"The scare has spawned a spamming frenzy, like sharks smelling blood in the water," Symantec's Mayur Kulkarni wrote in a THIS IS blog post.

Security firm F-Secure has compiled a list of 146 swine flu-related internet sites that have been registered over the last few days by scammers looking to collect "donations" and peddle malware, fake pills and bogus swine flu survival guides.

McAfee said domain name registrations mentioning the word "swine" were up by about 30 times. One of the new sites, noswineflu.com, offers a dodgy "Swine Flu Prevention Guide" for $US19.95.

McAfee and Symantec also revealed a surge in spam campaigns riding on the back of the flu threat, which instead of delivering useful information distribute viruses and offer bogus pills that purportedly eradicate the flu.

When victims go to buy any products offered by the spammers, their credit card details are harvested.

Victims may also be sent bogus drugs purporting to be generic versions of the antiviral drug Tamiflu, which could pose health risks, Sophos warned.

The same fake pharmaceuticals were being peddled by scammers during the bird flu scare.

Subject lines from the spam emails include "Madonna caught swine flu!" and "Swine flu in Hollywood!". The messages contain links either to online pharmacy sites selling counterfeit drugs or malicious sites that infect target computers with password-stealing viruses.

Cisco IronPort estimated that swine flu-related messages already account for up to 4 per cent of the world's spam.

The US Government-run Computer Emergency Readiness Team, US-CERT, acknowledged the email scams and warned people not to open any malicious links or attachments.

"If users click on this link or open the attachment, they may be directed to a phishing website or exposed to malicious code," US-CERT warned, adding that all official information can be found on the website of the US Centres for Disease Control and Prevention.

The World Health Organisation today raised its flu alert signalling a swine flu pandemic is "imminent" after a toddler in the United States became the first to die of the disease outside of Mexico.

About 100 people are being tested for the virus in Australia, with no update on their conditions available yet today.

Twitter 'creating hysteria'

Aiding the swine flu scammers is the persistent rumours and fear-mongering that is spreading across social networking sites such as Twitter, on which swine flu has been one of the hottest topics this week.

In a column for Foreign Policy magazine, Evgeny Morozov argued that, rather than helping people stay informed, Twitter was creating hysteria and misinformation.

He argued that gossip and speculation - such as warnings to stop eating pork - were drowning out information from official sources, such as the official Twitter feed

for the Centres for Disease Control and Prevention.

"In the context of a global pandemic - where media networks are doing their best to spice up an already serious threat - having millions of people wrap up all their fears into 140 characters and blurt them out in the public might have some dangerous consequences, networked panic being one of them," Morozov wrote.

Conversely, a US biosurveillance start-up, Veratect, claims monitoring online social network and blog chatter helped it alert the CDC to the situation in Mexico on April 16, before Mexican health authorities acknowledged the swine flu threat.

Veratect chief executive Bob Hart told Wired.com: "We started picking up the early indicators of social disruption, whether it shows up on blogs or Twitter. We can pick up the first indicators of behavioral changes."