Not Your Father’s Influenza
#198



This past week, a major report was issued by the WHO (World Health Organization) on Avian Influenza, which presents the combined thinking of 22 scientists who met for three days in Geneva, Switzerland this past September.


The major headline to come out of this report was the emergence over the past year of a new, dominant strain of the H5N1 virus, the so called Fujian-like strain, that is rapidly replacing the older strains in China.


Lost in all of this reportage, however, is a somber description of why the Avian flu is so deadly, compared to other influenzas. Here is their summary assessment:


The disease caused in humans by the H5N1 virus was described as fundamentally different from that caused by normal influenza. In H5N1 infection, the disease syndrome typically shows progressive primary viral pneumonia, acute respiratory distress, marked leukopenia and lymphopenia, and (in some cases) diarrhoea and liver or renal dysfunction. What might explain this severity?

Some limited findings suggest that the virus might cause disseminated infection, affecting multiple organs. In some patients with a fatal outcome, virus has been detected in faeces, serum, and blood plasma. However, respiratory pathology remains the primary cause of death.

Additional data presented support the hypothesis that severe disease is based on induction of a “cytokine storm”; it was pointed out, however, that this remains a “chicken-and-egg” dilemma – does an overwhelming level of cytokinemia result in, or from, extensive tissue damage and disease?

http://tinyurl.com/yypcer

Undoubtedly, for some of my readers the medical jargon might be a bit unfamiliar, so allow me to translate.


In a normal case of seasonal flu, the virus enters the lungs, takes up residence for 5 to 7 days, and the body quickly fights off the infection. Rarely, and generally only in elderly, or immune compromised patients, viral pneumonia, or a secondary bacterial pneumonia may develop.


While seasonal flu kills an estimated 36,000 Americans each year, the flu is generally perceived as more of an inconvenience than a life threatening infection for healthy adults and children.


The H5N1 virus is different. First, it seems to stray beyond the lungs, and has been observed attacking multiple organs. The live virus has been detected in the bloodstream, something that is almost unheard of for seasonal flu. And it invokes a dramatic, and often deadly response from the host.


Instead of being rare, viral pneumonia occurs frequently. Acute Respiratory Distress (ARDS) commonly occurs. The body’s defense systems, its white cell (Leukocytes) counts and lymphocytes (killer cells) are severely depressed. Furthermore, the H5N1 virus seems to induce the so-called Cytokine Storm, a poorly understood phenomenon where the body’s defenses, rallying to fight off the infection, end up killing the patient by flooding the lungs with fluids and attacking the internal organs.


This Cytokine Storm is most pronounced in patients with the healthiest immune systems; in other words, those between the ages of 10 and 40. While the H5N1 virus can be deadly to people of any age, it has thus far proven to be a highly efficient killer of teenagers and young adults.


While H5N1 is indeed an influenza virus, calling it the `flu’ is like calling a Hurricane a patch of bad weather.


It doesn’t even begin to describe it.


So far, very little patient data has been publicly released. We know that roughly 60% of those diagnosed with the H5N1 virus have died. Of those that survived, most required weeks of hospitalization. We’ve heard that Tamiflu has been routinely administered, and that often patients have required ventilatory support. Presumably, other treatments are being tried: anti-inflamatories or steroids, antibiotics for secondary bacterial infections, even statins. But if they are, we aren’t hearing about it.


Thus far, the details of treatment, and the responses to different therapies, have been (to put it kindly) vague. Due to cultural preferences, autopsies are rarely performed, and so we have very little direct knowledge of how the disease kills its host.


The gaps in our knowledge regarding nearly every facet of the H5N1 virus continues to worry flu watchers around the world. Despite our advanced science, we still have too many unanswered questions.


But despite these black holes of data, one thing is obvious.


This isn’t just the flu.


Not by a long shot.