Pentakarn

- Influenza is thought to spread mainly person-to-person through coughing or sneezing of infected people.

- If you get sick, CDC recommends that you stay home from work or school and limit contact with others to keep from infecting them.

How Long Until Symptoms Appear After Being Infected?

Experts agree that the incubation period of this virus in probably no more than a week. Infectious symptoms would probably appear within 7 days after exposure.

The World Health Organization is considering raising the pandemic alert to Phase IV, which means increased evidence of Human transmission. Prior to Monday, April 27, 2009, the level has been at Phase III, which means limited transmission.

Can masks help stop flu spread?

By Nick Triggle

Health reporter, BBC News

Masks have been handed out to the public in Mexico

One of the abiding images of the swine flu outbreak is the pictures from Mexico of people wandering the streets wearing masks.

And as the disease has spread from country to country, reports have emerged of people purchasing all sorts of products on the internet.

But while the scramble is understandable, experts are sceptical about just how useful they are. Professor John Oxford, a virologist at leading London hospital, The Barts and the London, said: "Really, there is very little evidence that masks actually offer much protection against flu. I think handing them out to the public as has happened in Mexico just destroys confidence."

Health staff

It is these sorts of issues that has prompted officials from groups such as the World Health Organization and England's Health Protection Agency to steer clear of calling for them for general public use.

While Mexico has handed them out to members of the public, most other countries, including the UK, are just reserving them for health staff.

Others, such as Belgium, have bought some for flu patients, while several, including Spain, have handed them out to passengers on planes returning from affected areas.

It is believed there are enough masks for half the NHS workforce, but officials are already in discussion with suppliers about ordering another 30m to help cope if a pandemic develops. Health workers have been told to wear them, along with special gloves, if they are in contact with potential victims.

Professor Oxford believes this approach is right. "They are the people who will be most likely to be coming into contact with the virus and the ones who could be passing it on."

The Department of Health has focused on getting what are known as respirator masks. These have filters, which stop a person breathing in some particles in the air. They are much more effective than the standard surgical masks or dust masks that are sometimes used by builders.

However, none of the masks can stop 100% of the particles getting through and become less effective once they become moist. Instead, they are better at stopping the virus getting out.

Spread

Dr Ronald Cutler, deputy director of biomedical science at the University of London, said: "If you sneeze with a mask the virus will be contained so from that point of view if everyone wore them it might stop the spread.

"Or you could get the people with flu wearing them, but by the time they are diagnosed it could be too late.

"And the problem is that when someone sneezes they tend to take a mask off. I think masks give people a false sense of security.

"They are not bio-chemical suits. Masks are obviously just covering one part of the body so your hands and clothes could all have the virus on and when you take them off you will infect yourself.

"However, because people are wearing a mask they will think they are protected and may go into crowded areas.

"The best advice is to wash your hands and cover your mouth when sneezing." Gail Lusardi, an infection control specialist at Glamorgan University, agreed.

"Masks alone will not prevent spread of the influenza virus and basic hygiene measures like hand washing, safe use and disposal of tissues and cleaning of environmental surfaces are key to preventing infection transmission."

She also said it was important they were correctly fitted - some of the more expensive respirator masks are molded to fit the face unlike standard masks that can be bought on the high street.

And she added: "A mask can be worn continuously for up to eight to 10 hours, but must be replaced if it is taken off at any stage."

Don't Blame the Pigs

By Jeffrey Kluger, From Time

Wednesday Apr 29, 2009

Pity the poor pig. The otherwise estimable mammal has never had a very good representative — something about the mud, the snout, the oink. Now add the flu.

The swine flu outbreak that has sparked widespread fear — so much so that Egypt has ordered the slaughter of the country's 300,000 pigs, even though no cases have been reported there — is easy to pin on the eponymous animal from which it emerged, but the fact is, the current epidemic is little more than an accident of evolution. If pigs are to blame, so too are birds and humans.

The problem begins with the wily nature of the influenza virus itself. It may be an uncomplicated thing, made up of nothing more than 10 proteins assembled into a genome that's simple even by microbiological standards, but that bare-bones genome is unusually flexible, with snap-in, snap-out gene segments that allow easy mutation and exchange of information with other viruses. That's the reason we need a new flu vaccine every year: by the time one flu season has ended and the next one begins, the virus has changed so much, it can simply shake off last year's shot. Compare that with, say, polio; the vaccine was perfected in 1955 and hasn't had to change much since.

