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MONDAY, June 24 (HealthDay News) -- Chinese health officials say health care workers should prepare for the possible re-emergence later this year of the deadly H7N9 bird flu, which has killed one-third of patients hospitalized with the virus.
"The warm season has now begun in China, and only one new laboratory-confirmed case of H7N9 in human beings has been identified since May 8, 2013," said researchers from the Chinese Center for Disease Control and Prevention and the University of Hong Kong. "If H7N9 follows a similar pattern to H5N1, the epidemic could reappear in the autumn." H5N1 is another bird virus that appeared in 2003.
"This potential lull should be an opportunity for discussion of definitive preventive public health measures, optimization of clinical management and capacity building in the region in view of the possibility that H7N9 could spread beyond China's borders," the researchers reported June 23 in the journal The Lancet.
Their research suggests that H7N9 has a lower death rate than H5N1, which killed about 60 percent of patients admitted to the hospital, but is deadlier than the 2009 H1N1 swine flu virus that killed 21 percent of patients admitted to the hospital, according to a second report by the same team in The Lancet.
The researchers also calculated that between 0.16 percent and 2.8 percent of all people who are infected with H7N9 and develop symptoms are at risk of dying. The wide variation in the estimate is due to the difficulty of accurately measuring how many people are infected with H7N9 but experience only mild symptoms.
"Assessing the severity profile of human infections is vitally important in the management and treatment of any infectious disease outbreak," the researchers wrote in a Hong Kong University news release. "Although previous clinical case series have focused on the potential for avian influenza H7N9 virus infection to cause severe illness, we have estimated that mild cases might have occurred."
Many of the people who contracted H7N9 had contact with poultry. No cases of H7N9 outside of China have been reported thus far.
The researchers said their results suggest a need for continued vigilance and sustained intensive control efforts against the virus to minimize the risk of human infection, which is greater than previously recognized.
The U.S. Centers for Disease Control and Prevention has more about H7N9 bird flu.