(Courtesy Reuters/Jason Lee)
With seasonal warming, H7N9 disappeared, and health authorities around the world crossed their finders, hoping they’d seen the last of the virus. But H7N9 resurfaced in October, on the other side of China: Guangdong province and, from there, Hong Kong. As was the case ten months ago, authorities cannot find clear connections between infected birds and humans, there is some evidence of human-to-human transmission, and closure of live animal markets seems advisable. China’s neighbors are now getting nervous, and recently, the U.S. Centers for Disease Control and Prevention issued a level two travel advisory for China. (Shanghai health authorities announced that from January 31 to April 1, 2014, all its animal markets will be shut down. We were left to wonder why they are waiting until late January, given H7N9 is already in circulation; why the closure isn’t extending across a broader Chinese geography; and where people will find chickens, ducks, geese, and pigeons to eat. It is not common practice in China to sell poultry that is butchered, wrapped in cellophane, and sold from refrigerated supermarket cases, as is the case in the West. If Chinese people can manage to find poultry to eat during a live market shutdown, why not now make the transition to safer market sales of bird meat?)
Recent surveys find distribution of influenza across China is a mosaic of the older H5N1 virus, H7N9, and several other bird flus, creating real headaches for the country’s surveillance team. Finding flu in a bird doesn’t mean it’s the right flu. In October, researchers reported the H7N9 virus has an unusual dual capacity, genetically, to infect mammalian respiratory tract cells while retaining avian infection capacity. This week, researchers from the Mount Sinai School of Medicine in New York revealed that genetic studies of H7N9 show more disturbing facets of the virus. It is completely resistant to the primary anti-flu drug Tamiflu (oseltimivir) and its chemical kin, and partially resistant to the only other class of anti-influenza drugs. Despite having the capacity to withstand anti-viral treatment, H7N9 remains virulent and transmissible. One set of mutations imparting resistance has not forced a predicted diminution in other powers of the virus.
We will be watching H7N9 closely as winter unfolds in Asia.