Microbes in Air and Bioaerosols

1. Microbes in Air and Bioaerosols

2. Definition-Microorganisms or particles, gases, vapors, or fragments of biological origin (i.e., alive or released from a living organism) that are in the air. • Bioaerosols are everywhere in the environment. • Some bioaerosols, when breathed in, can cause diseases including pneumonia, asthma, rhinitis (e.g. cold, hay fever), and respiratory infection. • Some bioaerosols can also infect the eyes and via ingestion (swallowed) Bioaerosols

3. Airborne transmission is possible for essentially all classes of microbes: viruses, bacteria, fungi and protozoans. • Any respiratory pathogen able to survive aerosolization and air transport is considered a potential cause of airborne disease. • Aerosols: Airborne particles, either solid or liquid, about 0.5 to 20 microns in diameter, that remain airborne for extended periods of time. • Droplets: >20 (usually 100+) microns in diameter; settle rapidly or evaporate to form droplet nuclei in the aerosol size range. Airborne Microbes and Aerosols

4. Living Source Examples Microorganisms (microbes): • Bacteria Legionella, Actinomycetes, endotoxins • Fungi Histoplasma, Alternaria, Pencillium, Aspergillus, Stachybotrys aflatoxins, aldehydes, alcohols • Protozoa Naegleria, Acanthamoeba • Viruses Rhinoviruses (colds), Influenza (flu) • Algae Chlorococus Green plants Ambrosia (ragweed) pollen Arthropods Dermatophagoides (dust mites) feces Mammals horse or cat dander Some Examples of Bioaerosols

5. Diseases Caused by Bioaerosols: Diseases Caused by Bioaerosols:

6. Result from exposure to antigens (of indoor bioaerosols) that stimulate an allergic response by the body's immune system. • Susceptiblity varies among people. • Diseases usually are diagnosed by a physician. • Once an individual has developed a hypersensitivity disease, a very small amount of the antigen may cause a severe reaction. • Hypersensitivity diseases account for most of the health problems due to indoor bioaerosols. Hypersensitivity or Allergic Diseases

7. Building-related asthma: • symptoms -an hour of exposure or 4-12 hours after exposure. • by airborne fungi such as Altemaria, glycoproteins from fungi, proteases from bacteria, the algae Chlorococus, ragweed pollen, dust mites, and dander from cats. 1. Hypersensitivity or Allergic Diseases

8. Allergic rhinitis: stuffiness of the nose, clear discharge from the nose, itchy nose, and sneezing. Itching and puffy eyes. • All the indoor bioaerosols listed under building-related asthma except the bacteria proteases also cause rhinitis.

9. Hypersensitivity pneumonitis(extrinsic allergic alveolitis): • Can be an acute, recurrent pneumonia with fever, cough, chest tightness, and fluids entering the lungs. • to shortness of breath, fatigue, weight loss and thickening and scarring of the lungs. • microorganisms associated with hypersensitivity pneumonitis: fungi such as Penicillium and Sporobolomyces, bacteria such as Thermoactinomyces, and protozoa such as Acanthamoeba. 1. Hypersensitivity or Allergic Diseases

10. Humidifier fever: fever, chills, muscle aches, and malaise (general feeling of being unwell), but no lung symptoms. • The symptoms usually start within 4-8 hours of exposure and end within 24 hours without long-term effects

11. Reservoirs and amplifiers: • Hot water systems • circulating water ventilation systems (cooling towers) • Plumbing (e.g., shower heads). • Hot tubs, whirlpools, etc. • Produce fresheners Cleveland Auto plant outbreak, March, 2001: • Plant cooling tower is considered a possible source of the outbreak. • But, more than 100 other internal water sources -- favorite breeding grounds for the Legionella bacteria -- were also under investigation…. Legionella: Legionellosis and Pontiac Fever

12. Pontiac fever: also caused by Legionella. • A "flu-like" illness with fever, chills, headache, myalgia (pain in the muscles), cough, nausea, and breathlessness. • Pneumonia does not occur. • Usually lasts 2-5 days. • Same sources as for Legionnaires' disease

13. Legionnaire's disease: • Bacterial pneumonia caused by Legionella pneumophila. • A type of pneumonia that affects the lungs and may also affect the stomach and intestines, kidneys, and central nervous system. • Incubation period: 2-10 days after exposure • Frequently requires hospitalization • Aerosol exposure from contaminated cooling towers, evaporative condensers, whirlpools, shower heads, faucets, & hot water tanks. Legionnaire’s Disease and Pontiac Fever

15. When inhaled, aerosol particles derived from aqueous fluids pick up moisture (water) while traveling in the respiratory passageways, thereby increasing in size. • Increased size changes deposition site H2O H2O H2O Hydroscopicity and Aerosol Deposition in the Respiratory Tract

