viruses is performed using real-time quantitative (RT-)PCR (Q(RT-)PCR) technique. The method has been tested using Adenoviruses (AdVs) and Noroviruses (NoVs) GII, as representative DNA and RNA viruses, respectively. Moreover, the method has been tested successfully in outdoor experiments, by detecting and quantifying human adenoviruses (HAdVs) in the airborne environment of a wastewater treatment plant.
The great advantage of LMA is that nucleic acids extraction is performed directly on the LMA plates, while the eluted nucleic acids are totally free of inhibitory substances. Coupled with QPCR the whole procedure can be completed in less than three (3) hours.
An increase in global population, coupled with intensive development of industry and agriculture, has resulted in the generation and accumulation of large amounts of waste around the world. The spread of pathogenic microorganisms, endotoxins, odours and dust particles in the air is an inevitable consequence of waste production and waste management. Thus, the risk of infections associated with wastewater treatment plants (WWTPs) has become of a particular importance in recent decades. Sewage and unstable sludge contain various pathogens such as viruses, bacteria, and human and animal parasites. These microorganisms can be transmitted to the ambient air in wastewater droplets, which are generated during aeration or mechanical moving of the sewage. Bioaerosols generated during wastewater treatment may therefore pose a potential health hazard to workers of these plants or to habitants of their surroundings. The degree of human exposure to airborne bacteria, fungi, endotoxin and other allergens may vary significantly depending upon the type and the capacity of a plant, kind of the facilities, performed activities and meteorological conditions.
The performance characteristics of three real-time influenza A/B virus reverse transcription-PCR (RT-PCR) assays and two real-time 2009 H1N1 RT-PCR assays were evaluated using previously characterized clinical specimens. A total of 150 respiratory specimens from children (30 influenza A/H1 virus-, 30 influenza A/H3 virus-, 30 2009 H1N1-, and 30 influenza B virus-positive specimens and 30 influenza virus-negative specimens) were tested with the CDC influenza A/B PCR (CDC), ProFlu(+) multiplex real-time RT-PCR assay (ProFlu(+)), and MGB Alert Influenza A/B & RSV RUO (MGB) assays. A second set of 157 respiratory specimens (100 2009 H1N1-, 22 seasonal influenza A/H1-, and 15 seasonal influenza A/H3-positive specimens and 20 influenza-negative specimens) were tested with a new laboratory-developed 2009 H1N1 RT-PCR and the CDC 2009 H1N1 assay. The overall sensitivities of the CDC, ProFlu(+), and MGB assays for detection of influenza A and B viruses were 100%, 98.3%, and 94%, respectively. The ProFlu(+) assay failed to detect one influenza A/H1 virus-positive specimen and yielded one unresolved result with another influenza A/H1 virus-positive specimen. The MGB assay detected 84/87 (96.5%) of influenza A and B viruses and 26/30 (86.6%) of 2009 H1N1 viruses. The new laboratory-developed 2009 H1N1 RT-PCR assay detected 100/100 (100%) 2009 H1N1 virus-positive specimens, while the CDC SW Inf A and SW H1 PCR assays failed to detect one and three low-positive 2009 H1N1-positive specimens, respectively. The CDC influenza A/B virus assay and the newly developed 2009 H1N1 RT-PCR assay with an internal control can be set up in two separate reactions in the same assay for routine clinical testing to detect influenza A and B viruses and to specifically identify the 2009 H1N1 influenza virus.
Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 x 10(1) to 1.5 x 10(3) CFU (colony forming units) m(-3), even for metalworking fluid highly contaminated by bacteria (up to 2.4 x 10(9) CFU mL(-1)). Inhalable dust varied between < 0.1 to 2.6 mg m(-3), while air exchange rates were mostly below the standard (4 h(-1)) for this type of workplace, between 0.6 to 14.2 h(-1). Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m(-3), which is below the threshold limit value (TLV) (ACGIH) of 5 mg m(-3). Airborne endotoxin concentrations ranged from undetectable to 183 EU m(-3) (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated.
mothur aims to be a comprehensive software package that allows users to use a single piece of software to analyze community
sequence data. It builds upon previous tools to provide a flexible and powerful software package for analyzing sequencing
data. As a case study, we used mothur to trim, screen, and align sequences; calculate distances; assign sequences to operational
taxonomic units; and describe the α and β diversity of eight marine samples previously characterized by pyrosequencing of
16S rRNA gene fragments. This analysis of more than 222,000 sequences was completed in less than 2 h with a laptop computer.
It was previously demonstrated that microbial communities of pig manure were composed of both bacteria and archaea. Recent
studies have shown that bacteria are aerosolized from pig manure, but none have ever focused on the airborne archaeal burden.
