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Posted by Dr. Sushrut Jangi May 28, 2013 11:49 AM
Occasionally, I'll be presenting stories about medicine from around the world. We'll travel to different settings to unravel and explore novel and emerging diseases, newfangled treatments, and little mysteries that shed light on human health, asking local doctors and researchers here in Boston to contribute their expertise. As our world grows more connected, events that affect human health in any country have the potential to involve all of us.
May 28, 2013
You've probably heard about the new bird flu, called H7N9, that has been simmering in Eastern China and has already killed 36 people. Given that Beijing is the second busiest airport in the world, a reasonable fear is that a Chinese flu epidemic could quickly spread if an infected person travels out of the country. Could this flu come to the US and turn into a global pandemic?
It could - but only if the virus spreads easily between people.
Sometime in early February of this year, a middle-aged man living in Shanghai City visited a live bird market. He picked out a seemingly healthy chicken which the vendor slaughtered on site. He brought the freshly killed animal home, where he washed, prepared, and cooked it.
Within 2 weeks of eating this meal, the man's body temperature shot up to 106 degrees Farenheit and he developed chills and was coughing up mucus. By February 20th, he was admitted to a local hospital, where his lungs failed. A week later, the man died in the hospital from this sudden illness.
But here's what's potentially alarming. The man from Shanghai hadn't lived alone. His father and brother stayed in the same house. In mid-February, both of these men developed coughs and high fevers. A week later, the man's father was also dead. The brother, luckily, improved. Both men were found to be infected by a bird virus that we now call H7N9.
Since all three men lived in the same house - can we assume the virus can pass between people? "The investigation by an international scientific team concluded that the evidence so far is not sufficient to say that person-to-person transmission has occurred," says Marc Lipsitch, Director of the Center for Communicable Disease Dynamics at the Harvard School of Public Health.
In short - no - we can't assume they caught it from each other. Instead, the three men may have picked it up from a visit to the local poultry market. Buying fresh poultry from a market is not unusual in China, where stacks of cages sprawl several blocks and contain birds, ducks, quail, and other animals in close quarters, providing ample opportunity for viruses to intermingle and generate new strains, in a process called reassortment. Humans probably pick up these new viruses after exposure to these birds, a risk that greatly increases during the process of slaughtering, preparing, and cooking (but not eating) a chicken.
Consequently, the Chinese government has chased after the suspected exposure by shutting down poultry markets. The results, so far, are decent. The epidemic has begun to wane - the last known case was reported on May 8th. So thus far, humans don't appear to be spreading the infection to each other at detectable rates. Even if an infected person boards a plane bound for the US, he is unlikely to pass the disease to his fellow passengers.
But neither the US nor the Chinese CDC has put its guard down. There are alternative ways the virus can leave China other than inside people on planes. Since birds infected with H7N9 don't get sick the way humans do, they can silently spread the disease between countries. Some poultry from China are transported into nearby Vietnam. And the virus may be quietly transported by other winged birds that can fly vast distances outside of China.
And what of the three men who lived in the same house that all fell sick? Even if they visited a bird market, isn't it also a possibility they did really catch it from each other?
It certainly is.
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