US President Barack Obama has been tested for swine flu after he just returned from a trip to Mexico where he was discussing the escalation of the country's violent drug related problems.

The president is assuring Americans the country is taking aggressive measures to control the virus.

New cases of swine flu have surfaced in the United States and Canada, taking the total to 26.

There are now more than 1300 suspected cases in Mexico.

People who are infected can spread the virus before they even start showing symptoms.

The symptoms of the H1N1 virus are similar to numerous other flu viruses - fever, headache, muscle aches, dry cough and extreme tiredness - and in this case also vomiting and diarrhoea

While most cases in the United States and Canada have been mild, it has killed up to 81 people in Mexico, including some fit young adults.

H1N1 has been around since the 1918 flu pandemic, in various forms but no one knows if this strain is different enough to cause widespread and severe disease.

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