The Coming Influenza Pandemic?

1 Comments:

At 6:23 PM,  Wulfgang said...

Orange;

Your first very first comment in today’s blog (“deaths and cases popping up all over… probable normal winter occurrence, but who knows”) and your last article about Ontario’s lack of preparedness five years after SARS, gives plenty of reason to step back and start looking at the big picture of influenza epidemics and pandemics, and what history is telling us about the risk we are facing. History does repeat itself and is an excellent predictor of “risk and reoccurrence”, when it comes to deadly diseases.

Currently, without any argument, H5N1 remains difficult for people to catch. The only hitch preventing a pandemic that I can see is the virus cannot cause sustained and efficient human-to-human infection. Nobody knows when this will occur, but history does clearly indicate pandemics and plagues have occurred regularly and frequently since recorded time, and the state of medicine and health during those same time periods had very little impact on suppressing them. For example:

Plagues:

• 430 BC Peloponnesian War – Typhoid fever killed one quarter of the worlds population

• 165-189 Antonine Plague – smallpox ¼ the population, and an estimated 5 million people (5,000 a day were dying in Rome according to historians)

• 541-750 Plague of Justonian – bubonic plague killed ½ of the known world and 10,000 per day at its height

• 1300’s Black Death – bubonic plague again killed 1/3-1/2 of the worlds population

• 1600-1800 Measles and Smallpox – killed 90-95 percent of all Native Americans and Mexican Natives

• 1816-1966 Cholera –8 epidemics and pandemics killed millions of people throughout the world

Influenza:

• 1510 – the worlds first pandemic killed unknown millions of people

• 1889-1890 Asiatic Flu (H2N8) kills many millions of people

• 1918-1919 Spanish Flu (H1N1) killed 55-90 million of the worlds population

• 1957-1958 Asian Flu (H2N2) killed 1 and ½ million people

• 1918-1969 Hong Kong Flu (H3N2) killed 1 million people.

Influenza pandemics typically come in waves and there have been about 3 influenza pandemics in each century for the last 300 years. The Asiatic and Spanish influenza pandemics each came in three or four waves of increasing lethality, but within each wave, mortality was greater at the beginning of each wave. The most likely candidate for the next pandemic, is either H5N1, H7N1 and H9N2. The only known influenza types currently circulating in humans, however, is H1N1, H1N2 and H3N2. Because of its increasingly large number of host reservoirs, and significant rapid mutations, the H5N1 virus clearly represents the largest threat since it has shown tendencies to be far more lethal than any known predecessor flu strain on record. The next and final phase of H5N1 only appears to be easy person-to-person transmission, and if that occurs, all known intervention measures will have to be used – and how effective they will be is anybody’s guess. (Resistance to current antivirals is already soaring).

What is especially disconcerting about the likelihood of worldwide influenza pandemic, and what the news articles are telling us, that you blog everyday, is the following:

(1) There are two circulating clades of H5N1 in circulation: clade 1 from Vietnam, and clade 2 circulating in Indonesia; both are antigenically different from each other; the vaccine of one would most likely not protect against a pandemic caused by the other.

(2) Countries with vaccine-manufacturing capability will reserve production to protect their own populations first and foremost; and will not release vaccines to other countries until their own populations are protected (the Supari argument, which has some basis)

(3) The area composed of China, Indonesia, India, Bangladesh, Pakistan, Vietnam, Tibet, Thailand, is the most likely epicenter and breeding ground of viruses for the next influenza pandemic, based on their population density and proximity to innumerable biological hosts and vectors (both mechanical and biological). The WHO and scientists around the world are focused too much on the total cumulative and annual human fatality data (which appears flat, year-to-year), and are not paying close enough attention to the tremendous and pervasive geographical spread of the virus and where it is becoming concentrated (super saturated).

(4) Polymerase Chain Reaction (PCR) diagnostic tests are proving to be unreliable, because significant proliferation of the viruses do not occur enough to detect their presence, or last of sensitivity. Arguable, but I believe we are seeing this repeated, time and again and this phenomena has corrupted the WHO data being reported and distorted test results (Niman argument, which has some basis).

(5) Transmission of the H5N1 viruses most likely are already coming from multi-sources: aerosolized droplets (not proven yet but it will be), ingesting contaminated food and water, bodily fluids, and contact with all types of fomites.

(6) The H5N1 virus has been co-evolving with its poultry hosts, but cannot quite yet achieve sustained and efficient human-to-human transmission. What is really quite concerning is that for Type A viruses there are 16 different HA antigens and 9 different NA antigens. Any one of them can re-combine with each other (including H5N1), creating a new variant which can become a novel pandemic strain. H5N1 is only a very few antigenic shifts or drift mutations away from becoming a human flu virus. The larger the number of possible hosts and co-infections occur, and the longer the “opportunities to mutate” are available in these densely populated countries, then this results in a theoretical unquantifiable increased risk and the greater the likelihood a pandemic will actually occur. This is what history tells us about close co-habitation with animals and their diseases, over the last two thousand years. What has changed to make this different in 2008 ? Nothing.

I believe that the history of influenza pandemics also is telling us is the following: if H5N1 mutates and becomes as transmissible as the common cold or other seasonal flu viruses, the results during the 21st century could be catastrophic, or at minimum, disastrous. Even though it most likely will give up some of its virulence in the process, I truly believe it could result in huge social and economic disruptions across the entire globe, mostly in these under-developed countries whose daily life lines are directly tied to poultry and swine production.

“Human deaths and cases popping up all over”… your words could well be the preface to the history book that describes the months leading up to the next great influenza pandemic.

Wulfgang

 

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