12/13/2017 09:57 EST | Updated 12/15/2017 10:41 EST

Health officials declare whooping cough outbreak in southern Alberta over

LETHBRIDGE, Alta. — Health officials say an outbreak of whooping cough that began last spring in southern Alberta is over.

Alberta Health Services says cases of pertussis in the south zone have decreased so much that the situation can no longer be considered acute.

The health agency says the bacterial infection first surfaced June 5 and 441 cases were confirmed in the six months ending Dec. 7.

Of those, 388 were connected with the outbreak.

Health officials will continue to monitor and do followups.

AHS also continues to stress the importance of routine childhood immunizations — which are free in Alberta — to control the illness.

The affected area stretched from Fort Macleod to Coaldale and took in Lethbridge County and the city of Lethbridge.

Pertussis causes severe coughing that lasts for weeks. Any age group can be affected, although children under a year old are the most at risk for serious complications, which include convulsions, brain damage or even death.

At its height, the outbreak was spreading in schools, school buses, preschools and daycares. Those affected ranged in age from one to the mid-70s.

The region also had a whooping cough outbreak in 2009 which  lasted 10 months.