The Health Protection Agency annual conference at Warwick University, UK, heard that such websites could indicate an outbreak of flu earlier than conventional disease surveillance methods based on doctor visits.
Combing for messages or "tweets" such as 'I have flu' or 'I've got swine flu' may help provide valuable insight into the spread of infectious diseases, research showed.
Ed de Quincey, a computer scientist at City University London conducted the research and developed the system with his team at the City eHealth Research Centre.
"As UK public health agencies and the NHS are preparing for the approaching flu season amid the H1N1 pandemic, new forms of social interaction via web sites such as Twitter and Facebook can expand the sources used in monitoring such outbreaks," the Telegraph quoted him as saying.
"The flu pandemic was the perfect opportunity to test this idea and we found that at least 4,000 people reported flu symptoms via Twitter since May 2009.
"We are currently analysing over a million 'tweets' that we have collected and exploring the potential of incorporating data from other social networking websites. We hope in the future to expand this approach to investigate other health issues such as drug and substance abuse," he added.