What is bird flu? why it has come? why is it danger? what's the vaccines for bird flu?is research going on?

viral disease,

As their lungs filled … the patients became short of breath and increasingly cyanotic. After gasping for several hours they became delirious and incontinent, and many died struggling to clear their airways of a blood-tinged froth that sometimes gushed from their nose and mouth. It was a dreadful business.

–Isaac Starr, 3rd year medical student, University of Pennsylvania, 1918.

All the genes of all influenza viruses in the world are being maintained in aquatic birds, and periodically they transmit to other species… The 1918 viruses are still being maintained in the bird reservoir. So even though these viruses are very ancient, they still have the capacity to evolve, to acquire new genes, new hosts. The potential is still there for the catastrophe of 1918 to happen again.

–Dr. Robert Webster, Influenza Expert, Present Day.

The pair of quotes presented above were used to begin and end a short essay I wrote many years ago on The 1918 Spanish Flu Pandemic. Isaac Starr’s words offer powerful testimonial to the harsh lethality of a killer stain of influenza, and Dr. Robert Websters observation reminds us that it would be dangerous to regard the events of 1918 as an isolated slice of history that we can safely file away and forget.

In the early part of 1995, as I cast around in search of the disease that would ultimately prove to be the true villian of the science thriller I was planning to write, influenza was scarcely on the radar scope of anyone but virologists specializing in the field of emerging diseases. Because influenza exists in the human population in an ever-present but relatively benign form, changing just a little from year to year, we tend, quite mistakenly, to think we understand the nature of the threat that it presents.
Bird Flu cannot be eradicated, we must learn to live with it
Despite the apparent “novelty” of a strain of bird flu that can sweep across the globe and kill not only the domesticated foul that carries the virus causing the pandemic, but also those humans unfortunate enough to get too close to the sick birds they tend, finding influenza in domesticated birds is not the least bit uncommon.

The natural reservoir for influenza virus is in fact the intestines of water fowl. In particular, ducks habor the virus, and suffer no ill effects from doing so. Because these migratory birds are always on the move, and because they shed virus in the waterways that they inhabit, influenza virus travels widely and is easily transmitted from bird to bird. Because of this, domesticated birds, like the turkey and the chicken, which cross paths with the virus, become infected and habor the potential to transmit the virus to humans (for example, virus secreted onto the surface of eggs could end up infecting egg handlers– for this reason, if bird handlers notice any of the following symptons in their birds they should immediately notify Federal or State animal health officials: sudden death; lack of energy and appetite; decreased egg production; soft-shelled or misshapen eggs; swelling; purple discoloration; nasal discharge; coughing, sneezing; lack of coordination and diarrhea).

Often an intermediate host, the pig, is involved in the cross-species transmission of influenza. When this happens, the result is referred to as Swine Flu. Even so, the source of the virus is generally aquatic birds.

Most strains of bird flu do not cross species and end up infecting humans. However the H5N1 strain that has in the last decade been known to infect humans, and kill them in 5 out of every 10 cases, clearly has surmounted the first of two barriers that must be cleared before a bird flu pandemic can take hold in the human population. The second barrier will be surmounted when this strain acquires the ability to jump from one human to another. This may never happen, and hopefully will not. But based on the history of pandemic flu, it seems more likely that this is just a matter of time. Whether this takes one year or twenty is just impossible to say.

The World Health Organization has estimated that a human-to-human strain of bird flu could result in an influenza pandemic with the potential to cause between 2 and 7 million fatalities worldwide. Considering the underwhelming state of health services offered by the majority of countries in the world today, these numbers do not appear to be overhyped estimates of the potential lethality of a bird flu pandemic. Should a bird flu pandemic break out with a lethality approaching that of the 1918 Spanish Flu pandemic, it is probably fair to state that the WHO prediction is likely to fall far short of the actual death toll.
Pandemic Flu vs Ordinary Flu
So what are the distinguishing features of pandemic flu as opposed to ordinarly flu? These are probably most easy compared in tabular form:

