The aerosolization process of fungal propagules of three species (Aspergillus versicolor, Penicillium melinii, and Cladosporium cladosporioides) was studied by using a newly designed and constructed aerosolization chamber. We discovered that fungal fragments are aerosolized simultaneously with spores from contaminated agar and ceiling tile surfaces. Concentration measurements with an optical particle counter showed that the fragments are released in higher numbers (up to 320 times) than the spores. The release of fungal propagules varied depending on the fungal species, the air velocity above the contaminated surface, and the texture and vibration of the contaminated material. In contrast to spores, the release of fragments from smooth surfaces was not affected by air velocity, indicating a different release mechanism. Correlation analysis showed that the number of released fragments cannot be predicted on the basis of the number of spores. Enzyme-linked immunosorbent assays with monoclonal antibodies produced against Aspergillus and Penicillium fungal species showed that fragments and spores share common antigens, which not only confirmed the fungal origin of the fragments but also established their potential biological relevance. The considerable immunological reactivity, the high number, and the small particle size of the fungal fragments may contribute to human health effects that have been detected in buildings with mold problems but had no scientific explanation until now. This study suggests that future fungal spore investigations in buildings with mold problems should include the quantitation of fungal fragments.Water damage in buildings is common and is often associated with mold problems. In North America, cross-sectional questionnaire studies have found that 27 to 36% of homes have mold problems (9, 51). Studies that included indoor air quality measurements have shown even higher numbers, from 42 to 56% (8, 11). In Europe, the prevalence of damp and moldy homes has been reported to be 17 to 46% for Great Britain (5,23,34,42), 15 to 18% for The Netherlands (3, 55,56), and 15% for Finland (41). Alarmingly, signs of present or previous moisture-related defects were found in 80% of randomly selected private homes investigated by civil engineers trained to recognize the signs of water leaks or condensation (37).Increased prevalence of water-damaged buildings and subsequent fungal contamination may contribute to the noted increase in allergic diseases. Fungi can affect human health in a variety of ways. Possible reactions generally fall into one of three groups: allergic reactions (sensitization and immune responses, i.e., asthma, allergic rhinitis, or hypersensitivity pneumonitis), infections (growth of the fungus in or on the body, e.g., aspergillosis), and toxic responses (24,30,45). The toxic reactions are mainly connected with the secondary fungal metabolites, i.e., mycotoxins, but the role of cell wall components, such as ␤-(133)-D-glucans, has also been reported (4,26,29,45,47,50). In addition, expos...

Aerosols of water contaminated with Legionella bacteria constitute the only mode of exposure for humans. However, the prevention strategy against this pathogenic bacteria risk is managed through the survey of water contamination. No relationship linked the Legionella bacteria water concentration and their airborne abundance. Therefore, new approaches in the field of the metrological aspects of Legionella bioaerosols are required. This study was aimed at testing the main principles for bioaerosol collection (solid impaction, liquid impingement and filtration) and the in situ hybridization (FISH) method, both in laboratory and field assays, with the intention of applying such methodologies for airborne Legionella bacteria detection while showering. An aerosolization chamber was developed to generate controlled and reproducible L. pneumophila aerosols. This tool allowed the identification of the liquid impingement method as the most appropriate one for collecting airborne Legionella bacteria. The culturable fraction of airborne L. pneumophila recovered with the liquid impingement principle was 4 and 700 times higher compared to the impaction and filtration techniques, respectively. Moreover, the concentrations of airborne L. pneumophila in the impinger fluid were on average 7.0 x 10(5) FISH-cells m(-3) air with the fluorescent in situ hybridization (FISH) method versus 9.0 x 10(4) CFU m(-3) air with the culture method. These results, recorded under well-controlled conditions, were confirmed during the field experiments performed on aerosols generated by hot water showers in health institutions. This new approach may provide a more accurate characterization of aerobiocontamination by Legionella bacteria.

Individuals with viral infection could possibly emit an infectious aerosol. The distinction between exhaled breaths of infected and healthy individuals should facilitate an understanding of the airborne transmission of infections. In this context, the present study is aimed at distinguishing healthy individuals from symptomatic ones by the study of their exhaled breath. A setup composed of a modified hood connected to an electrical low pressure impactor, which allows for the study of a wide range of particle sizes (from 7 nm to 10 lm), has been developed in order to collect exhaled breaths. This setup has been used with seventy eight volunteers. The results obtained There was not a specific size distribution obtained for the individuals with symptoms. As a consequence, further research on the exhaled breath should be undertaken with symptomatic volunteers and would require the analysis of this wide range of particle sizes.

ABSTRACTLegionellaspecies are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics ofLegionellaspp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics ofLegionellaand eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenicLegionellaspecies remained after the heat shock and chemical treatments (Legionella pneumophilaandLegionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebaesp.,Vannellasp., andHartmanella vermiformis) and after the first heat shock treatment, but onlyH. vermiformisremained. However, another protozoan affiliated with Alveolata, which is known as a host cell forLegionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effectiveLegionelladisinfection may be dependent on the elimination of these important microbial components. We suggest that eradicatingLegionellain hot water networks requires better study of bacterial and eukaryal species associated withLegionellain biofilms.

Aims:  (i) To develop an analytical tool in order to evaluate the effectiveness of anti‐Legionella treatment in biofilm and (ii) study the fate of Legionella populations in water and biofilm after applying a heat shock treatment. Methods and Results:  A pilot‐scale unit simulating a hot water system was built and designed by the Scientific and Technical Building Centre (CSTB, France). At the end of the contamination period, a stable cultivable Legionella spp. concentration of 5 × 105 CFU l−1 was obtained. Two heat shock treatments (70°C for 30 min) were applied. The results showed that the first treatment had a transitional effect on the abatement of Legionella concentrations, while the second treatment had no detectable effect on Legionella populations in water and biofilm. The DAPI (4′,6′‐diamidino‐2‐phenylindole), Legionella PCR and GVPC (glycocolle vancomycin pyrophosphate cycloheximide) counts measured in the dead leg water of the Test Loop were 1, 2 and 2 log units higher than results found in the Test Loop water. Moreover, Legionella spp. count in tap water was about 104 GU l−1. These analyses revealed that they are responsible for the rapid recolonization as well as the uncomplete destroyed biofilm. In addition, a resistance test was conducted and showed that Legionella in the second heat shock treatment was not thermo‐resistant but thermo‐acclimated. Conclusion:  Thermal disinfection does not seem to be efficient enough to eliminate Legionella when it is used as a curative treatment. Significance and Impact of the Study:  This work could help water managers for a better management of water network and for a better control of Legionella.