Measles sign

Medical health officers in Lethbridge say they are bracing for a larger measles outbreak. (Devin Heroux/CBC)

The number of measles cases in the Lethbridge area has now climbed to 18, provincial officials confirmed Monday.

Cases in the southern Alberta city have been steadily rising since the outbreak was first reported last month. 

Alberta Health Services officer Dr. Richard Musto expects the number to climb even higher.

"Where we have populations that are under-immunized, this virus is very, very infectious and spreads easily. So, I expect we may see some more cases. The fact that we're at 18 is not a great surprise."

Musto says additional immunization clinics are being offered in the south zone, which covers much of southern Alberta. Immunizations are not mandatory in the province, but he says teams on the ground have been working hard to limit the spread of the disease, adding that other Alberta Health Services zones are looking at what vaccinations they might need to do.

"It's an opportunity for us to review our own coverage rates for the measles vaccine and see if there are any populations that are particularly under-vaccinated. Of course, we're in preparation mode but, at the moment, there have been no reported cases outside of the south zone," said Musto.

The original case has been traced back to a traveller from the Lethbridge area who recently returned from Holland, site of a measles outbreak.