Ordinary Flu Pandemic Flu
Frequency Occurs annually, peaking during late winter Occurs only a few times per century, last seen in 1918, 1957 and 1968.
Range Affects up to 10 percent of population Higher than 10 percent, due to lack of acquired immunity. Possibly 20 to 40 percent.
Lethality Generally kills only the very young, the old, and immunologically compromised. High Morbidity. Kills also healthy adults.
Vaccine Based on similiarity to previous strains, vaccines can be prepared. Current vaccines are much less effective as pandemic strains differ substantially from ordinary flu, but this could change by perhaps 2007-2008.
Antivirals Developed for ordinary flu, and administered as needed. Not known to be effective against novel flu strains, and likely to be in short supply during a pandemic.

Emergence of a Bird Flu Pandemic?
The current candidate for the cause of a bird flu pandemic that crosses into the human population is the H5N1 strain. As discussed in my essay on The 1918 Spanish Flu Pandemic, and the Emerging Bird Flu Pandemic, this strain was first detected in Hong Kong in 1997, and in the time since then has spread halfway across the globe despite strenuous efforts to eradicate it in poultry stocks that have become infected. This movement of the virus, which requires transmission from one (bird) host to another via shared waterways, is slow in comparison to the movement of an airborne strain which can be transmitted from one human host to another in the particulate matter exchanged during coughing and sneezing events. The pandemic of 1918 spread across the globe in about six months, despite the dependence of that time on ship borne travel. In an age of international travel, this encircling time could be reduced to a matter of days. Once it begins, the likelihood that it can be stopped in its tracks is small.
Life during a Bird Flu Pandemic
One can never predict with any accuracy the way a natural catastrophe will unfold. But some speculation on life during the time of a bird flu pandemic seems worthwhile. Things we can say for certain are the following:
No country will be fully prepared for the event. This stems from the fact that no government is ever prepared for any natural catastrophe, as such preparations are prohibitively expensive. This means the bulk of the population will not have access to medical treatment when they need it. Families will be required to look after themselves. Only the patients identified in the very first stages of a bird flu pandemic are likely to receive treatment.

Medical supplies for combating a bird flu pandemic in the human population will be quickly exhausted. Even now, access to such antivirals as Tamiflu is poor in most parts of the world. (In late 2005 the makers of Tamiflu stepped up production to 10 times the normal level in response to worldwide demand for the drug in anticipation of an impending pandemic). Likewise, flu vaccines, which require a long lead time for preparation (six months or more) and can easily be “spoiled” due to inadequate preparation, will not be available in anything like a sufficient supply in the foreseeable future.

Social disruption will be significant. When workers are faced with the decision of weighing the safety of family members against the worth of their job, you can bet the absentee rate will skyrocket during a pandemic. When the loss of workers begins to affect the delivery of food supplies, power, and water, we are suddenly looking at a different kind of emergency scenario–one reminiscent of the scenes that played out in New Orleans after Hurricane Katrina struck in 2005. When the services we take for granted every day suddenly disappear, people become desparate and things go to hell rather quickly. The break down of social order may be the most frightening prospect that an emerging bird flu pandemic could bring about. The government itself warns about this possibility on its own websites, so do take this possibility seriously.

Preparing for a Bird Flu Pandemic
It is tempting for all of us, the author included, to stick our heads in the sand and hope that the news stories about the possibly of an impending bird flu pandemic are mostly hype. But this is about as wise as living in Florida and hoping you have seen the last hurricane, or living in Los Angeles and assuming that you’ll not be hit by another earthquake. Really it is just a matter of time, though no one knows how much.

There are some not-so-difficult things you can do to prepare, things that will also help prepare you for other emergency events. These seems practical to me:
Stock up on water. You can never have too much of this in storage, and it is cheap. Have at least a 3 month supply in stock at any time (6 months if practical), and rotate your supply so that you use up the oldest bottles at the rate you replace them with new ones. This way you will never have to worry about filtering existing water supplies if it comes to water shortages in your area.

