The United States experienced an unusually high outbreak of whooping cough in 2012–the largest in 50 years. The Centers for Disease Control and Prevention tallied 41,880 cases in a preliminary count, including 18 deaths. Now, health officials are looking into whether a new strain of the bacteria is responsible for the rise in infections.
Researchers have discovered cases of the illness caused by a germ that may stand up to the whooping cough vaccine. The new bug showed up in France, Japan and Finland. While experts say the new strain is not more deadly, Time reports, it may resist existing shots against it. A new study that is yet to be published shows the whooping cough vaccine lowers the risk of severe disease from the new strain in infants, but did not prevent the illness completely, the magazine reports. The new strain accounts for 14% of whooping cough cases in France.
“It’s quite intriguing,” Tom Clark of the CDC told Time. “It’s the first time we’ve seen it here.” Clark noted that the CDC needed more information before it could draw conclusions.
Whooping cough is an infectious bacterial disease that causes uncontrollable coughing.
A new strain of whooping cough alone, however, may not be responsible for the rise in cases in 2012. Last year, researchers learned that an old whooping cough vaccine–one administered before 1997–worked better than a new version. The U.S. began using an acellular pertussis vaccine instead of a whole cell pertussis vaccine in the late 1990s. But children who received the older vaccine were less likely to contract whooping cough before the age of 12 than those who got the new jab.