Mexico identifies 573 H1N1 cases

Health officials in Mexico have identified 573 cases of influenza A H1N1, which is up from 333 instances as of the previous week.

The swine flu strain represents 90 percent of the country's influenza cases, though authorities said that the near doubling of cases from week to week does not quality as a new health emergency. There have been nine deaths as a result of the outbreak, the Telegraph reports.

An outbreak of the same swine flu in Mexico and the United States in 2009 quickly became a global pandemic. There were 17,000 deaths worldwide from the pandemic and 1,250 in Mexico alone. The pandemic ended in 2010 and the World Health Organization said that flu patterns had returned to typical levels.

In early January, 12 American citizens were reported to be infected with influenza A H1N1 swine flu. There were fears that the virus had mutated to H3N2v, which is the strain transmitted more easily between humans.

"While there is no evidence that sustained human-to-human transmission is occurring, all influenza viruses have the capacity to change and it's possible that this virus may become widespread," the US Centers for Disease Control and Prevention, said, according to the Telegraph.

The influenza A H1N1 virus has been found in five states in the United States since August. Two cases have been reported in West Virginia, three in Pennsylvania, two in Maine, three in Iowa and two in Indiana, according to the CDC.