Alberta Health Services says that the number of confirmed cases of measles in Lethbridge has grown again.

There are now 13 confirmed cased of the disease in the community, but that number could grow as more test results on suspected cases come in.

Officials say that not all of the cases came from known cases and that’s concerning them because it makes it difficult to track where people are contracting the disease.

“There's two types of cases,” says Dr. Vivien Suttorp, Medical Officer of Health. “The first type is individuals who may have direct contact with a known case, and the second type is individuals who we cannot link to a known case. And it’s the latter that's more worrisome to public health and health care providers, because people are picking this up somewhere and we don't even know where that is.”

Measles is highly contagious and people exhibiting symptoms are urged to call Health Link before heading to the doctor’s office.

They’ve set up a portable isolation containment tent at the Chinook Regional Hospital to keep the sick patients from spreading the illness.

AHS is also planning to increase the number of immunization clinics in the coming days in an attempt to curb the outbreak.

They’re also looking at expanding clinics to the Bow Island and Medicine Hat area with a particular focus on children, including those between six and 12 months of age.

Measles attacks the respiratory system can lead to serious complications such as pneumonia, otitis media, acute encephalitis, and corneal ulceration.

The complications are usually more severe in adults.