BALTIMORE (WJZ)—Despite vaccines that prevent it, the number of whooping cough cases is up significantly across the nation.

Alex DeMetrick reports that includes an increase here in Maryland.

When a Baltimore County teacher at Harford Hills Elementary School came down with a possible case of whooping cough, she was not alone.

“Unfortunately we have been seeing an increase in the number reported to us,” Dr. Lucia Donatelli, Baltimore County Health Department.

In Baltimore County, 48 cases have been reported this year, and 294 in Maryland.

It’s part of a nationwide increase. Last year, there were more than 18,700 cases. So far this year, there have been more than 34,000.

“It’s transmitted through the air through respiratory droplets. So spray from a sneeze, spray from a cough, things like that,” Donatelli said.

But a series of early childhood vaccinations can prevent whooping cough.

A booster shot at age 5 means families at the school aren’t unduly alarmed about the teacher’s apparent case spreading to their vaccinated kids.

“I just read they are required to have a booster, so I’m not worried at all,” said Becky Kodzis, parent.

Besides young children, there’s another group that needs to be immunized against whooping cough.

“People that are around small children, particularly those kids that are under 1 year that are underimunized, because what we’re finding in our cases with small kids is that they’re getting it from the adults who take care of them,” Donatelli said.

Another booster shot later in life can keep that from happening.

While whooping cough can pose serious health risks to children under the age of 1 year, most cases can be treated with antibiotics.