What keeps the flu relatively in check is that there simply aren't that many species that are susceptible to it — with humans, pigs and certain kinds of birds leading the list. "There are surface markers on the cells of some species that bind with sites on the flu virus," says Dr. Peter Daszak, an emerging-disease ecologist and president of the Wildlife Trust. "The influenza virus evolved along with pigs, and it did the same with a few other mammals and with birds."

The adaptability of the virus, however, made it a certainty that a strain that evolved in one of the susceptible species would easily make whatever changes were necessary to allow it to survive in one of the few other eligible hosts. So quickly and efficiently does the virus transform itself that it may require just a single passage through a single individual to get that shape-shifting job done.

"Different viruses from different sources enter a cell, and the virus that comes out the other end is an entirely different one," says Dr. Richard Webby, an infectious-disease specialist at St. Jude Children's Research Hospital in Memphis and the director of the hospital's World Health Organization collaborating center. "The process is called reassortment."

Birds are the natural reservoirs of the common flu strains that strike in winter — and those strains reassort themselves to hit humans particularly hard. But while humans are not susceptible to every strain of avian flu, pigs definitely are. When bird flu viruses replicate in pigs, they pick up the viral machinery that gives more selective flu strains the power to spread to other mammals, like us. That's what makes pigs such potent mixing bowls for flu. The roundabout bird-pig-human route may be less common than the straight bird-human jump, but it may be more problematic. Strains of avian flu, like the much-feared H5N1, can infect individual humans, but they can't make the person-to-person leap. Avian flu that is passed through the pig's mammalian system, however, can be passed readily among humans.

All of this made the flu virus a tenacious foe from the outset, but once humans invented farming and learned to cultivate animals, we made a bad situation much worse. All at once, chickens, ducks and pigs — which never had much to do with one another — began living cheek to jowl in high numbers and often unsanitary conditions. Farm families and people working in live markets then began mingling with the critters. That's a pathogenic speed blender, and the viruses have taken full advantage of it. "It's really an ecological issue," says Daszak.

So if we can't fairly blame the pigs (indeed, the CDC has officially stopped calling the virus "swine flu," opting instead for the more hog-friendly 2009 H1N1 flu), can we blame Mexico? That charge doesn't stick either. Decades ago, numerous countries came together to develop the Global Influenza Surveillance Network (GISN), which allows epidemiological teams to spot new flu viruses as soon as they emerge and get vaccines ready in time. But the GISN only tracks human flu, meaning animal flu can slip by undetected. What's more, pigs that carry influenza tend not to die en masse the way flocks of birds do, eliminating the immediate tip-off that a serious pathogen is at large. None of that is Mexico's fault either.

In fact, since human tourists and domesticated animals cross into Mexico all the time, there's every reason to believe that the progenitor virus behind the epidemic hitched a ride in one of them.

"I'm of the opinion that this doesn't have to be a Mexico-originated virus," says Daszak. "Somehow it got to Mexico and then mixed with humans."

If we have to pin the rap somewhere then, forget any one species or country and blame simple biology. But regardless of whence the virus came, the more salient question is, Where will it go? That's what concerns doctors as they work to stem the epidemic and make sure healthy people stay that way.

My reaction

1. Although swine flu believe to emerge from pigs, people still afraid of consuming it because they misunderstanding about swine flu's transmission which in fact, the transmission is only from human to human.

2. Vaccines are available for pigs in order to protect the dreadful disease while there is no vaccine to protect humans from swine influenza.

3. Government from every country should have stricter security at their airports as much as they can. So that there would be no more spread of the virus to others. If they found infected people on some flight, all passengers on that flight must be quarantined also diagnose them until they save.

4. Keep your body especially hands to be cleaned; washing hands routinely with soap and warm water.

5. The best way to avoid infection is to use hand-sanitizers to keep your hands clean for all times.

6. Avoid contacting with sick people as much as possible. If you are sick, stay at home.

7. If you really have to go abroad by air, preparing a facemask is a good idea in case it is needed.

8. We should often check newspaper, television, or on the internet in order to be up-to-date to the current situation of Swine flu around the world.

9. Do not panic of swine flu too much.

Conclusion