We sought here to develop and apply molecular ecology approaches to thoroughly characterize airborne archaea from swine confinement
buildings (SCBs). Eight swine operations were visited, twice in winter and once during summer. Institute of Occupational Medicine
cassettes loaded with 25-mm gelatin filters were used to capture the inhalable microbial biomass. The total genomic DNA was
extracted and used as a template for PCR amplification of the archaeal 16S rRNA gene. High concentrations of archaea were
found in SCB bioaerosols, being as high as 108 16S rRNA gene copies per cubic meter of air. Construction and sequencing of 16S rRNA gene libraries revealed that all sequences
were closely related to methanogenic archaea, such as Methanosphaera stadtmanae (94.7% of the archaeal biodiversity). Archaeal community profiles were compared by 16S rRNA gene denaturing gradient gel
electrophoresis. This analysis showed similar fingerprints in each SCB and confirmed the predominance of methanogenic archaea
in the bioaerosols. This study sheds new light on the nature of bioaerosols in SCBs and suggests that archaea are also aerosolized
from pig manure.
In order to assess the potential exposure hazard to workers and people living in the immediate surroundings of an area characterized by an open composting facility and a wastewater treatment plant, a quantitative and a qualitative analysis of airborne microorganisms were carried out. Air sampling was performed once a week for four consecutive weeks in summer and winter. Six sites were selected as air sampling sites: one was upwind at approximately 40 m from the facilities; the other five were downwind at increasing distances from the facilities, with the furthest at 100 m away. Monitoring permitted us to verify the influence that the composting activities and wastewater treatment had on the bacterial and fungal contamination of the air. The results obtained have been expressed by means of contamination indexes that have already been used in previous works: a major microbiological contamination near the plants was evidenced. Near the facilities, mesophilic bacteria, psychrophilic bacteria and microfungi showed the highest median concentrations, respectively, of 307.5, 327.5 and 257.5 CFU/m(3). Moreover, the season generally influenced the concentration of the bacteria as well as of the fungi; higher in summer than in winter. The contamination index global index of microbial contamination (GIMC/m(3)) showed mean values of 4058.9 in summer and 439.7 in winter and the contamination index-amplification index (AI) showed values of 4.5 and 1.1 in the same seasons, respectively. Controlling the seasonal effect, mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae showed a significant decline in concentration with respect to upwind air samples and with increasing distance. Both GIMC and AI showed a significant decline with respect to upwind air samples by increasing the distance from facilities after adjusting for the seasonal effect. In conclusion, even if these plants do not represent a potential risk for nearby populations, they may pose a potential health risk for workers.
Bio-aerosols are airborne particles that are living (bacteria, viruses and fungi) or originate from living organisms. Their presence in air is the result of dispersal from a site of colonization or growth. The health effects of bio-aerosols including infectious diseases, acute toxic effects, allergies and cancer coupled with the threat of bioterrorism and SARS have led to increased awareness on the importance of bio-aerosols. The evaluation of bio-aerosols includes use of variety of methods for sampling depending on the concentration of microorganisms expected. There have been problems in developing standard sampling methods, in proving a causal relationship and in establishing threshold limit values for exposures due to the complexity of composition of bio-aerosols, variations in human response to their exposure and difficulties in recovering microorganisms. Currently bio-aerosol monitoring in hospitals is carried out for epidemiological investigation of nosocomial infectious diseases, research into airborne microorganism spread and control, monitoring biohazardous procedures and use as a quality control measure. In India there is little awareness regarding the quality of indoor air, mould contamination in indoor environments, potential source for transmission of nosocomial infections in health care facilities. There is an urgent need to undertake study of indoor air, to generate baseline data and explore the link to nosocomial infections. This article is a review on composition, sources, modes of transmission, health effects and sampling methods used for evaluation of bio-aerosols, and also suggests control measures to reduce the loads of bio-aerosols.
Bacteria- and virus-containing aerosols were studied during the late summer and fall seasons in a midwestern suburb of the United States before and during the start-up and operation of an unenclosed activated sludge wastewater treatment plant. The study showed that the air in this suburban area contained low-level densities of indicator microorganisms. After the plant began operating, the densities of total aerobic bacteria-containing particles, standard plate count bacteria, total coliforms, fecal coliforms, fecal streptococci, and coliphages increased significantly in the air within the perimeter of the plant. Before plant operations, bacteria were detected from five genera, Klebsiella, Enterobacter, Serratia, Salmonella, and Aeromonas. During plant operations, the number of genera identified increased to 11. In addition to those genera found before plant operations, Escherichia, Providencia, Citrobacter, Acinetobacter, Pasteurella, and Proteus, were also identified. Enteric viruses were detected in low densities from the air emissions of this plant. Only standard plate count bacteria remained at significantly higher than base-line densities beyond 250 m downwind from the center of the aeration tanks. Fecal streptococci and coliphages appeared to be more stable in aerosols than the other indicator microorganisms studied. In general, the densities of microorganism-containing aerosols were higher at night than during the day. The techniques used in this study may be employed to establish microorganism-containing aerosol exposure during epidemiological investigations.
