Showing posts with label respiratory infections. Show all posts
Showing posts with label respiratory infections. Show all posts

Saturday, October 10, 2015

Current Treatment of Respiratory Viruses - More Homilies






With Permission: SIB Swiss Institute of Bioinformatics,

Philippe Le Mercier, ViralZone.


My Facebook feed got me going today.  I get the Mayo Clinic feed since I consider their clinical care and some of their research to be the best in the world.  Of course social media is much less rigorous and sometimes it comes down to just advertising and promotion.  That was my assessment of the link to this document this morning.  It is a business document that purports to give advice on how to decrease your chances of a respiratory infection this winter.  Some of that advice is given by a Mayo Clinic Infectious Disease specialist and a Cleveland Clinic family physician.  There was one number I had not seen before and that is the Number Needed to Treat (NNT) for the flu vaccine is 40.  Forty people need to be vaccinated to prevent one case.  The advice is the usual set of homilies about respiratory infections including get the flu vaccination, wash your hands, sneeze into your sleeve, take care of yourself and stay home of you are sick.  In other words, there is no way in hell that you are not going to get sick at least once this winter.

Our continued 1950's approach to viral infections remains a mystery to me.  Certainly there are technical problems with trying to design vaccines for over 200 viruses that can cause the common cold.  But the reality is, vaccine design for influenza virus - easily the most lethal of these viruses is obviously not so hot.  As far as I know, vaccines for the most common of the cold viruses - Rhinovirus - is non-existent.  Anti-viral medications for respiratory viruses are more controversial.  Looking at the most popular one Tamiflu or oseltamivir.  The NNT to prevent one death may be 1,800 - 3,200.  The NNT to prevent one hospitalization may be 97 to 142 depending on criteria.  The NNT group suggests somewhat better NNTs of 36 and 83 for preventing a culture positive case of influenza and preventing pneumonia respectively.    Contrast that with the NNT for antidepressants of 5-10 as determined by Leucht, et al (2) in their comparison to other medications for various medical conditions.  And you thought antidepressants were ineffective?

Infectious disease respiratory virus research is a goldmine for all of the Luddites out there.  There are a number of web sites that provide free access to just about everything you ever wanted to know about every virus known to man.  The viral particle shown at the top of this page is the order that contains Rhinoviruses one of many common cold viruses and one of the viruses that may be responsible for the expression of asthma in predisposed individuals or exacerbations of asthma in asthmatics who are asymptomatic.   This illustration is from the ViralZone, one of many free online databases with detailed information about the molecular biology and genetics of viruses.  If I was an aspiring Luddite wanting to be provocative about the field of medicine being stuck in the 1950s despite the availability of all of this advanced information - this would be a logical place to start.

In previous posts here I have also critiqued the lack of attention given to environmental approaches to respiratory viruses and the fact that the airborne nature of some of these viruses is not acknowledged - possible because airborne viruses are not contained by hand washing and other direct contact techniques.  It s well know that viruses can be collected in the heating and air conditioning systems of public buildings and that altering the humidity and air flow characteristics in those buildings can change the viral concentrations in the air.  Whenever I have mentioned this to the administrators of buildings where repeated respiratory epidemics swept through the staff - I got the same response that I received from an airline after I reported a severe respiratory infection after one of their flights: "We are really sorry that you had flu-like symptoms after your flight and look forward to your future comments to help us improve our service."

What?!

 Time to get serious about respiratory infections and come up with some effective interventions.  Effective medication to prevent viral replication and spread in the infected and to create barriers to infection would be ideal and so would environmental methods to reduce the infection rate.  Considering the strong incentives in America to work while sick and considering that the average worker is going to get 2 to 3 respiratory infections per year that can last up to 3 weeks in duration means that very few of us and the patients that we treat are not going to be exposed and infected.  With the current advanced knowledge of the pathogens and modern heating and air conditioning systems it seems like a lot more could be done right now.


George Dawson, MD, DFAPA


References:

1:  Postma MJ.  Re: Tamiflu: NNT to prevent a pandemic flu death may be a million.  BMJ 2005; 331:1203.

