There is a pertussis — whooping cough — outbreak in southern Alberta. There have been 34 cases in the Lethbridge and Medicine Hat areas, Alberta Health Services warned Tuesday.

There have been two cases in Calgary so far this year.

Dr. Judy MacDonald, the medical officer of health for Calgary, says children under six months of age are the most vulnerable.

"Pertussis is really quite serious especially in infants under six months of age when this particular bacteria can interfere with their ability to breathe it can cause pneumonia, seizures, encephalitis and it can really lead to death especially in those young children."

MacDonald says adults can get a booster shot at public health clinics if they think they need it.

Alberta Health Services is also recommending women in the south zone who are in their third trimester of pregnancy to get the pertussis vaccine.

It says it will help protect the babies in their first few months.