Glass impingers (AGI-30) were used at a commercial sludge application site to determine the levels of airborne bacteria and pathogen indicators. Even though heterotrophic bacteria averaged 10(5) CFU/m3, none of the sites showed the presence of Salmonella spp. or indicators such as fecal coliforms or coliphages. Indicators such as H2S producers and pathogenic clostridia were present in locations having significant physical agitation of the sludge material. PCR-based ribotyping using the 16S-23S interspacer region is a promising method to identify the genetic relatedness and origins of airborne clostridia.
Biomethanization is a new technology used for green-waste valorization where organic waste is biodegraded by microbial communities under anaerobic conditions. The main product of this type of anaerobic digestion is a biogas used as an energy source. Moving and handling organic waste may lead to the emission of high concentrations of bioaerosols. High exposure levels are associated with adverse health effects amongst green environment workers. Fungal spores are suspected to play a role in many respiratory illnesses. There is a paucity of information related to the detailed fungal diversity in biomethanization facilities. The aim of this study was to provide an in-depth description of fungal bioaerosols in biomethanization work environments using a next-generation sequencing approach combined with real-time polymerase chain reaction (PCR). Two biomethanization facilities treating different wastes were visited during the sampling campaign (n = 16). Quantification of Penicillium/Aspergillus and Aspergillus fumigatus revealed a greater exposure risk during summer for both facilities visited. Concentrations of Penicillium and Aspergillus were similar in all work areas in both biomethanization facilities. Taxonomy analyses showed that the type of waste treated affects the fungal diversity of aerosols emitted. Although eight classes were evenly distributed in all samples, Eurotiomycetes were more dominant in the first facility and Agaricomycetes were dominant in the second one. A large diversity profile was observed in bioaerosols from both facilities showing the presence of pathogenic fungi. The following fungi detected are known allergens and/or are opportunistic pathogens: Aspergillus, Malassezia, Emericella, Fusarium, Acremonium, and Candida. Daily exposure to these fungi may put workers at risk. The information from this study can be used as a reference for minimizing occupational exposure in future biomethanization facilities.
Implications:
Biomethanization is a new technology used for green-waste valorization where organic waste is biodegraded by microbial communities. Effective waste management is increasingly recognized as a strategic approach for achieving newly created regulations concerning the disposal of organic residues; therefore, an expansion of facilities is expected. Workers' exposure to diverse fungal communities is certain, as fungi are ubiquitous and necessary in organic matter decomposition. Monitoring this occupational exposure is important in order to prevent workers' health problems.
Bioaerosols are commonly defined as biological particles suspended in the air. The concentration of bioaerosols found in the air of composting plants depend upon the source nature and composition, season, physical and mechanical factors such as wind and temperature. The aerosolization potential of particular microorganisms could significantly differ between species depending on morphological and biochemical characteristics, although this phenomenon is poorly understood. The aim of this study was to investigate, using new sequencing technologies and qPCR, the preferential aerosolization of microorganisms in different composting plants processing various raw materials. Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria constituted the major phyla of bacteria found in bioaerosols from compost. There is a clear association between microorganisms found in the air and in compost samples. Nevertheless, Actinobacteria-associated phyla or species are more likely to be enriched in air samples. Using new sequencing MiSeq Illumina® technology, this study demonstrates the preferential aerosolization of Actinobacteria and more specifically, clinically-relevant taxa such as Saccharopolyspora, Saccharomonospora, Streptomyces and Mycobacterium.
Composting is a natural dynamic biological process used to valorise putrescible organic matter. The composting process can involve vigorous movements of waste material piles, which release high concentrations of bioaerosols into the surrounding environment. There is a lack of knowledge concerning the dispersal of airborne microorganisms emitted by composting plants (CP) as well as the potential occupational exposure of composting workers. The aim of this study was to investigate the workers exposure to bioaerosols during working activities in three different types of composting facilities (domestic, manure, carcass) using two different quantification methods (cultivation and qPCR) for bacteria and moulds concentrations. As expected, even if there are differences between all CP frameworks, independently of the type of the raw compost used, the production of bioaerosols increases significantly during handling activities. Important concentrations of mesophilic moulds and mesophilic bacteria were noted in the working areas with a respective maximal concentration of 2.3x10⁵ CFU/m³ and 1.6x10⁵ CFU/m³. A. fumigatus and thermophilic Actinomycetes were also detected in all working areas for the 3 CP. This study emphases the risks for workers to being in contact with aerosolized pathogens such as Mycobacterium and Legionella and more specifically, L.pneumophila. The presence of high concentration of these bacteria in CP suggests a potential occupational health risk. This study may lead to recommendations for the creation of limits for occupational exposure. There is a need for identifying the standards exposure limits to bioaerosols in CP and efficient recommendation for a better protection of workers' health.
