Washington, May 9 (Inditop) The number of human swine influenza cases in the US increased to 1,639 Friday, the Centres for Disease Control and Prevention (CDC) said, surpassing Mexico’s total for the first time.

As the figure nearly doubled overnight, the CDC said that most of the surge was attributable to increased testing capabilities as well as the continued transmission of the virus.

CDC acting director Richard Besser said while the virus was spreading across the country, the level of severity was similar to that of seasonal flu.

As of Friday, there were 1,639 confirmed cases in 42 states and the District of Columbia, and another 850 probable cases nationwide. The median age of those affected was 14 years, Besser said. A day earlier there were 896 confirmed cases.

At least 26 people were in hospital, but the CDC also noted that most of those sickened were recovering and their illness lasted less than a week and most were under 18 years.

Mexico, which has been the epicentre of the global outbreak, reported 1,204 confirmed cases and 42 deaths, according to the World Health Organization.

“I want to ensure everybody that we’re seeing that the virus may not have been as virulent as we at first feared, but we’re not out of the woods yet and we still have to take precautions,” President Barack Obama said at a White House townhall meeting conducted in Spanish.

“Our experience with the H1N1 virus over the last couple of weeks is a sobering reminder of how vital it is that we all recognize we’re all in this together … we can’t be divided by communities,” Obama said.