2:  Leucht S, Hierl S, Kissling W, Dold M, Davis JM. Putting the efficacy of psychiatric and general medicine medication into perspective: review of meta-analyses. Br J Psychiatry. 2012 Feb;200(2):97-106. doi: 10.1192/bjp.bp.111.096594. Review. PubMed PMID: 22297588.


Attributions:

Graphic at the top of this post is courtesy of: SIB Swiss Institute of Bioinformatics, Philippe Le Mercier, ViralZone.  http://viralzone.expasy.org/  licensed via Creative Commons Attribution- NonCommercial 4.0 International License.

Monday, August 17, 2015

Is It Time To Quarantine Air Travelers?



My wife and I just got back from Alaska on August 10, 2015 and within a few days became progressively symptomatic with an influenza-like illness that appears to be peaking today on day 5.  I know exactly how we were infected.  There were several ill passengers, particularly in close proximity who had not mastered coughing into the crook of the arm and who were actually coughing and sneezing over the top of the arm.  The plane was packed as usual.  We had paid an extra $100 to be able to sit in "economy comfort class".  In fairness there was about an extra 4 inches between my knees and the back of the seat in front of me (and I m 5'10'' on a good day).  Even that could not make up for the severe ergonomic problems of airplane seating.  I would quickly describe those as a lack of upright, even in the upright position.  Upright is at least 15-20 degrees from upright and over the course of a 5 hour flight that can create quite a bit of pain in anyone with a back problem.  This problem has been studied to some extent as evidenced by bullet point 3 on this web page.  The economy comfort class also comes with free alcoholic beverages, and I saw one passenger who was clearly uncomfortable rapidly down 4 drinks.  The other ergonomic problem is an ill defined seat.  It felt like sitting on 5 or 6 tennis balls all the way.

But back to the focus on viruses.  From discussing the problem with friends and family it is almost a universal experience that people get viral illnesses on their flight back from a recreational or work destination.

When I boarded a cruise ship recently I was screened for GI symptoms and asked if I had any recent illnesses as part of the check-in procedure.  That did not happen at any point when I got on either of the direct flight to or from Minneapolis.  In addition to the screening procedures there was hand sanitizer being actively and passively dispensed throughout the ship and on the ships TV channel the following message played continuously on a 24/7 basis:

Please wash your hands often and use the sanitizer stations provided throughout the ship especially when you are coming from ashore.  Always use a fresh cup when using beverage dispensers and refrain from using personal containers directly or on common beverage stations.  To stay healthy wash your hands with soap and warm water frequently.

 In comparing respiratory infections from air travel to Norovirus infections on cruise ships there are important differences.  The Norovirus infections occur in a well defined captive population in  very specific time period.  If an outbreak occurs it can become widely known, to the public relations detriment of that cruise line.  If a respiratory virus is contracted on a flight, everyone leaves the plane after arrival in a few hours and the total number of people infected is unknown.  There have been studies that look at the attack rates of people who have been on a flight where there is an index case of influenza and also the effects of using masks prophylactically when there are known index cases onboard.  There are no cautions to the passengers about how to prevent the spread of respiratory infections and (to my knowledge) no easy way for them to cancel in the event that they develop an acute upper respiratory in infection.  The CDC has some limited guidance on air travel, including some information on influenza transmission cabin air conditioning including the fact that it is partially recirculated and HEPA filtered 15-20 times per hour.  The most interesting study in microbial diversity in commercial aircraft that I could find was by Osman, et al (1) who compared conventional culture techniques to available molecular probes in 2008 in samples from 16 domestic and international flights.  They conclude that the molecular probe techniques demonstrated a much greater microbial diversity than culture techniques and that microbes varied significantly from domestic to international flights.  The molecular probe techniques identified 12 classes and 100 species of bacteria in cabin air, but in sufficiently low concentrations to not present a health hazard.  I am aware of studies in the past that have done viral cultures for respiratory viruses on filters in buildings but could not find similar data for commercial aircraft.  There have already been simulations about what happens when a person sneezes on an commercial aircraft, and those results are eye-opening.  I posted that in a look at the issue of hand washing and respiratory viruses.