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Bioaerosols are among the less studied particles in the environment. The lack of standardization in sampling procedures, difficulties related to the effect of sampling processes on the integrity of microorganisms, and challenges associated with the application of environmental microbiology analyses and molecular and culture methods frighten many young scientists. Every microorganism has its own particularities and acts differently when aerosolized in various conditions. Because the air is an extremely biologically diluted environment, it is necessary to concentrate its content before any analysis is performed. Challenges faced when applying molecular methods to air samples reveal the need for a better standardization of approaches for cell and nucleic acid recovery, the choice of genetic markers, and interpretation of data. This paper presents a few of the limits and difficulties tackled when molecular methods are applied to bioaerosols, suggests some improvements by specifying the critical stages that should be considered when studying the microbial ecology of bioaerosols, and provides thoughtful insights on how to overcome the challenges encountered.
Schmltz, H., R. Wlgand (Instltut für Hygiene, U. Kliniken, D-6650 Homburg/ Saar, FRG), and W. Helnrich. Worldwide epidemiology of human adenovlrus infections. Am J Epidemiol 1983; 117: 455–66.
Approximately 25, 000 reports to WHO from 1967 to 1976 on isolations of adenovirus 1 to 31 showed an absolute frequency of Ad2, 1, 7, 3, 5, 6, 4, 8, and other species, in decreasing order. The relative frequency was analyzed by the X² method; only significant deviations (p < 0.05; in many cases p < 0.001) from chance distribution were taken into account. To avoid small numbers, the three adenovirus species of subgenus A (Ad12, 18, 31) and several species of subgenera B and D were analyzed as one group. The incidence of Ad8, 7 and 19, less so of Ad3 and 4, showed a periodicity over the years. No definite seasonal incidence pattern was found for the countries of the Northern Hemisphere. The Southern Hemisphere showed a higher incidence of Ad4 and 7, and subgenus B (without Ad3 and 7), and a lower incidence of Ad6, whereas subgenus A, Ad8, and 19 were rarely reported. Highly significant age predilections were subgenus A for infants, subgenus C for infants and small children, Ad3 for school children, Ad7 for school children and adults, Ad4, 8, and other species of subgenera B and D for adults. A predilection for males was observed In all species of subgenera B and C, and in Ad4 and 19. The association between virus infection and clinical syndromes was analyzed for children up to age 14 years and for adults separately. Subgenus C viruses, mainly Ad2, occurred frequently in Infections of the lower respiratory and gastrointestinal tract In both children and adults. An association with disease of the central nervous system, fever, and cardiovascular disease was seen in adults only. Ocular infections in both children and adults were associated with Ad3; only children showed an association with upper respiratory tract disease and fever. Ad7 was frequent in ocular disease and fever in children, and in respiratory infections in adults. For Ad4, no organ specificity was found. Ocular infections in both children and adults were associated with Ad8; only children showed an association with upper respiratory tract disease. Subgenus A was associated with gastrointestinal disease in children. The hypothesis that all the adenovirus species from one subgenus may have similar epidemiologic and pathogenic properties appears to be largely true for subgenus C viruses. In subgenus B, many differences were found between Ad3 and 7, and other viruses of subgenus B.
Subway systems worldwide transport more than 100 million people daily, therefore air quality on station platforms and inside trains is an important urban air pollution issue. We examined the microbiological composition and abundance in space and time of bioaerosols collected in the Barcelona subway system during a cold period. Quantitative PCR was used to quantify total bacteria, Aspergillus fumigatus, influenza A and B and rhinoviruses. Multitag 454 pyrosequencing of the 16S rRNA gene was used to assess bacterial community composition and biodiversity. The results showed low bioaerosol concentrations regarding the targeted microorganisms, although the bacterial bioburden was rather high (10(4) bacteria/m(3) ). Airborne bacterial communities presented a high degree of overlap among the different subway environments sampled (inside trains, platforms and lobbies) and were dominated by a few widespread taxa, with Methylobacterium being the most abundant genus. Human related microbiota in sequence dataset and ascribed to potentially pathogenic bacteria were found in low proportion (maximum values below 2% of sequence readings) and evenly detected. Hence, no important biological exposure marker was detected in any of the sampled environments. Overall, we found that commuters are not the main source of bioaerosols in the Barcelona subway system. This article is protected by copyright. All rights reserved.
Bioaerosols significantly affect atmospheric processes while they undergo long-range vertical and horizontal transport and influence atmospheric chemistry and physics and climate change. Accumulating evidence suggests that exposure to bioaerosols may cause adverse health effects, including severe disease. Studies of bioaerosols have primarily focused on their chemical composition and largely neglected their biological composition and the negative effects of biological composition on ecosystems and human health. Here, current molecular methods for the identification, quantification, and distribution of bioaerosol agents are reviewed. Modern developments in environmental microbiology technology would be favorable in elucidation of microbial temporal and spatial distribution in the atmosphere at high resolution. In addition, these provide additional supports for growing evidence that microbial diversity or composition in the bioaerosol is an indispensable environmental aspect linking with public health.
