In a move that caught many public health experts by surprise, the World Health Organization quietly announced Thursday that it would stop tracking swine flu cases and deaths around the world.
The announcement, made in a “briefing note” posted on the organization’s Web site late in the day, perplexed some experts, and even baffled a W.H.O. spokesman, Gregory Hartl, who said in an e-mail message, “I don’t have reliable info” about what his agency would track instead.
Only a little earlier in the day, Mr. Hartl had confirmed that Argentina, with 137 swine flu deaths since June, had surpassed Mexico, where the epidemic began in February, as the country with second largest number of swine flu deaths. Mexico has 121, and the United States, with a much larger population, has 211.
The last W.H.O. update, issued on July 6, showed 94,512 confirmed cases in 122 countries, with 429 deaths.
Many epidemiologists have pointed out that, in reality, millions of people have had swine flu, usually in a mild form, so the numbers of laboratory-confirmed cases were actually meaningless. And performing the tests has overwhelmed many national laboratories.
The briefing note said countries would still be asked to report their first few confirmed cases. It also said countries should watch for clusters of fatalities, which could indicate that the virus had mutated to a more lethal form. Other “signals to be vigilant for,” it said, were spikes in school absenteeism and surges in hospital visits.