Rather than go into excessive detail about the limited research that has been done so far, let me summarize a few facts and my conclusions.  Respiratory viruses can be transmitted during commercial air travel.  The attack rate for influenza virus has been estimated to be 2 - 4%.  There has been at least one study that shows masks can prevent infection.  There have been several simulations of how air travel potentially increases the world wide spread of airborne viral infections and some of these infections like corona virus and SARS outbreaks puts a significant burden on the international public health community.  Furthermore, the public health burden in terms of both morbidity and mortality is huge.  Influenza virus alone kills about 20,000 people annually in the United States or the equivalent of 5 large cruise ships in terms of total lives.  By comparison, there if far more press coverage of a Norovirus outbreak on a cruise ship and that virus is much less fatal.  Every American contracts about 2 - 3 respiratory viruses per year of varying severity.  That probably amounts to about 2-6 weeks of illness per year, associated with a disruption of work and daily activities as well as increased infection risk for those in the sphere of that person's routine.  There is also a risk for exacerbation of chronic illnesses like asthma and chronic obstructive pulmonary disease.

All of these considerations lead me to suggest (at the minimum) - the following measures:

1.  Intensification of study of airborne diseases especially respiratory viruses:  The technology is certainly there and there is no reason that molecular technologies cannot be applied to samples from commercial aircraft and I think that the HEPA filters are a logical place to start.  I would really like to see this become a focus of a private research fund, because it seems like the federal government has created numerous monitoring systems but no practical ways to detect high risk scenarios and disrupt disease transmission.  It seems like that is likely to occur only after an outbreak of a highly fatal respiratory virus occurs.

2.  Passenger education is critical:  The airline industry needs to adopt the methodologies that are currently employed in the cruise industry - educating everyone on the plane, screening for passengers at risk and quarantining them if necessary.  A critical piece of the education process is that while hand washing is necessary, it is not sufficient to prevent the spread of airborne respiratory viruses.  That public needs more awareness of that concept and what else can be done.  The method of quarantine is debatable and would probably need some flexibility based on passenger needs and acceptability and the severity of the problem.  It could include grounding until the infection clears, use of masks to block airborne infection, or possibly a section of the passenger cabin with more intensive HEPA filtering (altering air flow and humidity can affect the likelihood of virus transmission).

3.  Developing a culture to reduce the risk of respiratory virus infection:  Everywhere that I look we have practices in place that encourage the transmission of respiratory viruses.  Most Americans do not let respiratory viruses stop them from carrying on their business as usual.  In the past few days, I have personally walked through clouds of sneezed droplets because I happened to be following a fellow customer or coworker too closely at the wrong time.  I can't recall exactly when it happened, but getting rid of sick and vacation time and replacing it with paid time off or PTO days is an incentive for going to work sick.  Most of that sickness is respiratory viruses.

The American attitude to the common cold is far too casual.  It does not take into account the spectrum of symptom severity and the fact that many of these viruses can cause influenza-like illnesses and very severe syndromes.  Even a cold of moderate severity generally curtails a lot of activities and produces significant morbidity.  I don't understand how the medical and consumer community has come to this level of acceptance and denial of this collection of more-than-just-a-nuisance pathogens, but I would like to see it stop.

The American attitude toward the bad ergonomics of airline seating is another issue.  I think it is unfortunate that most passengers these days have never flown on a 747.  I may be overidealizing the flying of my youth, but planes today seem like dismal narrow aluminum tubes by comparison.



George Dawson, MD, DFAPA



References:

1: Osman S, La Duc MT, Dekas A, Newcombe D, Venkateswaran K. Microbial burden and diversity of commercial airline cabin air during short and long durations of travel. ISME J. 2008 May;2(5):482-97. doi: 10.1038/ismej.2008.11. Epub 2008 Feb 7. PubMed PMID: 18256704.

Supplementary 1:

For a graph of the URI I contracted on the Alaska vacation and most likely on the flight home follow this link.


Attribution:

The graphic at the top of the blog is directly from the CDC and one of their pages on Middle East Respiratory Virus Coronavirus.  Photographic credit is given to Jennifer L. Harcourt.  The picture depicts coronavirus particles in the cytoplasm of an infected cell.

Sunday, January 11, 2015

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 (10viral 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.