What is H1N1?

This virus is a brand new strain of influenza A H1N1. While other forms of H1N1 cause the common "seasonal" flu, this strain has never been detected before in swine or humans.

It appears to contain the DNA of: North American swine influenza; a swine influenza virus typically found in Asia and Europe; human influenza A; and a North American avian influenza.

The U.S. Centers for Disease Control's Dr. Anne Schuchat calls it "an unusually mongrelized mix of genetic sequences."

Why have we stopped calling it 'swine flu'?

The name was changed to dispel the misconception that the virus derived from pig products.

The name change came after about 15 countries, including China and Russia, slapped restrictions on imports of live pigs and pork from the United States, Canada and Mexico, and after Egypt needlessly ordered that all 250,000 pigs in the country be slaughtered.

The CDC was the first to use the term "swine flu" after initial analysis showed the virus had many of the characteristics of a swine flu.

Further tests revealed it also contained genetic material from a human flu virus and avian flu virus. After undergoing genetic changes (called "antigenic shift"), what likely started as a swine flu has now become a human swine flu.

Aren't pigs now getting this flu?

The Canadian Food Inspection Agency reports that a herd of pigs in Alberta tested positive for this H1N1 strain. The pigs were likely exposed to the virus from a hog farm worker who had recently returned from Mexico and had been exhibiting flu-like symptoms.

The pigs then developed the symptoms of flu: a sudden fever, a barking cough, sneezing and decreased appetite. All the infected pigs have recovered, as has the individual who travelled to Mexico.

How did this new strain develop?

No one yet knows.

It is likely that pigs were the "reservoir" where the virus developed, since pigs are notorious "mixing bowls" for viruses. But even though this new strain of flu contains some elements of swine influenza virus, it may not have started in pigs. It could as well have been bred in birds or even another mammal.

The investigation could take a while and it's possible the answer will never be found.

Why is a new flu strain worrisome?

If an influenza virus changes and becomes a new strain against which people have little or no immunity -- and if this new strain can easily spread from person to person and cause severe illness in a high percentage of people that it infects -- the seeds would be sown for a pandemic that could sicken and kill many people around the world.

Epidemiologists have been warning for years that it's just a matter of time before a new strain of the flu emerges that has the potential to kill millions. Flu pandemics have historically occurred about three times per century and the world hasn't seen one in more than 40 years.

What is a pandemic?

A pandemic is an epidemic of infectious disease that has spread across a large region, such as across continents or worldwide. But a pandemic can be mild or severe, depending on how many deaths the disease causes.

When most of us think of flu pandemics, we think of the 1918 Spanish Flu. But remember that the 1968 Hong Kong flu epidemic killed only about 700,000 worldwide. That's less than many yearly outbreaks of garden-variety seasonal flu.

If the current human swine flu outbreak is declared a pandemic, it is more likely to be of the 1968 variety because we have been exposed to several parts of this virus before. We also have good public health systems that are ready for a pandemic with antiviral medications and infection control measures.

As well, the number of deaths from this virus has been relatively low. Outside of Mexico, there has been only one death. In other countries, such as Canada, it's causing such mild illness that it's running its course in two to three days, in some cases without treatment.

Do we have a pandemic strain of influenza virus here?

Probably. It's clear we have a new infectious disease, one of the WHO's criteria for a pandemic. We also know it's causing human-to-human spread between people in very close contact. But we're not yet sure it it's causing "third generation infection," i.e.: the virus is passing easily from person A to person B and then to person C. If it can do that easily and in many countries around the world, that would be enough for the WHO to declare a pandemic.

How is the virus transmitted?

Human-to-human transmission of swine flu is believed to occur the same way as seasonal flu, mainly through coughing or sneezing of people infected with the influenza virus.

People also can become infected by touching something with flu viruses on it and then touching their mouth or nose.

Is there a vaccine?

There is no vaccine, as the genetic makeup of this virus is still being analyzed.

But CDC officials have prepared a "seed stock" of the virus that could be used in the manufacture of a vaccine, though it is still premature to send it to pharmaceutical companies. Preparing a new vaccine would likely take several months.

For swine influenzas that affect pigs, there is a vaccine available that can be given to pigs; there is no vaccine to protect humans from swine flu.

I got the flu shot this year. Am I protected?

Not likely. This is a virus that has never been seen before; therefore, vaccines for human flu would not provide adequate protection from the swine flu material contained in this virus. It may offer some protection though against the human flu genetic elements.

Can people catch swine flu from eating pork?

No, you cannot get swine influenza from eating pork or pork products.

What are the symptoms of swine flu in humans?

Symptoms of swine flu are similar to those of our regular flu, with sudden onset of:

• fever
• lethargy
• lack of appetite
• coughing

Some people with swine flu have also reported:

• runny nose
• sore throat
• nausea, vomiting and diarrhea.

How can I protect myself from this virus?

Since influenza spreads through spit and spray as well as contact with contaminated surfaces, the usual good personal hygiene habits are the best defence.

• Wash your hands repeatedly through the day with soap and water or with alcohol-based hand sanitizers
• Avoid touching you mouth, nose or eyes with your hands unless they've been washed
• When coughing, cough into a tissue and throw it in the garbage
• If you cough into your hand, wash your hands immediately
• Sanitize surfaces that may have come into contact with the virus
• If you become ill with flu-like symptoms, stay home

With human flu, the virus is most contagious between the second and third days after infection -- sometimes before symptoms appear -- and the virus remains contagious for about a week in adults and up to 10 days in kids.

Can we treat swine flu in humans?

Yes, for the most part. Most of the infections have been treated successfully, though there have been deaths in Mexico.

In many cases, patients with this swine flu have recovered on their own. In those who have had to be hospitalized, this virus has been treated with antiviral medications. The virus appears to be resistant to amantadine and rimantadine but has been susceptible to zanamivir and oseltamivir (Tamiflu).

Have there been swine flu outbreaks before?

Yes. Most famously, there was an outbreak in 1976 at Fort Dix, N.J., among military recruits that grabbed big headlines at the time.

Worried that they had the beginning of a pandemic on their hands, U.S. officials ordered the manufacture of swine flu vaccine and the country launched a mass immunization program that saw about 40 million people vaccinated.

But the outbreak didn't turn into a pandemic and went away as mysteriously as it appeared.