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Monday, October 28, 2013



An influenza pandemic can occur when a non-human (novel) influenza virus gains the ability for efficient and sustained human-to-human transmission and then spreads globally. Influenza viruses that have the potential to cause a pandemic are referred to as ‘influenza viruses with pandemic potential.

Examples of influenza viruses with pandemic potential include avian influenza A (H5N1) and avian influenza A (H7N9) which are two different “bird flu” viruses. These are non-human viruses (i.e., they are novel among humans and circulate in birds in parts of the world) so there is little to no immunity against these viruses among people. Human infections with these viruses have occurred rarely, but if either of these viruses was to change in such a way that it was able to infect humans easily and spread easily from person to person, an influenza pandemic could result.


So far, the spread of HPAI H5N1 virus from person-to-person has been very rare, limited, and not sustained. To date, there is no evidence of genetic reassortment between human influenza A viruses and HPAI H5N1 viruses. There has also been no indication that these viruses are becoming more transmissible to humans or from human to human. Even though HPAI H5N1 viruses are spreading among poultry and wild birds and this increases the possibility of human exposures to infected birds or poultry, it has not increased the ability of HPAI H5N1 viruses to infect and transmit between people. (Infection and transmission among people remains a rare event.)

Although highly pathogenic avian influenza (HPAI) A (H5N1) virus infection of humans is rare, sporadic cases of human infection have been reported.  More than 600 human HPAI H5N1 cases have been reported to WHO from 15 countries in Asia, Africa, the Pacific, Europe and the Near East since November 2003. Approximately 60% of the cases have died.  Indonesia, Vietnam and Egypt have reported the highest number of human HPAI H5N1 cases to date.  There have been 606 human cases overall since 2003 (approximately 10 years of monitoring).  

In other terms, that is about 60-61 cases per year, which equates to catching HPAI H5N1 at a rate of 1 out of 118,677,988.  To put this in numbers that make a bit more sense, the following is a list of some things that people often ponder:

               Type of Event                                       Chances of It Happening

  1.  Hitting Mega Millions Jackpot                         1 in 130,000,000
  2. AVIAN FLU / PANDEMIC FLU                           1 in 118,677, 988
  3. Getting Crushed by a Vending Machine            1 in 112,000,000
  4. Getting Attacked by a Shark                           1 in 11,500,000
  5. Getting Elected President of the US                 1 in 10,000,000
  6. Getting Hit by Falling Airplane Parts                1 in 10,000,000
  7. Getting Radiation Poisoned by Nuclear Plant    1 in 10,000,000
  8. Being Killed by Bees                                      1 in 6,100,000
  9. Being Killed by Poisonous Animal or Plant         1 in 3,500,000
  10. Becoming a Famous Movie Star                      1 in 1,500,000
  11. Getting Hit by Lightning                                 1 in 1,000,000 in any given year
  12. Drowning in Bathtub                                      1 in 840,000
  13. Dying from Heat / Sun Exposure                     1 in 11,111
  14. Getting Hit by Lightning (in your total life)       1 in 10,000
  15. Being in a Fatal Plane Crash                           1 in 7,229
  16. Killed from Falling Down / Out of Bed              1 in 258
  17. Killed in a Car Crash                                      1 in 108
  18. Dying from Heart Disease or Cancer               1 in 7

Now that some of the numbers are in perspective, there is a remote chance of catching Avian / Pandemic Flu... somewhere between hitting the Mega Millions Lottery and getting crushed by a random falling vending machine.  Which also means you are about 10 TIMES MORE LIKELY to be elected President of the United States, get struck by a random piece of space / plane debris or be involved in a Nuclear Plant Meltdown.  You are 100 TIMES MORE LIKELY to become a Hollywood Movie Star, 1000 TIMES MORE LIKELY to be struck by lightning or be involved in a fatal plane crash and ONE MILLION TIMES MORE LIKELY to die in a car crash than get Pandemic/ H5N1 Influenza.

Avian Influenza A (H7N9) Virus 

An outbreak of human infections with a new avian influenza A (H7N9) virus was first reported in China by the World Health Organization on April 1, 2013. The virus was detected in poultry in China as well. During the outbreak, more than 130 human infections with H7N9 were reported, the vast majority during the month of April. Many of the people infected with H7N9 reported contact with poultry.

The working assumption is that human infections occurred after exposure to infected poultry or contaminated environments. While some mild illness in human cases was seen, most patients had severe respiratory illness and 44 people have died. Close contacts of confirmed H7N9 patients were followed to determine whether any human-to-human spread of H7N9 was occurring. No evidence of sustained person-to-person spread of the H7N9 virus was found. No cases of H7N9 outside of China have been reported and the new H7N9 virus has not been detected in people or birds in the United States.

The number of cases detected after April fell abruptly. The decrease in the number of new human H7N9 cases may have resulted from containment measures taken by Chinese authorities, including closing live bird markets, or from a change in seasons, or a possibly a combination of both factors. Studies indicate that avian influenza viruses have a seasonal pattern to them, much like human seasonal influenza viruses. If this is the case, H7N9 infections – in birds and people – may pick up again when the weather turns cooler in China.

Limited person-to-person spread of bird flu is thought to have occurred rarely in the past, most notably with avian influenza A (H5N1). Based on this previous experience, some limited human-to-human spread of this H7N9 virus would not be surprising if the virus reemerges in the fall.  


Clearly, there is some risk and it is certainly prudent to monitor each strain of Avian / Pandemic Influenza as genetic mutations can easily occur which MAY produce a strain that is highly virulent as well as having a high rate of morbidity / mortality.  However, at the current time, all major organizations and centers around the world are reporting low levels of any pandemic influenza strains, and in fact, the pandemic concerns that first surfaced in 2003 have been very slow to transfer from birds to humans (that is a good thing).

Additionally, H591 and H7N9 are BOTH not well transmitted person-to-person and have a low infection rate;  most of those infected are within clusters (often family members) and those exposed to infected poultry in Asian countries.   There are NO ACTIVE RECOMMENDATIONS for any persons at this time as infection rates remain low and rare.   Common sense measures are always appropriate such as avoiding touching wild birds and animals, washing hands frequently and avoiding areas known to be infected with either virus (again, mostly in Asian countries).


Centers for Disease Control & Prevention

World Health Organization
World Organization for Animal Health (OIE)
Food and Agriculture Organization of the United Nations (FAO)