There have been no reported cases of the new H7N9 avian flu in the U.S., officials at the U.S. Centers for Disease Control said Friday. In China, however, the numbers of victims continue to creep up, with 16 people in four provinces having been sickened with the virus.
Six of those people have died, said CDC director Dr. Thomas Frieden during a phone call with reporters.
Health authorities in the two countries do not believe that the flu strain is transmissible between humans. "There is no evidence that this is spreading from person to person," Frieden said. With a typical flu that passes easily between people, 20% to 30% of family members of victims get sick, he added. So far, Chinese authorities have monitored more than 100 associates of the H7N9 victims, and none have been shown to have fallen ill.
Investigators are still studying two families where members were sick with respiratory problems at the same time as a relative had H7N9 to make sure there was not person-to-person transmission in those situations. But even if there was, Frieden said, that does not mean H7N9 will spread quickly in the general population.
The H7N9 illnesses in China all struck between Feb. 19 and March 31. Fifteen of the victims were adults ages 27 to 87; one was a 4-year-old child, who had a mild case. Most had some direct contact with live poultry in markets.