In Indonesia the disease is spreading so rapidly, particularly in the capital of Jakarta, some health officials strongly suspect the long-dreaded mutation has already occurred.
"There are just too many people who have it," said one doctor. "In many cases, it is difficult to establish any contact with birds."
Another official said the flu has "spread all over the city."
Dr. Charoen Chuchottaworn, an avian-flu expert at the Thai Public Health Ministry, said doctors reviewing cases were alerted by the very mild symptoms present in both patients, neither of whom had had any recent contact with birds or poultry, may be the beginning of the much feared human-to-human transmission.