On March 31, 2013, the Chinese health ministry quietly notified the World Heath Organization of three mysterious deaths. After developing coughing and sneezing symptoms, the victims’ lungs had filled with fluid, and they died gasping for air. The only thing they had in common was being around live chickens. One victim worked at a poultry market, and the other two recently had shopped at one.
Tests revealed what global health officials had feared for decades: There was a new form of avian influenza. “This strain usually caused mild symptoms like redness of the eyes or low-grade respiratory problems in humans,” said Daniel Jernigan, head of the influenza division of the U.S. Centers for Disease Control and Prevention. “ We knew it was different and much more severe when it killed three people.”
More than four years later, the virus has spread across southern China and sickened nearly 1,560 people, nearly 40 percent of whom have died. In May, the CDC ranked the influenza strain H7N9 the highest possible threat for viruses at risk of causing a worldwide pandemic ― just a year shy of the 100th anniversary of the Spanish flu outbreak that claimed nearly 50 million lives in 1918.
Although reports of new infections stopped in March, health officials are worried about the virus changing into a form that’s easily transmitted between humans. A new paper published this summer forecast the virus being three mutations away from such a reality.