To characterize the emission of microbial aerosols from the widely used municipal sewage treatment plants (MSTP) in China, an Andersen six-stage impactor and the culture method were employed to determine the concentrations and size distributions of airborne viable bacteria, fungi and actinomycetes in a sewage treatment plant with an oxidation ditch process in Xi’an in summer. The results showed that the concentrations and size distributions of each of the airborne microorganisms varied greatly at different phases of sewage treatment process. The highest bacteria (7866 ± 970 CFU/m 3 ) and actinomycetes concentrations (2139 ± 229 CFU/m 3 ) were found in the sludge-dewatering house while the highest fungi concentration (2156 ± 119 CFU/m 3 ) at the oxidation ditch. The particle size distributions showed that similar singlepeak pattern for airborne actinomycetes, bacteria and fungi. Another important finding was that about 52% of airborne bacteria, 62% of airborne fungi and 65% of airborne actinomycetes were in respirable size range (less than 3.3 μm), indicating that most microbial aerosols from MSTP could easily penetrate into the human alveolus. Finally, the order of the count median diameters of different microbial aerosols was found to be similar at each phase, that is, airborne bacteria > airborne fungi > airborne actinomycetes. This implied that airborne actinomycetes emitted from MSTP might have a more significant effect on public health and urban air quality than bacteria and fungi.
Noroviruses represent the most important cause of acute gastroenteritis worldwide; however, currently no licensed vaccine
exists. Widespread vaccination that minimizes overall norovirus disease burden would benefit the entire population, but targeted
vaccination of specific populations such as healthcare workers may further mitigate the risk of severe disease and death in
vulnerable populations. While a few obstacles hinder the rapid development of efficacious vaccines, human trials for virus-like
particle (VLP)-based vaccines show promise in both immune response and protection studies, with availability of vaccines being
targeted over the next 5–10 years. Ongoing work including identification of important norovirus capsid antigenic sites, development
of improved model systems, and continued studies in humans will allow improvement of future vaccines. In the meantime, a better
understanding of norovirus disease course and transmission patterns can aid healthcare workers as they take steps to protect
high-risk populations such as the elderly and immunocompromised individuals from chronic and severe disease.
Amplified marker-gene sequences can be used to understand microbial community structure, but they suffer from a high level of sequencing and amplification artifacts. The UPARSE pipeline reports operational taxonomic unit (OTU) sequences with ≤1% incorrect bases in artificial microbial community tests, compared with >3% incorrect bases commonly reported by other methods. The improved accuracy results in far fewer OTUs, consistently closer to the expected number of species in a community.
Airborne particles are present throughout our environment. They come in many different forms, such as dusts, fumes, mists, smoke, smog, or fog. These aerosols affect visibility, climate, and our health and quanlity of life. This book covers the properties, behaviour, and measurement of aerosols. This is a basic textbook for people engaged in industrial hygiene, air pollution control, radiation protection, or environmental science who must, in the practice of their profession, measure, evaluate, or control airborne particles. It is written at a level suitable for professionals, graduate students, or advanced undergraduates. It assumes that the student has a good background in chemistry and physics and understands the concepts of calculus. Although not written for aerosol scientists, it will be useful to them in their experimental work and will serve as an introduction to the field for students starting such careers. Decisions on what topics to include were based on their relevance to the pratical application of aerosol science, which includes an understanding of the physical and chemical prinicples that underlie the behaviour of aerosols and the instruments used to measure them. (from preface)
Bioaerosols are formed by suspension of particles of biological origin in the air. They come from a wide range of sources, many of which are associated with particular occupations. Many of the components have been implicated in occupational lung disease. The agents include viruses: bacteria; actinomycete, fungal, moss and fern spores; algal and plant cells; insects and mites and their fragments and excreta; proteins from plant and animal sources; enzymes, antibiotics and other products from biotechnological processes; endotoxins from Gram-negative bacteria: and mycotoxins and glucans from fungi. Infections from pathogenic viruses, bacteria and fungi may occur in some work environments but more often the symptoms encountered are of mucous membrane irritation, bronchitis and obstructive pulmonary disease, allergic rhinitis and asthma, allergic alveolitis (granulomatous pneumonitis) or organic dust toxic syndrome (inhalation fever or toxic pneumonitis). Exposure to bioaerosols may occur in many different occupations, especially those in which stored products are handled or where aerosols are created as a result of leaks from equipment intentionally or accidentally contaminated with microorganisms or during particular operations as, for instance, in laboratories and during post-mortem or surgical procedures. This article reviews the spectrum of agents involved in occupational lung disease, the work environments in which they occur, the characteristics of the diseases and their prevention.
