Biology 103
2005 Second Paper
On Serendip

The avian flu, while typically hosted by birds, has been infamously known to transmit to human beings, producing catastrophic results. The avian flu is currently a serious issue of concern, as its effects are being felt worldwide. It was first identified in the early 1900's in Italy and has remained a potent threat, as the death toll from this virus continues to rise. Historically, the most destructive avian flu was the 1918 "Spanish flu", which is thought to have killed 50 million people. Currently, the H5N1 strain of the avian flu, a highly pathogenic form of the virus, has spread throughout many parts of Asia and into Europe, killing many people and birds. Fear of another avian flu pandemic is mounting, as scientists work diligently to develop innovative treatments and governments try to sequester the fears of civilians. Due to the attention that this disease has been receiving as well as the emphasis that has been placed on the need to self-protect, both the nature of the disease as well as available treatments are worthy of further exploration. (1)

The avian flu virus is composed of the Influenzavirus A genus of the Orthomyxoviridae family and is a single-stranded, segmented RNA virus. Flu viruses are subdivided into subtypes according to antigens in the haemagglutinin (H) and neuraminidase (N) protein projections on their surfaces. The avian flu has representatives in all of these subtypes, but the most common avian viruses belong to either H5 or H7 subtypes. Furthermore, the avian flu virus can be subdivided into either high or low pathotypes depending on its virulence. (2)

At this point one might be asking the fairly obvious question: if this is a bird flu, how can people contract the virus? It is indeed true that the avian flu originates in waterfowl, birds, and domestic poultry, but the flu can be easily transmitted through their saliva, feces and nasal secretions to humans. While a weaker strain of the virus infects the respiratory and gastrointestinal tracts of birds, a highly pathogenic strain such as the H5N1 strain that is currently plaguing Asia and Europe, can spread to virtually all parts of an infected bird or mammal, including the meat. Therefore, H5N1 can be spread through the distribution of contaminated food products. This strain of the virus is also able to survive in low temperatures and therefore can be found in frozen meat. H5N1 can also last for up to 35 days at low temperatures in the feces of these infected animals and can survive on surfaces, such as those within the poultry house environment, for several weeks. (3)

Human outbreaks of strands of the avian flu have originated in crowded conditions where poultry and humans live in close quarters, as demonstrated with the current outbreak of H5N1 in eastern Asia. Another point to note is that many birds are migratory, and are therefore able to spread the virus to all parts of the world. Viruses also replicate and mutate at such a high rate that they are able to evolve into a form that more easily infects humans. Furthermore, the virus could mutate to the point that it can be easily spread during human-to-human contact, which was the case in the 1918 avian flu pandemic. Coughing, shaking hands, and traveling in airplanes could potentially provide the optimum environment for procreation of this virus. Therefore, due to the ability of the virus to rapidly mutate, spread, and kill, it is clear why this issue is receiving so much global attention. (2)

The H5N1 strain of the avian flu has been circulating in Asia since 1997. In 2004 and 2005, 118 people were infected with the H5N1 virus and 61 of them died. More than 120 million birds have died as a result of this strain of the avian flu, or have been killed to prevent further infection. This particular strain (H5N1) goes directly deep into the lungs, causing severe pneumonia, and in many cases, death. This is unlike the normal human flu, which predominantly affects the upper respiratory tract causing congestion, runny nose, and sore throat. (2)

Although H5N1 does raise serious health concerns, there are defenses available to combat this virus. First and foremost, prevention tactics adopted by many governments focus on killing infected animals as well as those suspected of being infected. While killing infected animals will certainly limit the spread of disease, it seems virtually impossible to effectively stop it using this method. It is unlikely that all of the infected animals will be killed, particularly if the animal does not initially display signs of the disease when examined. Especially because many birds are migratory in nature, it would also be difficult to successfully quarantine the disease.

