Swine flu has been grabbing news headlines since the first major outbreaks were reported in Mexico and the United States. It's now spread to Europe and Asia, and the first death outside Mexico has been confirmed in the United States.
But what is swine flu; how do people get infected, and how can they protect themselves against infection? For answers RFE/RL turned to microbiologist Hugh Pennington, emeritus professor at Aberdeen University in the United Kingdom.
RFE/RL: Could you set us straight on what swine flu is -- it's a new form of the type of flu virus that normally infects pigs but not humans, is that right?
Hugh Pennington: This new virus is called swine virus because it's got components from pig-flu viruses in it. One of the components comes from American swine-flu virus, one comes from European and Asian swine-flu virus but it also has human- and bird-flu components as well.
So it's a sort of mixture of [different] viruses, one from pigs, one from birds, and one from humans. It's a brand new virus, it's a mixture of viruses that have been circulating in the world for some while.
RFE/RL: How did it arise? What do we know about that so far?
Pennington: We really don't know where it came from, how it arose. The guess is, and it's probably quite a reasonable one, is that a pig got infected with a human virus and a bird virus while it was already infected with one of its own viruses.
And we know that pigs can be a kind of melting pot for this kind of mixture of viruses to take place and new viruses to appear, because we've seen this happen in the past, not so much with pigs but with birds and humans as well, that viruses from different species can -- when they infect one animal or one human -- can recombine and make a kind of new virus by resorting themselves.
RFE/RL: So the first case in humans might have come from contact with infected pigs?
Pennington: That's right, and we'll probably never know because very often when we try and track these things back the trail goes cold, that things have moved on. People will try to find out if this virus is occurring in pigs or not but I wouldn't be too optimistic about that. That's probably what happened but when it happened one can't say, unfortunately.
No Risk From Pigs, Pork
RFE/RL: But now it's being transmitted from human to human?
Pennington: Yes, this is what's new about this kind of virus. We've known about pigs getting influenza for a long time, the first description of this happening was in the 1930s.
Very occasionally people who look after pigs have caught flu form the pigs, but usually what's happened, nearly always what's happened is that in a sense it's been a dead end for the virus, the virus infects the pig handler and they get the flu but they don't' pass it on to other people. But what's happening this time is that clearly this virus is well adapted to humans so it's spreading from person to person.
RFE/RL: Is there any risk from eating pork?
Pennington: No there's absolutely no risk from pork. It's a bit unfortunate this virus has got this name, which gives this kind of idea that maybe it's something to do with pork and pig products. Absolutely no risk at all, absolutely no risk.
RFE/RL Is it a misnomer to call it swine flu then? Are people focusing on the wrong thing when they worry about pigs, pig farms, pork, when actually it's other people that pass the infection on?
Pennington: That's right. It's moved on from being a pig virus. It's pig virus ancestry in it, but just like most of the flu viruses that infect people , they all have a bird ancestry in them way in the distant past, but we don't call them bird flu, we just call them flu. This is just an ordinary flu virus now and how dangerous it is of course only time will tell unfortunately.
RFE/RL What are the symptoms in humans?
Pennington: So far the ones that have been studied best are the ones that have occurred outside Mexico, people who have traveled to Mexico, picked the virus up and fallen ill outside, in the United States or in Scotland or in Spain or other countries. So far all of [those] cases have been pretty mild, only one or two people have been admitted to hospital.
Most of the people have just had, they've felt a bit ill, they've perhaps had a bit of a temperature, a cough, a runny nose, perhaps feeling a bit of aching in the limbs. One or two of them had food-poisoning symptoms like diarrhea and vomiting, which is what we'd expect to see in flu. This is the normal pattern in normal kind of flu infections.
So there's no way we can tell by asking somebody what their symptoms are whether they've had this virus or another flu virus and there are other viruses, not flu viruses, that cause these kind of symptoms.
RFE/RL Since the symptoms are so like those of ordinary flu when should someone suspect they have been sickened by this new virus?
Pennington: It's Mexico where the virus is circulating on a large scale, so the only people at the moment who even need to think about the possibility of them having swine flu are the people who've been to Mexico recently or have had very close contact with people who've just got back from holiday there.
Treatment, Not Vaccines
RFE/RL Can it be treated by antiflu drugs like Tamiflu?
Pennington: Yes we know this virus is sensitive to Tamiflu and the other antiviral drug that you take by puffing on an inhaler. This stops the virus growing, basically.
It's early days to say exactly what happens in patients. Some people have been treated with it so far but they had a mild infection and so it's hard to know whether the Tamiflu had much effect.
What happens with Tamiflu is that if you get the symptoms and get treatment, it doesn't stop the symptoms at once, the symptoms get milder and the illness lasts a bit of a shorter time than It would otherwise. But most people get better anyway without any treatment.
RFE/RL What if I've had a flu vaccine this year, will that protect me?
Pennington: No. The flu vaccine used currently doesn't protect people against this new virus. There's a fair amount of discussion now about whether a new vaccine should be prepared that has the swine-flu virus in it either as a single vaccine or to put it in next year's vaccine. The vaccine for the coming year -- the flu season in Europe is in the winter -- they're busy making the vaccine for the coming season and the question being looked at is whether they should stick that new virus into that or not.
RFE/RL How soon could a new vaccine be developed?
Pennington: Preliminary work is under way, that is, getting virus and making it into a vaccine virus, which is technically a fairly straightforward exercise to do.
The big question is do we move into vaccine production, which is a more expensive job and involves the companies that make the vaccine having to turn over to production of it. And of course the vaccine itself has to be tested to see if it works and is safe and that takes time.
So I don't think there would be any vaccine available for probably four-six months to start vaccinating reasonable numbers of people.
RFE/RL: So the seasonal flu vaccine is no protection. How can people avoid being infected?
Pennington: At the moment it's down to good common sense, like washing your hands after you've sneezed, don't sneeze into your hands if you can avoid it, use disposable paper tissues to sneeze into rather than the traditional handkerchief. Those sort of good personal hygiene practice, washing your hands is emphasized a lot. It won't prevent you getting the flu but it will reduce the risk if you got it of spreading it to someone else. Apart from that there's not much one can do except for watch for the advice coming out from public health officials.