The production of microbial aerosols by urban sewage treatment plants may have wide hygienic implications which call for careful evaluation: exposure to such aerosols may in fact represent a health hazard for plant workers and nearby residents alike. This paper describes the results of a study analysing the degree of microbial contamination at different levels of treatment at several plants in the City of Leghorn (Livorno, Italy). Monthly aerosol samples were collected with an agar impact sampler from January to November 1996, from different sites at an activated sludge plant, an anaerobic sludge plant and a wastewater washing station. The total bacterial and coliform counts were determined, and pathogenic enteric bacteria and viruses were determined. These same parameters were also measured in wastewater and sludge samples obtained at the same sites. The results revealed that high-grade airborne contamination existed at several of the studied sites. In particular, pathogenic enteric bacteria (Salmonella enteritidis and S. boydii) were isolated in 2% of the samples (540 l per sample), reovirus in 46% and enterovirus in 9% (1800 litres per sample in indoor environment and 3000 l outdoor), always in association with the former virus. The biological parameters measured had no evident correlation with meteorological factors such as temperature, relative humidity or wind characteristics. Viral contamination proved to be quite wide-spread and detectable even in the presence of low levels of bacterial contamination. Although virological analysis have been only qualitative, and the different volumes examined for viruses and bacteria cannot allow us to appraise with accuracy the association between these two parameters, the viral presence along with low bacteria contamination suggests more dedicated studies to address with greater accuracy the quantitative aspects of this association. However the monitoring performed allowed for a determination of the areas of greatest potential risk for plant workers, and the preventive measures most suitable to guaranteeing their safety.
Liquid manure from storage pits in twenty-three swine confinement operations was characterized by taking multiple measurements, over a 6-month period, of twelve different chemical and physical parameters. Low temperature, high ammonia content, excess hydrogen ion content (as measured by low bicarbonate alkalinity and excess Volatile Acids) and excess Volatile Solids were often inhibitory or toxic for anaerobic digestion in the pits. Relative to optimal anaerobic digestion, bacterial metabolic reaction rates are slow, production rates of methane and other gases are relatively low, odorous intermediate products (organic acids and sulfur-containing compounds) are relatively high and waste stabilization is relatively low. Conditions favoring the production of hydrogen sulfide, ammonia and other odorous and toxic compounds prevail over conditions favoring methane production. These characteristics were accentuated in grower and finishing buildings as compared with farrowing buildings.High sulfate concentrations in water sources are potentially hazardous because they increase the sulfide content of the manure and therefore increase the potential exposure of workers and swine to toxic levels of hydrogen sulfide.Only a portion of the NH3 present in the air of confinement buildings comes from the manure pit. Therefore, eliminating the pit under the building would not eliminate the air ammonia problem.Manure in farrowing buildings could possibly be treated in the pit to enhance stabilization by controlling temperature, water content and loading rates. However, in-the-pit treatment to enhance anaerobic digestion in nursery, grower and finishing buildings may be more difficult because of the extremely adverse biological conditions in these pits.
The nose is an integral part of the upper airway and the first contact of the body with inspired air. It is located in close proximity to several related airway structures that include the ears, paranasal sinuses, and eyes. It is also closely linked to the lower airway. Multiple lines of evidence support a close interaction and influence of the nose on these contiguous and distant organs via neural reflexes and systemic inflammatory processes. These interactions are reviewed in light of existing evidence.
First isolated in California, USA, in 1969, enterovirus 71 (EV71) is a major public health issue across the Asia-Pacific region and beyond. The virus, which is closely related to polioviruses, mostly affects children and causes hand, foot, and mouth disease with neurological and systemic complications. Specific receptors for this virus are found on white blood cells, cells in the respiratory and gastrointestinal tract, and dendritic cells. Being an RNA virus, EV71 lacks a proofreading mechanism and is evolving rapidly, with new outbreaks occurring across Asia in regular cycles, and virus gene subgroups seem to differ in clinical epidemiological properties. The pathogenesis of the severe cardiopulmonary manifestations and the relative contributions of neurogenic pulmonary oedema, cardiac dysfunction, increased vascular permeability, and cytokine storm are controversial. Public health interventions to control outbreaks involve social distancing measures, but their effectiveness has not been fully assessed. Vaccines being developed include inactivated whole-virus, live attenuated, subviral particle, and DNA vaccines.
Hypersensitivity pneumonitis of machinists associated with metalworking fluids (MWF) was recently linked to Mycobacterium immunogenum. In addition to Mycobacterium, impacts of continuous and massive contact to other micro-organisms, such as Pseudomonas, were little studied. This report intended to quantify and characterize the microbial load of 44 in-use MWF.