Stock up on food supplies. This one is a little more difficult, but if you are lucky enough to have one of those huge freezers in your home, fill it up. Rotate your food, so that it is never more than 3 (or 6) months old. Be sure to buy only the foods you normally buy, as you’ll be eating them regardless of whether or not any disaster strikes. Dry foods can be stored separately, but people tend too forget about them and only check their supplies in the advent of an emergency. So be prepared to toss these after a year when they are no longer edible…

Purchase some quantity of air filtration masks which, in the event of a true bird flu pandemic will be regarded as indispensible when you need to leave the house and mix with the general populace. As regards what type of mask you should obtain if you are inclined to purchase a box or two (not a bad idea as you won’t be able to do it if the time comes that you need to wear them) the Centers for Disease Control and Prevention advise health workers to use a “fit-tested respirator, at least as protective as a National Institute of Occupational Safety and Health (NIOSH)-approved N-95 filtering facepiece (i.e., disposable) respirator” as one of the possible precautions against airborne infection when working with patients with known or suspected SARS or Bird Flu. 3M manufactures such masks, and the latest variety with the “Cool Flow” exhalation valve for increased comfort during extended wearing periods seems to be the mask of choice.
For other possible preparedness items you might check out a Distributor of Flu Preparedness Items (naturally enough!).

If it comes down to it, and an infectious form of bird flu arrives in your country, one of the most important things you can do to avoid infection is practice safe hygiene. This means that you go into obsessive compulsive mode and assume that everything you touch has the potential to be carrying virus. It’s somewhat pointless to assume this of the contents of your own home (unless you have a stricken person on site) but once you leave the house, it is a good operating assumption. This means under no circumstances do you touch your hands to your face while in public. Children, and adults, who have the habit of putting their fingers in their eyes and noses are extremely susceptible to infection in such an environment. When you return to your home, clothing goes into the laundry immediately and you wash your hands thoroughly with soap to rinse away any virus you might have come in contact with. You always use a face mask in public if you have access to one. Otherwise you make one. Common sense suggests that anything that inhibits the likelihood of inhaled aerosolized influenza is better than nothing. But a proper face mask is designed to be efficient at this task. These are designed to be used once only and discarded.

If you are a vendor, think about how you might change the operational nature of your business to stay afloat during a time of crisis. What can you do to reduce the likelihood that your employees will desert you? For instance, if you sell clothing you are very unlikely to receive my business if I must enter an enclosed space (a building) in order to purchase something. At such a time I do not want to breathe the air of a confined space. But if your stock was accessible in an open-air market I would probably be much more inclined. Employees will feel the same way, particularly if the goods in question are not critical to day to day survival.

Finally, do some more reading on the subject of bird flu pandemic. The information about bird flu found on this page is by no means exhaustive. Reading resources are listed below in the Related Links section.

Could a Bird Flu Pandemic resemble the Spanish Flu Pandemic of 1918?
A lot has happened in the last decade as regards our scientific understanding of the genetic mechanisms responsible for the virulence of some strains of influenza. Much of this new understanding has been a direct result of the work of Dr. Jeffery Taubenberger and his team at the Armed Forces Institute of Pathology. Back in 1998 I interviewed Dr. Taubenberger about his effort to reconstruct the genes of the 1918 Spanish Flu virus. At the time I had forseen the day when it would be possible to reconstruct the entire virus. In October of 2005, after 10 years of work by Taubenberger’s team, it was finally reported that the virus had been re-engineered. You can read about the announcement in the PBS article entitled 1918 Spanish Flu Offers Clues About Pandemic Viruses. Of particular interest is the observation that Taubenberger’s work “published in the journal Nature in October 2005, offered some parallels between the Spanish flu virus and the H5N1 strain of the bird flu slowly spreading through Asia and recently turning up in other parts of the world.” The implication here is clear. If the currently circulating H5N1 bird flu virus does acquire human-to-human transmission, the estimated mortality rates offered by the World Health Organization for a bird flu pandemic could prove to be wildy optimistic.