* CDC website traffic up sharply this week
* Random Google search of "swine flu" yields 5.4 mln hits
LOS ANGELES, April 28 (Reuters) - Swine flu chatter spread swiftly through blogs and social network sites like Twitter and Facebook on Tuesday while U.S. cable news networks' saturation coverage of the outbreak gave way to a major political story.
"As the number of swine flu cases continues to climb, so does public interest in the (flu) outbreak. Americans are looking for more information on the outbreak and specifically for symptoms to look out for," said Heather Hopkins, analyst for Hitwise, which tracks Internet usage.
Online searches for the phrase "swine flu" during the past week have sent millions of Internet users to Wikipedia, Google and websites of the U.S. Centers for Disease Control and Prevention in Atlanta, according to online tracking experts.
For example, a random Google search on the words "swine flu" late on Tuesday yielded about 5.4 million hits.
Online traffic to www.cdc.gov jumped 442 percent in the week ending April 26, and "we are likely to continue to see an increase in Internet visits to the CDC site over the coming days," Hopkins said.
Much of the online buzz was propelled by social networking sites, said Susannah Fox, associate director at the Pew Research Center's Internet & American Life Project.
"Social media create a hive of information, and we are the bees who are dipping into the hives and then going back into the real world with the information that we find," she said. "Some people are really into the hive ... spending a lot of time on Twitter, Facebook and using these social media."
The new strain of flu has been blamed for as many as 149 deaths in Mexico, while the cases documented in the United States and other countries have been mild by comparison.
Still, some experts believe the intensity of media coverage has raised the public's anxiety level.
"There's a distinction between obviously keeping our readers and viewers up to date and sensationalizing the story. The media tends to love doomsday scenarios like bird flu, Y2K (year-2000 computer scare) and the guy flying around with TB (tuberculosis)," said blog publisher Arianna Huffington.
"It's easy for the media to get into panic mode coverage, but very often these things don't pan out, and the problem is that we're becoming like the boy who cried wolf," she said.
Robert Thompson, professor of media and popular culture at Syracuse University in New York, agreed that the media has to balance restraint with the imperative of covering an important story.
"If as many people had swine flu as those that are covering swine flu then it would be a pandemic to reckon with," he said.
After wall-to-wall flu coverage on Monday, the major U.S. cable networks -- CNN, Fox News Channel and MSNBC -- turned much of their attention on Tuesday to U.S. Senator Arlen Specter's switch from the Republican to the Democratic Party.
"Cable news channels have a very hard time covering two different stories simultaneously," independent media analyst Andrew Tyndall said.
MSNBC President Phil Griffin said Monday's flu coverage was "event-driven" by briefings from high-ranking officials, including President Barack Obama, Homeland Security Secretary Janet Napolitano and New York Mayor Michael Bloomberg.
But the networks filled time between news conferences with interviews of public health officials urging people to wash their hands and cover their faces when they sneeze or cough.
"The public health authorities know they have these channels available for getting their message out," Tyndall said. "There's not much journalism going on. They're offering carriage to a message that they're not controlling very much."
Griffin said news executives are always mindful of the potential for stoking unwarranted public anxiety.
Pew Research's Fox said those following the story are increasingly turning to the Web and seem headed toward informative rather than sensational sites.
"Blogs, Twitter and other social technologies are helping to turn up the volume, but mostly people still get most of their news from mainstream sources," she said.
Editing by Frances Kerry and Eric Beech
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