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WORLD> Photo
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Is swine flu 'the big one' or a flu that fizzles?
(Agencies)
Updated: 2009-04-27 13:44 And, troublingly, more severe cases are also likely, said Dr. Richard Besser, the CDC's acting director, in a Sunday news conference. "As we continue to look for cases, we are going to see a broader spectrum of disease," he predicted. "We're going to see more severe disease in this country." Besser also repeated what health officials have said since the beginning -- they don't understand why the illnesses in Mexico have been more numerous and severe than in the United States. In fact, it's not even certain that new infections are occurring. The numbers could be rising simply because everyone's on the lookout. He also said comparison to past pandemics are difficult.
The new virus is called a swine flu, though it contains genetic segments from humans and birds viruses as well as from pigs from North America, Europe and Asia. Health officials had seen combinations of bird, pig and human virus before -- but never such an intercontinental mix, including more than one pig virus. More disturbing, this virus seems to spread among people more easily than past swine flus that have sometimes jumped from pigs to people. There's a historical cause for people to worry. Flu pandemics have been occurring with some regularity since at least the 1500s, but the frame of reference for health officials is the catastrophe of 1918-19. That one killed an estimated 20 to 50 million people worldwide. Disease testing and tracking were far less sophisticated then, but the virus appeared in humans and pigs at about the same time and it was known as both Spanish flu and swine flu. Experts since then have said the deadly germ actually originated in birds. But pigs may have made it worse. That pandemic began with a wave of mild illness that hit in the spring of 1918, followed by a far deadlier wave in the fall which was most lethal to young, healthy adults. Scientists have speculated that something happened to the virus after the first wave -- one theory held that it infected pigs or other animals and mutated there -- before revisiting humans in a deadlier form. Pigs are considered particularly susceptible to both bird and human viruses and a likely place where the kind of genetic reassortment can take place that might lead to a new form of deadly, easily spread flu, scientists believe. Such concern triggered public health alarm in 1976, when soldiers at Fort Dix, N.J., became sick with an unusual form of swine flu. Federal officials vaccinated 40 million Americans. The pandemic never materialized, but thousands who got the shots filed injury claims, saying they suffered a paralyzing condition and other side effects from the vaccinations. To this day, health officials don't know why the 1976 virus petered out. Flu shots have been offered in the United States since the 1940s, but new types of flu viruses have remained a threat. Global outbreaks occurred again in 1957 and 1968, though the main victims were the elderly and chronically ill. In the last several years, experts have been focused on a form of bird flu that was first reported in Asia. It's a highly deadly strain that has killed more than 250 people worldwide since 2003. Health officials around the world have taken steps to prepare for the possibility of that becoming a global outbreak, but to date that virus has not gained the ability to spread easily from person to person.
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