W.H.O. Says It Is Closer to Declaring Flu Pandemic

The disease has reached 64 countries, and there have been dozens or hundreds of cases in several nations outside North America, including Britain, Spain, Japan, Chile and Australia.

The Southern Hemisphere countries are now of chief interest because their winter flu season is just beginning and another strain of the H1N1 virus, widespread last winter, was resistant to the antiviral drug Tamiflu.

To raise the flu alert to its highest level, Level 6, the W.H.O. would need to find evidence of widespread “community transmission” — meaning beyond travelers, schools and immediate contacts — on two continents.

No cases have been reported anywhere in Africa. Historically, there has been little flu surveillance on the continent, which has many more serious diseases to track, though South Africa has a laboratory that regularly reports cases to the W.H.O.