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What is the H1N1 virus, commonly known as swine flu?

H1N1 is the designation for this particular strain of flu. The combination of letters and numbers denotes the number of proteins on the virus.

The genetic components of the H1N1 virus are unique and have not been seen before by researchers.

Why is it called swine flu?

Any animal species — humans, swine, seals and birds, to name only a few — can serve as mixing vessels for flu viruses. Any animal can be affected by multiple flu viruses simultaneously, enabling the genetic materials in these various viruses to become exchanged, yielding a different virus.

In the case of the H1N1 virus, the genetic exchange apparently occurred in swine.

Where did the strain come from?

The origin of H1N1 has not yet been determined, though it is presumed to have originated in Mexico, possibly as recently as March 2009.

Does the H1N1 flu virus pose a threat to humanity?

To fully understand the current H1N1 flu virus, it must be viewed among flu viruses as a whole. Each year, seasonal flu and its complications claim between 33,000 to 35,000 lives in the United States — 300 in Alabama alone — though most people seldom panic with the arrival of flu season. Most of these victims are the very old and very young and who typically suffer from underdeveloped or weakened immune systems.

H1N1 presents a threat because it appears to be especially well-equipped to spread within small populations. However, at this writing, only one person — a 23-month-old child — has died as a result of exposure to the disease. So far, the virus is considered a moderately virulent strain and has not developed into a super strain resembling the flu strain that claimed tens of millions of lives in 1918.

Flu viruses are highly unstable. For this reason, H1N1 could become a more or less virulent strain within the next few weeks.

Some scientists speculate that the strain could prove highly transmissible though relatively moderate in its effects.

What is the difference between swine flu and the seasonal flu viruses that affect humans year after year?

Essentially nothing. In this case, the H1N1 strain happened to originate in swine — hence the term, swine flu. The next serious flu strain could originate in people, birds or some other animal.

Why does the virus seem less virulent in the United States than in Mexico, where it presumably originated?

Scientists are not sure. It could stem from differences in the quality of health care in these two countries or the rates of diagnosis. The strain could have undergone some sort of genetic recombination since its introduction into the United States.

Why does mutation seem to occur so readily in viruses?

In a manner of speaking, mutation is the nature of the beast.

Viruses are known to mutate in two ways: genetic drifting and shifting.

Viruses have a built-in genetic tendency to drift, resulting in a steady accumulation of mutations. In the course of this drifting, a virus, such as the case with H1N1, can develop into a form that could be spread from person to person.

Another method involves shifting, which occurs when two or more viruses invade the same cell and begin exchanging genes, possibly developing into a hybridized form that could threaten humans.

Scientists also believe a virus could be transformed into a deadly human strain by a simpler method --- recombination, a process that, until now, they dismissed as only a minor contribution to genetic variation.

In this case, the viruses simply recycle old mutations by exchanging pieces of genes from among their own gene segments or from the same genes of another strain or subtype infecting the same cell. This is not only a more efficient process , but one that appears to be followed by all viruses --- not only influenza but HIV, SARS and West Nile virus.

What was the 1918 flu pandemic, and why is it mentioned so often when the threat of a future pandemic is discussed?

Some health authorities believe a future pandemic outbreak could closely parallel what happened in 1918 — considered the worst flu pandemic in human history — when a form of avian flu mutated into a type that could be transmitted from human to human. It was an unusually virulent strain of avian influenza that killed between 50 million and 100 million people around the world from 1918 to 1919.

Other health authorities are more optimistic. They believe that vast improvements in health care and the widespread availability of modern drugs could mitigate some of the effects of a pandemic.

What is the U.S. government doing to protect us should such an outbreak occur?

The federal government already has gone into full emergency mode, distributing drugs and some vaccines throughout the country.

Is a vaccine against H1N1 currently available?

No. A debate is ensuing among federal health authorities over whether developing a vaccination is currently necessary.

Many medical authorities believe the virus will burn itself out in the summer before widespread vaccination is required. Vaccines also require considerable research and testing before they can be administered safely.

Based on the medical disaster associated with an outbreak of swine flu in the mid-1970s, many within the scientific community are reluctant to develop and administer a vaccine quickly without adequate research and testing. The vaccine administered to millions of people following the outbreak of a strain of swine flu in 1976, resulted in hundreds of deaths and cases of paralysis stemming from complications associated with the vaccine.

What is a pandemic?

A pandemic is an epidemic that spreads over the entire planet or, at least, an entire region.

Will a seasonal flu shot protect me against swine flu?

No. The human influenza seasonal flu vaccine is not effective against H1N1.

Even so, some experts believe that strengthening the immune system with vaccination for seasonal flu may provide an indirect safeguard against swine flu. They consider it part of an effective health maintenance program.

When will we know a pandemic is happening?

Most likely, we will know when we are alerted by one of the surveillance networks already in place at the local, state, national and international level to monitor for evidence of a pandemic outbreak.

How worried should we be that such a pandemic could occur?

The threat of the H5N1 strain developing into a form that could threaten humanity is conceivable and should not be discounted.

Even if these outbreaks eventually develop into a pandemic, it is important to bear in mind that medical science is far better equipped to deal with a pandemic than it was in 1918. Antibiotics are now widely available to treat bacterial infections that likely will accompany such a virus. Marked improvements in surveillance and sanitation have also occurred in the last century.

Why do some people seem to be more vulnerable to swine flu and other flu strains than others?

Immuno-compromised people, such as the very young, the very old and AIDS suffers, to name a few, typically are more vulnerable to the effects of influenza compared with others.

Should I avoid eating pork products?

According to the U.S. Centers for Disease Control and Prevention, swine influenza viruses are not transmitted by food. Swine flu cannot be acquired from eating pork or pork products. Eating properly handled and cooked pork products is safe.

Moreover, even as the veterinary community is closely monitoring the swine population in the United States and throughout the world, there has been no detection of the virus in any single animal.

What are drug manufacturers doing to help prevent a pandemic?

Drug manufacturers are ramping up production of Tamiflu, which has been shown to be effective in treating H1N1. The U.S. government already has amassed a large reserve of Tamiflu, some of which already has been dispersed throughout the country, to ensure it will be readily available in the event of an outbreak.

A system is already in place to ensure that even larger supplies of Tamiflu are produced in the event of an especially serious pandemic.

Written and compiled by Jim Langcuster, Alabama Cooperative Extension System news and public affairs specialist, Alabama Cooperative Extension System, in conjunction with Dr. Robert A. Norton, veterinary bacteriologist and Auburn University professor of poultry science.

 

 


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