Alberta Health Services has sent a warning to parents of studnets at Foothills Composite High School about Whooping Cough, or Pertussis within the school.

From the start of 2017 until the first part of this week, AHS has had three cases of whooping cough in Okotoks reported to them.

They now have three lab confirmed cases, and an additional six reported that are linked to those.

Dr. Judy MacDonald, the Calgary Medical Officer of Health, says while the recent cases reported seem to be within families, there's still a risk for others.

"These are families that have not immunized their children, there is a potential that because these children have gone to school that they could have exposed others, we are obviously watching for more cases of Pertussis to occur."

Another name for Pertussis, is the 100 day cough, the first symptoms are similar to a cold, a runny nose, sneezing, mild fever and cough. The cough will progress from there, to severe coughing spells sometimes ending in vomiting.

After that the cough will gradually disappear over weeks to months, as Pertussis can persist for a very long time.

MacDonald stresses the need to stay up to date on Pertussis immunization, even as an adult, as the disease is preventable, and can be deadly to infants.

"I'd just like to emphasize the importance of immunization, infants under six months of age, if they get Pertussis, it can be so severe that it leads to hospitalization and death, because these babies just cant catch their breath."

Pertussis immunizations begin at two months of age, and doses continue at four, six and 18 months, a preschool dose, another in grade nine, and another is recommended for anyone over the age of 18.

If you have any symptoms of Pertussis contact your physician.