An archeologist, Felipe Solis, who shook Barack Obama's hand in Mexico died the next day from symptoms similar to those of swine flu.
The White House insisted the President's health was not in any danger, but he was said to be taking the threat of an epidemic 'very seriously'.
The President's health advisers were already concerned about his visit south of the border after learning the contagious virus first struck in Mexico City on April 13 - three days prior to Mr Obama flying in to meet Mexican government officials.
Health fears: American President Barack Obama shook hands with Felipe Solis, who died the following day from flu-like symptoms. Mexican health authority, Jose Cordova, however, said Mr Solis was already ill and his death was unrelated to swine flu.
White House spokesman Robert Gibbs insisted: ‘The president’s trip to Mexico has not put his health in any danger.’
He added: ‘The incubation period is 24 to 48 hours and we have been back from Mexico for nine days now. The doctors say he was not at risk.’