April 27 Governments around the world took action on Monday to try to prevent a possible flu pandemic as a virus that has killed up to 149 people in Mexico spread elsewhere.
The World Health Organization decided at the weekend to activate its 24-hour "war room" command center .
The World Health Organization says 149 people died of flu-like symptoms in Mexico, though not all of them are yet confirmed to have been infected with the new virus.
Here are details of the latest number of cases and some facts about previous influenza outbreaks:
COUNTRY DEATHS CASES SUSPECTED CASES
MEXICO Up to 149 26 1,600
U.S. 0 40 0
CANADA 0 6 0
BRITAIN 0 2 1
SPAIN 0 1 20
NEW ZEALAND 0 0 14
SWEDEN 0 0 5
GERMANY 0 0 3
ISRAEL 0 0 2
FRANCE 0 0 4
NORWAY 0 0 1
* Seasonal flu kills between 250,000 and 500,000 people globally in an average year. Here are some details of previous pandemics:
-- Three worldwide (pandemic) outbreaks of influenza occurred in the 20th century, in 1918, 1957 and 1968. It is estimated that approximately 20 to 40 percent of the worldwide population became ill and more than 50 million people died in the earliest of the outbreaks. The most recent, between September 1968 and March 1969, killed 33,800 people.
-- The three have been informally identified as Spanish, Asian, and Hong Kong influenza, respectively. They are now known to represent three different antigenic subtypes of influenza A virus: H1N1, H2N2, and H3N2, respectively.
Sources: Reuters/WHO/CDC (Writing by David Cutler, London Editorial Reference Unit; Editing by David Storey)