16. Viruses: influenza, measles (rubeola), chickenpox (herpes varicella‑zoster) and rhinoviruses (colds); Hantavirus (from a rodent; mouse) Bacteria:Legionella spp., tuberculosis and other mycobacteria (Mycobacterium spp.), anthrax (Bacillus anthracis), and brucellosis (Brucella spp.). Fungi: diseases: histoplasmosis, cryptococcosis, blastomycosis, coccidiodomycosis, and aspergillosis Protozoans: Pneumocystiscarinii pneumonia; prevalent in immunodeficient hosts such as AIDS patients. Acanthamoeba encephalitis; primary amebic meningoencephalitis (PAM) Agents of Respiratory Infectious Diseases

17. Reservoirs: sources of air microbes Wide range, overall Depends on the microbe • humans, • animal, • soil • dust • water • air Reservoirs of Airborne Microbes

18. Viruses: • Mostly humans but some animals • Some rodent viruses are significant: ex: Lassa Fever Virus and Hantavirus. Bacteria: • Humans (TB & staphylococci), • other animals (brucella and anthrax), • water (Legionella) • soil (clostridia). Fungi: • soil and birds (Cryptococcus and Histoplasma) • dead plant material • wet surfaces (wood and other building materials) • indoor air (mycotic air pollution) • stagnant water for the opportunistic fungi (e.g., Aspergillus sp.). Airborne Microbes and their Reservoirs

19. Amplifiers: • Places where microorganisms multiply or proliferate. • Most reservoirs are potential amplifiers Amplifiers of air microbes

20. Devices causing microbes to enter airborne state or be aerosolized; often the reservoir or amplifier. • Any device able to produce droplets and aerosols: • Humans and other animals: coughs and sneezes, esp. • Mechanical ventilation systems • Nebulizers and vaporizers • Toilets (by flushing) Disseminators

21. Showers, whirlpools baths, Jacuzzi, etc. • Wet or moist, colonized surfaces (wet walls and other structures in buildings) • Environments that are dry and from which small particles can become airborne by scouring or other mechanisms: • Vacuuming or walking on carpets and rugs • Excavation of contaminated soil • Demolition of buildings Disseminators

22. Factors Influencing Airborne Infection

23. Particle size; <5 um dia.; "droplet nuclei" from coughing & sneezing • Deposition site: depends on particle size and hygroscopicity • Chemical composition of the aerosol particle • Relative humidity (RH); dessication (loss of moisture) • Temperature: generally greater inactivation at higher temperature Factors Influencing Airborne InfectionAerosol Factors

24. Sunlight: UV inactivation of microbes • Factors influencing air movement: winds, currents, mechanical air handlers, etc. • Seasonal factors: precipitation, air currents, pollen sources, etc. • Air pollution: • chemicals inactivating airborne microbes (OAF= Open Air Factor) • enhancing their ability to cause infection in a host

25. Size of microbe and of aerosol particle • influences air transport • influences deposition site: in environment and in host • Composition: • lipids, proteins (structural, enzymes), amino acids, etc. • enveloped and non-enveloped viruses respond differently to air pollution • Protective forms: • spores • cysts • growth phase • moisture content Microbe Factors:

26. Discussed previously in this class. Host Factors

27. Sampling the air microbes

28. Active sampling methods • Passive sampling method

29. Sedimentation methods: collection of aerosol particles on a sticky surface; e.g., a petri dish containing agar or glycerol. • Slit samplers: Sampled of air is directed through a slit against a rotating collection surface. For bacteria, this could be an agar medium petri plate. Rotation is intermittent so that each impaction area represents a specific volume of sampled air and a time series of samples can be collected. Air Samplers - Sedimentation and Slit Samplers Sedimentation - Agar Medium Plate Slit Sampler

30. Six stages, each a perforated plate located above a petri dish. • Diameter of air passageway is smaller at each successive level, collecting progressively smaller particles. • Classifies and collects particles according to size • Used mostly for bacteria. • Can be used for virus sampling by collecting onto a sticky surface in the petri dish. Air Samplers - Stacked Sieve (Anderson type) Sampler

31. Pass air through a membrane filter of small enough pore size to trap aerosol particles. • After collection, the filter can be plated or particles can be washed off. • Dessication and inefficient washing/recovery of collected particles can be problems. Open Face Air Filter Cassette with Cap Air Sampling - Filtration Methods

32. Air is drawn over electrically charged collection plates so that charged particles are attracted to and collected on either a positively or negatively charged, wetted surface. • Collected particles are washed off into the circulating collection fluid on the charged plate surface. Air Samplers - Electrostatic Precipitation

33. Collects particles from sampled air into a liquid medium. • All glass impinger (AGI). • Particles are drawn through a small orifice that increases their velocity, thereby causing them to impinge on the bottom surface of the container and be "scrubbed" into the collection fluid. • Excessive cooling and evaporation and leakage (particles not being retained) can be a problem. Air Samplers - Liquid Impingers

34. High volume liquid (cyclone) scrubber: Particles in air traveling at high speeds through a progressively smaller, helical passageway impinge against the container walls and are collected into a recirculating collection fluid supplied by a pump Air Samplers