Another means of protection against the virus relies on medical resources. Although there is no vaccine currently on the market for the H5N1 virus, scientists are in the process of manufacturing one. Richard Webby of St. Jude Children's Research Hospital has "reverse engineered" a version of the H5N1 virus that could be the basis for a vaccine by keeping the parts of the virus that are recognized by the human immune system while immobilizing the critical disease-causing function. The resulting vaccine has been tested on 450 volunteers and produced successful preliminary results. Like most vaccines, to ensure the success of the inoculation, two shots will be needed, each administered about a month apart. The government has awarded a $100 million contract to Sanofi Pasteur of France, to manufacture 20 million doses of this vaccine. However, it is difficult to manufacture because it requires injecting the virus into live chicken eggs. (4)

Antiviral drugs are also being developed as another mode of defense against the avian flu. Tamiflu was developed by Swiss drugmaker Roche and has been touted as the drug that could possibly save the lives of millions should the flu develop into a pandemic. Tamiflu is a neuraminidase inhibitor, allowing it to treat the cause of the flu infection by inhibiting the critical neuraminidase protein on the surface of the virus. Viruses replicate by seizing a cell's genetic machinery to copy themselves and Tamiflu prevents these copies from escaping to infect new cells. It has only been tested against H5N1 in cell cultures and mice but produced successful results in both cases. It has also been proven to work against milder forms of the flu in humans, shortening duration and intensity of a weak strain of the flu virus if administered in the first 48 hours after symptoms occur (5)

However, Michael Osterhold of the University of Minnesota asserts that he is not certain if Tamiflu will work against H5N1 because "the disease goes so quickly to high levels of infection, you might need to take it before you get exposed" (5). Furthermore, the United States only has enough Tamiflu to treat 2.3 million cases, with about 10 million on order. The United States government is trying to stockpile enough medication to treat 20 million people with the drug, but a lot of Roche's production is now committed to other countries that had placed orders earlier. President Bush has responded to this lack of supply by holding a meeting with drug-company executives urging them to speed up their work on vaccines and antiviral drugs. (5)

Another line of drugs, which includes amantadine, targets the M2 protein, "a proton channel found in the viral membrane" (6). Unlike Tamiflu, these drugs are relatively inexpensive and are widely available. However, the potential of these drugs seems to be stunted because it was discovered that China had been giving amantadine to poultry since the early 1900s, creating a strain of the virus that is now circulating in South East Asia that is resistant to the medication and now even more dangerous to humans. However, the strain of H5N1 that is circulating throughout Northern China, Mongolia, Kazakhstan, Russia and Europe is not amantadine resistant. (6)

I think that the frenzy over the avian flu is certainly warranted, especially given the historical context of the 1918 avian flu pandemic in which tens of millions of lives were lost. I also think that it is interesting that a country as powerful as the United States, which seems to be unbounded by its resources, finds its toughest competition in a microorganism that cannot even been seen with the human eye. The United States, and the world in general for that matter, seems to be helpless in the face of this virus. Even though vaccines and antiviral drugs are being developed, there seems to be a lack of preparation and knowledge surrounding this virus. The vaccines are just being developed and the antiviral drugs have only been tested to work only in a Petri dish, mice and on mild strains of the flu. While I realize that we are now taking aggressive measures to speed up the manufacturing of medicines, I hope that it will not be too little too late. A worldwide flu pandemic, such as the one that took place in 1918, would be devastating and its effects would be catastrophic. While it is certainly ironic that an organism that could only be viewed underneath a microscope could potentially rid the world of the human race, it is a serious and unsettling circumstance that hopefully we will not have to grapple with.

Sources

1)1918 Flu, Information about the 1918 "Spanish flu"

2)Avian Flu, Information about the avian flu

3) Avian Flu, More Information about the avian flu

Newsweek: October 17, 2005. Volume CXLVI, No. 16. "The Race Against Avian Flu." Jerry Adler and Anne Underwood.

5)Tamiflu, Information about antiviral drugs

6)Avian Flu, Background Information on the avian flu


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