Speaking at the Chinese Center for Disease Controls, Premier Li Keqiang praised authorities for their efforts in tackling H7N9 so far, but warned that they should be prepared for the virus to mutate into a form that could transmit between humans.
Over 100 people have now fallen ill with the virus and 23 people have died. The majority of cases have been reported in the east of the country, although the most recent cases include a woman in the southern province of Hunan and a man in Taiwan, the first case to be reported outside mainland China.
Establishing a source
Authorities continue in their efforts to establish the source of the virus. China’s Ministry of Agriculture (MOA) reported on Friday (26 April) that it had collected a total of 390,628 samples at surveillance sites across the country, including live poultry markets, poultry slaughterhouses, poultry farms, wild bird habitats, pig slaughterhouses and pig farms.
So far, 218,897 samples have been tested, including 150,837 serology samples and 68,060 pathology samples, with 0.07% of the pathology samples testing positive for H7N9. The majority of positive samples were collected from live poultry markets in east and central China, although samples from wild and domestic pigeons also tested positive for the virus.
None of the samples taken from poultry and pig farms tested positive, the MOA said.
Meanwhile, a study by the University of Hong Kong (HKU) and Zhejiang University, published in scientific journal The Lancet, concluded that China’s wet poultry markets were the most probable source of the outbreak.
The study found that the strain of virus contracted by four patients in Zhejiang was almost identical to the strain found among chickens at a poultry market in the region.
Researchers also discovered that the patient virus contained a mutation that was important for adaption to a mammalian host, although they confirmed that no human-to-human transmission had been identified among the contacts of the four patients.
Two of the four patients studied died from the virus and researchers revealed that these cases exhibited “cytokine storms”, a dangerous immune reaction, which has also been observed in cases of H5N1 bird flu and SARS.
A team of experts in veterinary epidemiology, emerging avian diseases and disease control policy from China’s MOA and the World Organisation for Animal Health (OIE) is currently conducting a week-long inspection tour of areas in China where H7N9 has been identified, including Shanghai and Zhejiang.