The main biodiversity of MWF was assessed using cultural methods, quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE). Total bacteria concentrations ranged from undetectable to 10(9) 16S rRNA gene copies per millilitre. Concentrations obtained by qPCR were up to five orders of magnitude higher than by culture, suggesting that MWF contamination is generally underestimated. Two samples showed high concentrations of Myco. immunogenum (1.55 x 10(7) and 3.49 x 10(5) 16S rRNA gene copies per millilitre). The overall biodiversity was low, as observed by culture and DGGE, and was comparable to data found in the literature. Pseudomonas pseudoalcaligenes was by far the main bacteria found in MWF samples (33 out of 44), followed by Ochrobactrum anthropi (32 out of 44). There was no significant relationship between the biodiversity profiles and the kind of MWF or equipment used, making it difficult to predict which micro-organisms will colonize each particular MWF.
Very high concentrations of bacteria were found in most MWF studied and limited biodiversities were observed. Many species of micro-organisms were retrieved from MWF samples, but they were mostly colonized by Pseudomonas pseudoalcaligenes and Ochrobactrum anthropi.
The major micro-organisms observed or recovered in this study from in-use MWF were present in very high concentrations, and thus further studies are needed to confirm their role in workers' respiratory disorders or health-related problems.
Pseudomonads are a large group of free-living bacteria that live primarily in soil, seawater, and fresh water. They also colonize plants and animals, and are frequently found in home and clinical settings. Pseudomonads are highly versatile and can adapt to a wide range of habitats, and can even grow in distilled water. This adaptability accounts for their constant presence in the environment. They have an extensive impact on ecology, agriculture, and commerce. They are responsible for food spoilage and degradation of petroleum products and materials. In agriculture, pseudomonads rank among the most important plant pathogens. In normal healthy humans, they are responsible for eye and skin diseases. They also cause serious life-threatening illnesses in burn and surgical patients and in immunocompromised individuals. Contamination of recreational waters and tap water has been associated with outbreaks of Pseudomonas; however, the relative role water plays in the transmission of this bacterium to humans is still unclear. The goal of this review is to assess existing literature on the potential risks associated with waterborne Pseudomonas aeruginosa.
This work reviews (i) the most recent information on waste arisings and waste disposal options in the world, in the European Union (EU), in Organisation for Economic Co-operation and Development (OEDC) countries, and in some developing countries (notably China) and (ii) the potential direct and indirect impact of waste management activities on health. Though the main focus is primarily on municipal solid waste (MSW), exposure to bioaerosols from composting facilities and to pathogens from sewage treatment plants are considered. The reported effects of radioactive waste are also briefly reviewed. Hundreds of epidemiological studies reported on the incidence of a wide range of possible illnesses on employees of waste facilities and on the resident population. The main conclusion of the overall assessment of the literature is that the evidence of adverse health outcomes for the general population living near landfill sites, incinerators, composting facilities and nuclear installations is usually insufficient and inconclusive. There is convincing evidence of a high risk of gastrointestinal problems associated with pathogens originating at sewage treatment plants. In order to improve the quality and usefulness of epidemiological studies applied to populations residing in areas where waste management facilities are located or planned, preference should be given to prospective cohort studies of sufficient statistical power, with access to direct human exposure measurements, and supported by data on health effect biomarkers and susceptibility biomarkers.
The immune system provides an essential defence against invading pathogens. However, bacteria have evolved numerous strategies to overcome this defence, many of which facilitate systemic dissemination of the pathogen. Nevertheless, the host has evolved many mechanisms to detect and protect against pathogens in the vasculature. Recent studies using new imaging approaches and new mouse models are revealing previously unappreciated functions of this intravascular aspect of the immune system. In this Review, we summarize recent work in this field, highlighting in vivo imaging studies that examine the behaviour of both the immune system and bacteria in the highly dynamic microvasculature.
The concentrations of airborne culturable microorganisms were determined in wastewater and sludge treatment processes of seven sewage treatment plants. Two types of coliphages, Salmonella and total viable bacteria were sampled by the BioSampler and the numbers of faecal coliforms and enterococci were obtained from the Andersen 6-stage impactor. The BioSampler recovered higher numbers of airborne coliphage viruses than has been measured with other liquid samplers in previous studies, suggesting that this sampler has improved efficiency for sampling airborne coliphages. Airborne coliphages were detected in many stages of the wastewater or sludge treatment process. The highest microbiological air contaminations were found in pre-treatment and aerated grit separation stages of the operation. This was attributed to aerosolisation of microorganisms by mechanical handling or forced aeration. Aeration and settling processes located outdoors caused low microbial concentrations, but the brush aerator released more microorganisms into the air. Our results emphasize the necessity for controlling the exposure of sewage workers to airborne microorganisms, especially in process areas that involve mechanical agitation or forced aeration of wastewater.
