Hand Washing

I washed my hands 40 times yesterday and used disinfectant hand cleaner at least 10 times when I did not have immediate access to water and soap.   My hand washing technique was validated by  an infection control nurse who was trained to monitor appropriate hand washing.   I also wiped down the table in my office and the chair about 3 times with disinfectant wipes.  I am careful not to touch my food or my face.  I have an air cleaner running in that office from about 8AM to 6PM that has a UV lamp designed to kill viruses.  Despite all of that I am in day #5 of a flu-like illness (cough, myalgias, fatigue, but no fever).

I don't have obsessive compulsive disorder.  I live in Minnesota and it is peak season for the annual influenza epidemic.  I actually take more precautions.  During flu season, I avoid the public.  I used to belong to a gym, but set up my basement so I could do my workout routine at home.  Exercise equipment is a known reservoir of viruses and bacteria.  I have also been in a gym when it sounded more like a hospital ward due to the hacking and coughing.  I avoid movie theaters for the same reason.  I have been doing these same rituals for the past twenty years, initially because I thought I was allergic to influenza vaccine and did not want to catch the flu.  I have been fairly  successful in avoiding the flu, but not so successful in avoiding practically every other respiratory virus.  For twenty three years I worked in an old building that was designed to contain heat rather than clear respiratory viruses.  In that environment, once a virus is introduced there is a predictable epidemic (sometimes within a few days) affecting the entire staff.   Modern employment disincentives (the finite paid time off with no sick time system) keeps all of the ill people working.  They would rather work than lose vacation time.  That keeps the epidemic going.

 Throughout the flu season people at risk are told the same things.  Wash your hands, cough into your sleeve, stay at home if your are ill and get the flu shot.  Unfortunately all of these measures is not enough to prevent infection by airborne viruses.  Face masks help.  A study of college dormitory dwellers showed that hand washing and wearing a mask only offered modest protection against influenza like illness relative to a control group.  They used the term modest, but I would call about a 10% difference in infection rates weak at best.  In their study they looked at three groups of students in college dormitories.  The groups and the attack rates of flu-like illness (FLI) included controls (no intervention) 117/552, face mask only 99/378, and face mask and hand hygiene 92/367.   The authors tried to control as many measures as possible but there are a lot of reasons why experimenting on college students is problematic.  In terms of the basic methods hand washing or use of hand disinfectants is considered to have a small but significant effect on the transmission of respiratory viruses.  The effectiveness of masks depends on the fit of the mask, the physical characteristics of the environment and the virus itself.  One study (4) showed that a tightly sealed N95 respiratory mask would block 94.8% of influenza virus and a poorly fitting mask blocked only 56.6% of the virus.  

The process of creating infectious droplets is an interesting physical process.  There are  current estimates that show normal breathing for 5 minutes creates a few droplets through the process of atomization.  A single strong nasal expiration results in a few hundreds droplets with a few in the 1-2 µm in diameter.  Counting loudly creates a few hundred droplets in the 1-2 µm range.  A single cough produces a few thousand and a single sneeze produces a few hundred thousands to a few million 1-2 µm droplets that can contain viral particles.  There is a a video of what happens to those millions of sneeze generated particle in an airplane.  It might be a good place to wear a mask but that assumes that you have it on before the sneeze.  Atomization can also occur from vomit (10⁷ viral particles per ml) and feces (10¹² viral particles per gram).   Those routes of transmission have been important for SARS and Norwalk Like Viruses.

The most recent estimate of costs due to building influenced communicable respiratory infections was about $10 billion in direct treatment costs and indirect costs of $19 billion in lost productivity and $3 billion in performance losses.  Asthma is significantly affected and possibly caused by airborne respiratory viruses and that is another $18 billion in costs ($10 billion direct and $8 billion indirect).  My interest has been in trying to promote more attention to the problem especially at the environmental levels.  Just altering airflow characteristics or making other changes in the humidity and air temperature can reduce the infectivity rates by as much as 50%.  Apart from the cost, it has an immeasurable effect on employee morale.  It is difficult for anyone to work knowing that at least one month out of the year they will have significant symptoms of a respiratory syndrome.

Why did I post this and in particular on a psychiatry blog?  In my 23 years of inpatient experience, respiratory viruses plagued the staff and the patients we were treating.  Any attempt I made to change that from a non-medical environmental perspective was met with no response.  I think that is the standard response of our culture and most employers.  Mental health settings tend to be located in older buildings and older parts of health care campuses and respiratory viruses is likely a bigger problem.  Health care settings should be leaders in developing environments and infrastructure that is hardened for the airborne respiratory virus problem.  It is imperative as a healthy environment for workers and patients and it provides reserve capacity in the event of a more widespread pandemic.  I have also made some observations about the impact of FLI on psychiatric symptomatology - both improvements and worsening.  There is a increasing literature on the effect of cytokine signaling on brain function and I suspect that is what I was seeing, but more research is needed.    

In the meantime, keep washing your hands.  Keep in mind that this post is only about airborne infections.  Any physician with direct contact with patients needs to wash their hands after seeing a patient and before seeing the next patient.  Most hospitals have a rule that hand washing needs to occur every time a physician enters or leaves a room.   For airborne respiratory viruses, it is not enough but it decreases the risk of respiratory infections to a slight degree.  My guess is that the more highly infectious airborne viruses are much less containable with hand washing and that environmental measures involving airflow, relative humidity, and possibly filtration and UV sterilization is what is required.  Anyone planning new construction should focus on these measures and obtain appropriate heating and air conditioning consultation with an emphasis on reducing respiratory infections.


George Dawson, MD, DFAPA

References:


1:  Aiello AE, Murray GF, Perez V, Coulborn RM, Davis BM, Uddin M, Shay DK,Waterman SH, Monto AS. Mask use, hand hygiene, and seasonal influenza-like illness among young adults: a randomized intervention trial. J Infect Dis. 2010 Feb 15;201(4):491-8. doi: 10.1086/650396. PubMed PMID: 20088690.

2: Verreault D, Moineau S, Duchaine C. Methods for sampling of airborne viruses. Microbiol Mol Biol Rev. 2008 Sep;72(3):413-44. doi: 10.1128/MMBR.00002-08. Review. PubMed PMID: 18772283; PubMed Central PMCID: PMC2546863.

3: Morawska L. Droplet fate in indoor environments, or can we prevent the spread of infection? Indoor Air. 2006 Oct;16(5):335-47. Review. PubMed PMID: 16948710.

4: Noti JD, Lindsley WG, Blachere FM, Cao G, Kashon ML, Thewlis RE, McMillen CM, King WP, Szalajda JV, Beezhold DH. Detection of infectious influenza virus in cough aerosols generated in a simulated patient examination room. Clin Infect Dis. 2012 Jun;54(11):1569-77. doi: 10.1093/cid/cis237. Epub 2012 Mar 29. PubMed PMID: 22460981.

5. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) ASHRAE Position Document on Airborne Infectious Diseases Approved by ASHRAE Board of Directors January 19, 2014 Expires January 19, 2017.  - This is an interesting approach that looks at how to look at engineering approaches to airborne infectious particles and come up with a better approach.

Supplementary 1:  Various inhalers used over the past year following a probable rhinovirus exacerbation of asthma in January of 2013.  This is a rapid way to meet your annual deductible.

Supplementary 2:  Graphic of pathogens detected per week is from the Minnesota Department of Health web site.