The number of swine flu deaths outside Mexico has risen to four, according to the World Health Organisation.
Latest information from the WHO shows that three people have now died in the United States from H1N1 influenza A. One person in Costa Rica has also died.
In Mexico, where the outbreak began, there have been 56 deaths and 2,059 confirmed human cases.
So far, 30 countries have officially reported 5,251 cases. Scientists have warned that up to a third of the world’s population could become infected.