As of the World Health Organization reports Friday, there are 11 countries and 331 cases were confirmed to have been infected with the influenza A (H1N1).

The virus commonly known as swine flu has spread rapidly, the hardest-hit areas were in the Western hemisphere, the organization said.

The largest outbreak of the virus was in Mexico, which had 156 confirmed cases including 9 deaths, according to the WHO. While Mexican Health Minister Jose Angel Cordova Villalobos said Thursday that the country has more than 300 confirmed cases of the virus and the death toll had risen to 12, a higher number than the WHO reported Friday.

In the United States, the Centers for Disease Control and Prevention said Friday it had confirmed 141 cases of the flu in 19 states and one person had died.

A senior WHO official said Thursday that the higher totals did not necessarily mean the incidence of the disease is increasing. Dr. Keiji Fukuda, assistant director-general of WHO, said it could be more to do with health investigators getting through their backlog of specimens.

In addition to Mexico and the United States, WHO said, the following countries have confirmed non-death cases: Austria (1), Canada (34), Germany (3), Israel (2), Netherlands (1), New Zealand (3), Spain (13), Switzerland (1) and the United Kingdom (8).

In addition, 230 cases are being investigated in the United Kingdom, and Spain has 84 suspected cases and Australian 114 cases were under investigation.

WHO also advises people who are ill better to delay international travel and for people who are developing symptoms following international travel to seek medical attention in line with guidance from national authorities.

There is also no risk of infection from this virus from consumption of well-cooked pork and pork products. the WTO said in a statement. Individuals are advised to wash hands thoroughly with soap and water on a regular basis and should seek medical attention if they develop any symptoms of influenza-like illness.”