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 the second-largest number of swine flu deaths. Mexico has 121; the United States, with a much larger population, has 211.
The last W.H.O. update, issued 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 mild form, so the numbers of laboratory-confirmed cases were actually meaningless. And performing the tests has overwhelmed many national laboratories.
But the cases — and, more to the point, the deaths — have been closely watched by the media and flu experts, even those who knew they were undercounts, as a crude measure of how the epidemic spread around the globe. Such figures can also, in theory, be useful to public health officials. For example, knowing that Chile has had far fewer deaths than Argentina even though their outbreaks began almost simultaneously could be useful to other countries who might want to imitate Chile’s response.
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 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.
Wealthy countries routinely collect such data, and also do blood tests to see what percentage of a population has flu antibodies, indicating they were infected but recovered. However, poor countries do not.
Dr. Joseph S. Bresee, chief of epidemiology for the C.D.C.’s flu division, said he agreed with the W.H.O. premise that case counts were just too inaccurate to keep using.
“I don’t know exactly what their plans are,” he said, adding that he hoped they would track the severity and spread of flu cases over time, as his agency does state-by-state in flu season. “But it’s not like they’re just going to let the screen go blank.”
Dr. Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said confused journalists in many countries had misread the low W.H.O. numbers of confirmed deaths to report that the new flu is not a threat. And testing is so hit-or-miss that even apparent differences in death rates like those between Chile and Argentina “may not be based in science,” he said.
“Bad measures can be worse than no measures at all,” he added. “But I hope this will force the public health community to come up with better ones.”
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