The standard diagnosis of rotavirus gastroenteritis is based on the demonstration of rotavirus antigen in stools using an enzyme immunoassay (EIA). In this study, a one-step quantitative RT-PCR (Q-PCR) was used for sensitive detection of rotavirus in diarrheal stools. The primers and TaqMan probe for the Q-PCR were selected from a highly conserved region of the non-structural protein 3 (NSP3) of rotavirus. After validation, the test was applied to study rotavirus EIA positive (N=25) and EIA negative (N=143) stool specimens from cases of acute gastroenteritis of all degrees of severity in a prospective follow-up cohort of infants from 2 months to 2 years of age. Q-PCR detected all 25 EIA positive rotavirus antigens and seven additional cases that were rotavirus EIA negative, i.e. 28% more rotavirus positive cases than identified by EIA. It is concluded that Q-PCR using primers targeted at NSP3 is a rapid and sensitive method for diagnosing acute rotavirus gastroenteritis.
We investigated transmission of rhinovirus colds by examining shedding by infected patients, survival of virus outside the host, and inoculation of susceptible persons. Two of 25 infected persons expelled virus in a cough or sneeze; four of 10 had virus on their hands. Dried rhinovirus could be picked up by the fingers from skin or environmental surfaces. Four of 11 volunteers became infected after touching their nasal or conjunctival mucosa with fingers previously contaminated by rubbing a dried drop of rhinovirus. Adults expose the nasal or conjunctival mucosa to the fingers frequently under natural conditions. Transmission of rhinoviruses from infected to susceptible persons under natural conditions may proceed by transfer of virus from the hands of the infected person to an intermediary surface or directly to the fingers of the susceptible recipient. Infection then results from self-inoculation of eyes or nose with virus on the fingers. (N Engl J Med 288:1361–1364, 1973)
Coliphages and enteroviruses were monitored over 12 months in sewage and air adjacent to an activated sludge plant. Both showed temporal variation but the mean count of phages in enterovirus-positive samples was not significantly different from that in enterovirus-negative samples. Hence coliphages are not necessarily a good indicator of enteroviruses in sewage and aerosols.
Human respiratory health hazards for people working in livestock confinement buildings have been recognized since 1974. However, before comprehensive control programs can be implemented, more knowledge is needed of specific hazardous substances present in the air of these buildings, and at what concentrations they are harmful. Therefore, a medical epidemiological and exposure-response study was conducted on 207 swine producers using intensive housing systems (108 farms).
Dose-response relationships between pulmonary function and exposures are reported here. Positive correlations were seen between change in pulmonary function over a work period and exposure to total dust, respirable dust, ammonia, respirable endotoxin, and the interactions of age-of-producer and dust exposure and years-of-working-in-the-facility and dust exposure. Relationships between baseline pulmonary function and exposures were not strong and therefore, not pursued in this study.
The correlations between exposure and response were stronger after 6 years of exposure. Multiple regression models were used to identify total dust and ammonia as the two primary environmental predictors of pulmonary function decrements over a work period. The regression models were then used to determine exposure concentrations related to pulmonary function decrements suggestive of a health hazard. Total dust concentrations ⩾ 2.8 mg/m3 were predictive of a work period decrement of ⩾ 10% in FEV1. Ammonia concentrations of ⩾ 7.5 ppm were predictive of a ⩾ 3% work period decrement in FEV1. These predictive concentrations were similar to a previous doseresponse study, which suggested 2.5 mg/m3 of total dust and 7 ppm of NH3 were associated with significant work period decrements. Therefore, dust ⩾ 2.8 mg/m3 and ammonia ⩾ 7.5 ppm should be considered reasonable evidence for guidelines regarding hazardous exposure concentrations in this work environment.
The nose is the first organ system encountered by inhaled air and its associated pollutants. Pollutants are deposited during inspiration through the nose. They accumulate on mucus and are absorbed in the nasal mucosa, resulting in a number of deleterious effects on the body. Irritation of the nose and sinus from these pollutants, resulting from direct contact with the nasal mucosa, leads to inflammation, edema, swelling, and blocked sinuses. The result is acute and chronic sinusitis. Absorption of these chemicals into the body produces systemic effects. Their effect on the immune system, although subtle, leads to dramatic changes in the allergic diathesis. The T suppressor cell is the most sensitive cell of the immune system and the first to be affected by exposure to chemical pollutants. Diminution of the suppressor activity and the relative increase in helper activity in turn lead to increased immunoglobulin production and the manifestation of allergy symptoms. The underlying biochemical reaction is caused by the effects of pollutants on the T suppressor cell. Patients with existing allergies become brittle and difficult to treat with the exacerbation of the allergic diathesis. Removal of these chemical pollutants from the body as quickly as possible is essential for effective treatment of this problem. Dietary antioxidants help reduce the oxidizing effect of the pollutants and act as conjugators to remove the pollutants from the body.