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Does anyone know of any work done to characterize the flow properties (rheology) of sputum as a factor in the spread of TB? Does the consumption of alcohol act as an expectorant and enhance the dissemination of TB in crowded bars?
Kevin Fennelly at New Jersey College of Medicine and Dentistry isinterested in sputum viscosity and other physical properties as a factorin "source strength". I am hoping he will respond. Generally, as youprobably know, less viscous sputum is thought to be easier toaerosolize. It is an interesting thought about alcohol, but I doubtthere is research on that. My impression as a pulmonologist is thatthere are really no good expectorants out there, even among agentsintended to improve sputum clearance. Moreover, ability to raise sputumand clear airways and ability to aerosolize are probably two differentthings. There are many other reasons why bars are good places for TBtransmission. There may be socioeconomic selection for people with TB,the effects of alcohol on treatment adherence, effects of alcohol onlung macrophages, and of course, crowding. Cigarette smoking, not rarein bars except in the US, is now recognized as important risk factor inTB transmission. A company here in Massachusetts, Pulmatrix, is investigating thepotential of simple inhaled salt solutions to mitigate aerosolproduction. These have been shown to be effective in reducing particleproduction of all sizes, but especially those produced during quitebreathing in the nanoparticle range. The relevance of these findings toTB transmission is unknown, but effects on transmission of otherorganisms have been demonstrated. Please see the PNAS article byProfessor David Edwards (I was fortunate to be a co-author) which I willask the GHDonline staff to post. EdDr. Edward A. NardellAssociate ProfessorHarvard Medical School (Medicine; Global Health and Social Medicine)Harvard School of Public Health (Environmental Health; Immunology andInfectious Diseases) Brigham and Women's HospitalDivision of Global Health EquityFXB Building, 709c651 Huntington Ave.Boston, MA 02115
Hi, Jayanth, Ed, et al, Ed is correct about the hypothesis that less viscous secretions are more likely to be aerosolized. It has been proposed for years (e.g., Bates and Stead), but I am not aware of data to support it. We have some supportive (unpublished) laboratory data using a laboratory model of cough-generated aerosols. Unless subjects are aspirating the alcohol, I doubt that it would be acting to change the rheology of secretions. I suspect that a far more potent factor in bars is smoking, laughing,talking and associated coughing.Hope this helps.Kevin Kevin Fennelly, MD, MPHInterim DirectorDivision of Pulmonary & Critical Care MedicineNew Jersey Medical School-UMDNJ150 Bergen Street, UH-I 354Newark, NJ 07101-1709
Hello,I've posted the article referenced by Dr. Nardell- "Inhaling to mitigate exhaled bioaerosols" by David Edwards et al., as a new resource: http://www.ghdonline.org/ic/resource/inhaling-to-mitigate-exhaled-bioaerosols/Hope this is helpful!Becky PetersGHDonline
Is it possible to get a reference or other source regarding the statement "Cigarette smoking is now recognized as important risk factor in TB transmission."What I found is the following:*A toxic gas present in air pollution and tobacco smoke plays a significant role in triggering tuberculosis infection, according to a new study from researchers at the University of Alabama at Birmingham (UAB). The study showed that CO triggers M. tuberculosis to shift from active infection to a drug-resistant dormant state. (*Ashwani Kumar et al *Heme Oxygenase-1-derived Carbon Monoxide Induces the Mycobacterium tuberculosisDormancy Regulon *, J. Biol. Chem., Jun 2008; 283: 18032 - 18039*)
A doctoral student at Harvard School of public health, Hsien-Ho Lin, whohas been studying the association of smoking and TB, offers thefollowing comment and two references which I will post on the GHDonlinewebsite. EdHi Ed,Many thanks for the email. I would suggest two meta-analyses on theassociation between smoking and TB:1. Bates MN, Khalakdina A, Pai M, Chang L, Lessa F, Smith KR. Risk oftuberculosis from exposure to tobacco smoke: a systematic review andmeta-analysis. Arch Intern Med 2007; 167: 335-42.2. Lin HH, Ezzati M, Murray M. Tobacco smoke, indoor air pollution andtuberculosis: a systematic review and meta-analysis. PLoS Med 2007; 4:e20. (available at:http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0040020)Both reviews found that smoking is associated with an increased risk forTB disease (relative risk around 2~3). Smoking is also possiblyassociated with an increased risk of latent TB infection, although theevidence is not as strong as that for smoking and TB disease.Please let me know if you need more references.Thank you!!Hsienho
Dear Dr Rana,Hope you are well. Many thanks for sharing this interesting reference.Vishnu
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