April 14, 2013


I'll admit to tracking recent reporting of H7N9 with a bit more interest than your average bear. I spent a year on a small team developing a national bio-surveillance program during the H5N1 "bird flu" scare not so many years ago. It was quite an educational experience in many ways but particularly with regard to the "drinking from a fire hose" learning necessary to rapidly come up to speed on some of the more interesting aspects of bio-threats, both naturally occurring and man-made. The team leader was brilliant in demanding that we read a masterful book by John M. Barry entitled "The Great Influenza: The Story of the Deadliest Pandemic in History." While the primary theme is the influenza pandemic of 1918 (causing upwards of 100 million deaths), Barry also tells the broader story of how the search for a cure -- in fact, the search to even understand what the flu virus was -- actually served as a catalyst for the birth of modern medical science and of the social impact the pandemic had across communities large and small, urban and rural.

The 'bird flu' scare of 2006 (actually 2003 to present but cases/deaths peaked 2005-07) likewise had an impact well beyond the actual number of cases of human infection, spurring lurid reporting in the news, the rise of a 'bird flu protection' industry, widespread community and municipal awareness and pandemic response preparedness programs, and even a made-for-tv-movie or two. Since the much-feared and over-hyped global pandemic never materialized as popularly imagined, most folks (I think) tend to dismiss the actual risk such outbreaks have inherent to them. The field of bio-surveillance has really improved over the past decade perhaps no where more importantly than in the areas of information reporting, sharing and preventive posturing, i.e. the willingness of government agencies and the medical community to collaborate in aggressively investigating and responding to the potential for outbreaks.

The current reporting on H7N9 indicates no cases of human-to-human transfer. As of today all 43 reported cases of infection have occurred from close contact with infected birds. For those interested in reading up on the outbreak, the World Health Organization site is pretty informative and is kept up-to-date with each reported and confirmed case: WHO H7N9. For information on influenza in general and the H5N1 strain especially, the flu.gov site is really very good. A companion site - ready.gov - is also a good resource for information on emergency preparedness planning.

An addendum:  The medical and biosurveillance/response communities are consumed with analytics of all sorts -- massive data sets compiled by doctors, medical institutions and various agencies/organizations at the local, state, national and international levels; models based on available data and patterns of transmission, human behavior, viral mutations, etc.; and field research to collect and test samples and report results back to the lab-based medical community. All these efforts are used to understand patterns and connections between reported events such as bird die-offs or spikes in reporting of relevant symptoms. An item of interest with H7N9 is that previously it seems that humans weren't susceptible to infection. Given that human infections are now being reported some sort of mutation has occurred with this particular influenza strain -- not unusual of course because mutations occur all the time (hence the need to tweak flu vaccines every year). (As an aside, a Chinese official has accused the US of biowarfare; the US supposed foisting this problem on the Chinese. Gimme a break.)

Human-to-human transmission of the flu occurs when an infected person coughs, the flu-virus is expelled in the tiny droplets projected from the lungs (where the virus has taken up residence), and another person breaths in the droplets. For this to happen, the virus must be resilient enough to remain viable during the transmission process and it must live high enough in the lungs so that it can be expelled with a cough. Also, it can't be too lethal otherwise the infected population dies off too quickly, thus bringing an epidemic to a quick close. (A really bad influenza outbreak would have a lethality in the 10-15% range.)

Currently, when someone is diagnosed with the flu, that case is logged in a database (or several) and the accumulating info is analyzed for type, frequency, virulency, location, spread, proximity to transportation corridors, manner of infection and transmission, etc., etc., etc. For a disease to present a really high threat to humans, a great many factors have to come together all at the same time. That rarely occurs but when it does the impact can be extraordinary. In 1918, the influenza strain was one to which people had not previously been exposed and therefore had no resistance to. The outbreak also occurred during the US mobilization for entry into WWI so we had camps of young soldiers all packed together in close quarters. As the soldiers were moved to join the war effort in Europe, they were transported to East Coast ports (like New York, Boston, Philadelphia) by train and packed trucks/buses, then crammed together aboard troop ships. This enabled rapid transmission of a virus, for which no one had immunity, among the masses of troops confined in close quarters and enabled its spread to Europe and then around the world.

With this background in mind, today's flu-watchers try to account for all these factors and conditions, enabled by diagnostic advances and revolutionary advances in communications and the related ability to share information.

Oh...the best protection? All the simple actions you've known since childhood -- cover your mouth when you cough, wash your hands, stay home from work when you don't feel well, eat a balanced diet, and keep saltine crackers and chicken soup stocked in the cupboard! There, don't you feel better now?

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