The World Health Organization said Friday that 2,837 people have been reported as swine flu fatalities, as H1N1 ebbs and flows in various parts of the world.

The death toll is up at least 625 in the last week, from 2,185 published in last week's update from the UN health agency.

"There is no sense that the virus has mutated or changed in any sense," WHO spokesman Gregory Hartl told a news briefing in Geneva. "We are continuing to see increased number of deaths because we are seeing many, many more cases."

Hartl attributed the increase in the number of deaths to an overall rise in the number of people who have become infected with the H1N1 virus.

The number of laboratory-confirmed cases has reached 254,206, though the figure understates the actual number since countries are no longer required to report individual cases.

Flu activity worldwide

Countries such as India, Bangladesh, Myanmar, Cambodia, Sri Lanka, and Indonesia are reporting "increasing or sustained high levels of respiratory disease," and a few (Thailand and Brunei Darussalam) have begun to report a declining trend, the WHO's latest update said.

Countries in the equatorial and tropical regions of South America, such as Ecuador, Venezuela, Peru, and parts of Brazil, continue to experience regional or widespread influenza activity, with many reporting an increasing trend in the level of respiratory diseases.

Widespread geographic activity is also reported in Central America and the Caribbean including Costa Rica, El Salvador, Guatemala, Honduras, Panama, and Cuba, but most of these countries are now reporting a declining trend, WHO said.

In the Northern Hemisphere, Japan continues to experience an early start to its annual flu season. Influenza activity remains "low overall" in Canada and the U.S., although a regional increase has been detected in the southeastern United States.

More cases are being seen in the U.S. as schools and colleges resume, Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, said Thursday.