The virus is carried mostly by wild waterfowl such as ducks, geese and swans, and can be transmitted by saliva, nasal secretions and feces. Though wild birds can often survive infection, for domestic poultry it is deadly within 48 hours more than 90 percent of the time. At least for now, though, H5N1 does not spread easily between people. Since 2003, only 208 people have contracted the disease and nearly all of them handled infected poultry. (A handful became sick while caring for an ill relative.) Where, then, is the danger? Because this strain of flu is new, humans have little or no resistance to it. It is also a particularly dangerous form of flu, said Dr. Richard Webby of St. Jude Children’s Research Hospital in Memphis. Unlike most viruses, which can only infect the respiratory tract, H5N1 has an extra chain of molecules that allows it to infect many other parts of the body. “My personal feeling is that if it did go into humans it would be very dangerous – a very, very nasty virus,” Webby said. Of the 208 people who got this strain of bird flu, more than half of them died. And, although a pandemic would require the virus to be spread between people more easily than it is now, viruses can change. The genetic code of viruses naturally gets altered over time, and could stumble upon an even more dangerous form. H5N1 also could acquire genetic material from another virus that moves easily between people, gaining that trait for itself. With any change that makes H5N1 easier to transmit, the situation would suddenly become more dangerous. “We’re constantly taking samples of the virus and studying it to see if it is changing,” said Centers for Disease Control and Prevention spokesman Tom Skinner. “Since this \ was first recognized back in 1997, there have been a few changes in the genetic makeup, but they do not seem to be the kind of changes that would make it easily transmittable from person to person,” he said. Whether it will, though, or how long it would take, is anybody’s guess. Virus on the move One thing health officials are sure of is that the virus is on the move. H5N1 has since spread to Europe and Africa. It has also been found in mammals as well as birds, including pigs in China and the weasel-like stone marten in Germany. To keep it out of the United States, import regulations now ban the transport of birds or bird products from any H5N1-infected countries. It probably won’t be enough, though. “I think that most experts agree that it’s likely that H5N1 will eventually arrive in North America,” Skinner said. The flu could enter either by the illegal import of bird products, or perhaps by migrating wild birds. News on that front is positive, though. Many researchers expected a swath of new countries to become infected when birds traveled from Europe to Africa and back during their winter migration. But this spring no such spread of the virus was detected. There is also no strong evidence, Webby said, that birds on the Eurasian and American flyways, which both summer in Alaska, transmit viruses between them. “Even though the birds may mix,” the viruses don’t necessarily spread, he said. “I’m not convinced it’s going to get here any time soon.” If the bird flu does arrive, the U.S. Department of Agriculture and the CDC have elaborate detection systems, Skinner said. About 200 laboratories around the country can test for the virus, and an alert system is in place to spread announcements that would hopefully keep it contained. Pandemic preparedness For now there is no danger for Americans. Even eating chicken is not a concern – well-cooked meat will not carry the disease. If H5N1 did mutate into an easily transmittable form of the disease, though, would people be able to protect themselves? Two currently available drugs, oseltamivir and zanamivir (sold as Tamiflu and Relenza) seem to have some effect on the virus. However, they usually need to be taken within two days of infection to be effective. Perhaps even more useful, therefore, would be to develop an H5N1 vaccine. (The flu vaccine available annually is not effective because it counteracts a very different strain of the disease.) But to make a completely effective vaccine, researchers have to know the exact form of the human-transmissible version of H5N1 – something they cannot predict. There is no time to waste in waiting for that form of H5N1 to appear. Because it takes at least four to six months to start making vaccine, the virus could kill millions by the time production started. So scientists are developing vaccines based on current forms of H5N1. The results of the first tests were mixed. In one clinical trial, only about 60 percent of people were protected, Webby said. Despite that, he said, “I’m in favor or stockpiling vaccine now – it’s a great idea. “I think when you’re talking about a pandemic vaccine, I think we’ve got to lower our expectations a little bit,” he said. Even if vaccinated, people would still become sick from H5N1, but it would probably prevent them from dying, he said. “The benefits of having a stockpiled vaccine vastly outweigh waiting for four to six months,” he said. Even better would be if the virus never spread in humans, something which is still very possible. “I think as time marches on there are more and more scientists out there that are thinking that this particular virus, H5N1, may not cause a pandemic,” Skinner said. “There is a good chance it could just peter out and fade away,” Webby said. But because H5N1 has the potential to be so devastating to the world population, he said, preparing for the worst-case scenario is critically important. [email protected] (626) 578-6300, Ext. 4451160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! AD Quality Auto 360p 720p 1080p Top articles1/5READ MOREBasketball roundup: Sierra Canyon, Birmingham set to face off in tournament quarterfinalsResearchers and health officials have kept a nervous eye on this bird flu – which goes by the name of its strain, H5N1 – since then. In the past 21/2 years, it has killed 115 people – a frightening number, but nowhere near the pandemic many had feared. Recently, there has also been some heartening news about the disease’s spread. It’s still anybody’s guess, though, when – or even whether – a bird flu pandemic will strike. `A very, very nasty virus’ H5N1 is one of many kinds of bird flus, only a few of which have spread to humans. In 1918, the Spanish flu swept the globe, infecting a fifth of the world’s population and killing more than 20 million people. In the decades since, no such immediately catastrophic virus has affected humans. But late in 2003, a fast-spreading illness in Asia set off concerns about an equally deadly epidemic. On farms in Vietnam and Korea, a deadly virus suddenly felled tens of thousands of chickens and a handful of people. In the end, more than 100 million poultry died from the disease or were slaughtered to contain it, but it still managed to spread.