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TB and the Rheology of sputum: alcohol, tobacco smoking, and crowded bars

By jayanth devasundaram | 04 Feb, 2009

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?



Edward Nardell, MD Moderator Replied at 7:11 AM, 4 Feb 2009

Kevin Fennelly at New Jersey College of Medicine and Dentistry is
interested in sputum viscosity and other physical properties as a factor
in "source strength". I am hoping he will respond. Generally, as you
probably know, less viscous sputum is thought to be easier to
aerosolize. It is an interesting thought about alcohol, but I doubt
there is research on that. My impression as a pulmonologist is that
there are really no good expectorants out there, even among agents
intended to improve sputum clearance. Moreover, ability to raise sputum
and clear airways and ability to aerosolize are probably two different

There are many other reasons why bars are good places for TB
transmission. There may be socioeconomic selection for people with TB,
the effects of alcohol on treatment adherence, effects of alcohol on
lung macrophages, and of course, crowding. Cigarette smoking, not rare
in bars except in the US, is now recognized as important risk factor in
TB transmission.

A company here in Massachusetts, Pulmatrix, is investigating the
potential of simple inhaled salt solutions to mitigate aerosol
production. These have been shown to be effective in reducing particle
production of all sizes, but especially those produced during quite
breathing in the nanoparticle range. The relevance of these findings to
TB transmission is unknown, but effects on transmission of other
organisms have been demonstrated. Please see the PNAS article by
Professor David Edwards (I was fortunate to be a co-author) which I will
ask the GHDonline staff to post.


Dr. Edward A. Nardell
Associate Professor
Harvard Medical School (Medicine; Global Health and Social Medicine)
Harvard School of Public Health (Environmental Health; Immunology and
Infectious Diseases)

Brigham and Women's Hospital
Division of Global Health Equity
FXB Building, 709c
651 Huntington Ave.
Boston, MA 02115

Kevin Fennelly, MD Replied at 8:41 AM, 6 Feb 2009

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 Fennelly, MD, MPH
Interim Director
Division of Pulmonary & Critical Care Medicine
New Jersey Medical School-UMDNJ
150 Bergen Street, UH-I 354
Newark, NJ 07101-1709

Becky Peters Replied at 4:42 PM, 13 Feb 2009


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 Peters

Christian Auer Replied at 3:28 PM, 14 Feb 2009

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*)

Edward Nardell, MD Moderator Replied at 12:21 AM, 15 Feb 2009

A doctoral student at Harvard School of public health, Hsien-Ho Lin, who
has been studying the association of smoking and TB, offers the
following comment and two references which I will post on the GHDonline


Hi Ed,

Many thanks for the email. I would suggest two meta-analyses on the
association between smoking and TB:

1. Bates MN, Khalakdina A, Pai M, Chang L, Lessa F, Smith KR. Risk of
tuberculosis from exposure to tobacco smoke: a systematic review and
meta-analysis. Arch Intern Med 2007; 167: 335-42.

2. Lin HH, Ezzati M, Murray M. Tobacco smoke, indoor air pollution and
tuberculosis: a systematic review and meta-analysis. PLoS Med 2007; 4:
e20. (available at:

Both reviews found that smoking is associated with an increased risk for
TB disease (relative risk around 2~3). Smoking is also possibly
associated with an increased risk of latent TB infection, although the
evidence is not as strong as that for smoking and TB disease.

Please let me know if you need more references.

Thank you!!


Vishnu Kamineni Replied at 9:22 PM, 15 Feb 2009

Dear Dr Rana,

Hope you are well. Many thanks for sharing this interesting reference.


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