Why Does Bird Flu Not Cause a Major Outbreak in Humans?

Have you ever wondered why bird flu, although really bad for birds, is not as much an issue in humans?  Recent research provides us evidence of what is going on.  We'll attempt to summarize.

First, flu viruses are designated by two surface proteins H and N.
H - hemagglutinin, which enables the virus to infect human and animal cells where it can multiply,
N - neuraminidase, which helps the virus’s offspring to extract themselves from the infected cell.

So the virus enters the host cell, has the host replicate virus RNA which is used to make new viruses, and the high number of newly minted viruses explode out of the cell.  A person becomes sick as they fight off the viruses.  Worst case is when a person encounters new variants of  virus, that have different proteins including H and N, as would be the case with people getting a bird flu variant.  In this case, it takes the body longer to react to novel proteins of the variant, and the body has less defense system in place to fight the new virus.  The body reacts violently to counter the new virus, and it is this, the body's own defense system, that can be damaging (high fever, excessive phlegm, etc).

What this study found was that although the bird flu virus can infect a person, it does not replicate (make new virs) easily and thus does not spread easily.  The reason - the bird virus when in the human, does not produce a sufficient quantity of a protein, designated M1, responsible for getting the RNA out of the nucleus to begin making the new viruses in the cytoplasm of the host cell.   In humans, the bird viral RNA is spliced differently, making a protein called M2.

“Alternative splicing regulates which proteins are ultimately made from a single gene, because many genes code for more than one protein. When human cells are attacked by bird flu, this element ensures that more M2 rather than M1 protein is produced.”

May there be other factros? Sure.

 “How pathogenic an avian flu virus is and whether or not it has pandemic potential depends, of course, on many factors,” says Selbach. “A study on cell cultures cannot cover all these factors. Nevertheless, it might be useful in future to include an analysis of this RNA segment in the risk assessment of avian influenza viruses.”

https://www.mdc-berlin.de/news/press/what-blocks-bird-flu-human-cells
What blocks bird flu in human cells? 

Bird Flu Found on Tennessee Farm

Avian influenza, or bird flu, struck a Tennessee chicken farm resulting in the operation having to cull 73,500 birds.  This is the first incident of avian influenza in the US this year.  To control the issue, all bird flocks in a six mile radius will be quarantined.

While this is not a human health issue, avian influenza can impact the poultry supply if not controlled.  The 2014/2015 outbreak resulted in 48 million chickens and turkeys.

NY Times
https://www.nytimes.com/2017/03/06/dining/bird-flu-avian-influenza-chickens-tyson-foods.html?_r=0
Bird Flu Outbreak Found at a Tennessee Farm
By STEPHANIE STROMMARCH 6, 2017

Food Safety Update for July 10, 2015

Avian Influenza Outbreak in birds has come to a halt with no new cases reported since June 17th.  It has been one of the most devastating outbreaks of bird flue with approximately 48 million birds affected.  According to reports, there is a lot of room for improvement in responding to such a serious outbreak.

In Texas, there are an increased number of illnesses due to the parasite Cyclospspora.  There have been 151 cases reported.  (Story/link below).

 

In North Carolina, one restaurant has been linked to 267 cases of salmonellosis.  Bad BBQ.  (Story/Link below)

 

In a recent study, it was found that farmers should wait for 24 hours after a rainfall or irrigating before harvesting.  The research was based upon the presence of Listeria.

   

Egg Shortage - US Opens Door To Imported Eggs

The bird flu outbreak has caused an egg shortage in the US.  According to reports, some 47 million birds, 35 million hens have been affected.   To keep egg prices down and eggs available for commercial use, the US has permitted the Netherlands, Germany, Portugal, Spain and France (in Europe), and Chile and Argentina (in Latin America) to ship egg products to the US.


 Wall Street OTC
http://www.wallstreetotc.com/u-s-food-producers-trying-to-defuse-egg-crisis-with-dutch-imports/219030/
US Food Producers Trying to Defuse Egg Crisis with Dutch Imports

Jun 12, 2015 By David Warren

The U.S. Department of Agriculture had given the approval to five egg producers from the Netherlands to sell egg products to the U.S. amid efforts to alleviate egg shortage caused by the recent bird flu outbreak.

It is the first time in nearly two decades the U.S. decides to imports egg products from Netherlands. The only non-domestic egg supplier for food processors and bakeries considered safe by the USDA was Canada. Yet, egg shortage resulted in a jump in prices, so the federal government is looking for alternate solutions.

Imported egg products would be used in processed foods and bakeries, and states hope that imports would prevent prices from further rising. In Texas, a supermarket even put a limit to shell egg purchases.